Main

The deadly coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), created an emergency situation in which mRNA vaccines were trialed in large cohorts of healthy donors (HDs), leading to the eventual approval of these vaccines by the Food and Drug Administration1,2. The delivery of monovalent mRNA vaccines and subsequent boosters according to a three-dose injection schedule resulted in an effective reduction of severe COVID-19 infections and deaths3, with effectual protection against the ancestral virus and its variants of concern. To date, in response to the emergence of highly contagious and immune-evasive variants, updated reformulations of mRNA vaccines, such as the Wuhan-Hu-1 (WA.1)/Omicron BA.4/5 bivalent or XBB.1.5 monovalent formulations, have been introduced. The efficacy of mRNA vaccines has been assessed by investigating both humoral and cellular responses in the healthy population, where they induce prolonged germinal center (GC) activity4,5, the generation of high-affinity neutralizing antibodies (nAbs) and the establishment of immune memory6,7, as well as de novo B cell engagement upon booster vaccination8,9. While GC activity can be detected at least up to 6 months after vaccination, the rapid waning of circulating antibodies and nAbs10 suggests that the formation of long-lived plasma cells might be limited11. Correlates of protection against reinfections and/or severe disease have been proposed to include anti-receptor-binding domain (RBD) titers and antiviral nAbs, as well as persisting memory B and T cells12.

Despite the demonstrated safety and efficacy of SARS-CoV-2 mRNA vaccines in immunocompetent individuals1,2,13, a full understanding of their effectiveness in immunocompromised persons is still lacking. Overall, previous studies have demonstrated that immunomodulatory drugs can result in poor vaccination responses14 and a higher risk and severity of bacterial and viral infections15. Yet, there is still a paucity of information about the mechanisms controlling mRNA vaccines’ immunogenicity and long-term efficacy in immunocompromised and autoimmune patients diagnosed with systemic lupus erythematosus (SLE).

Previous studies reported reduced immunogenicity of COVID-19 vaccines in a wide spectrum of autoimmune disorders16, including SLE17. Largely, those studies addressed mRNA vaccine efficacy in patients with lupus by assessing the seroconversion rate of anti-spike immunoglobulin G (IgG) responses in small-sized cohorts17,18. To date, the cellular basis of these antibody deficiencies and the impact of anti-B cell therapies other than rituximab-induced B cell depletion have not been addressed.

In this study, we investigated the efficacy of SARS-CoV-2 mRNA vaccinations in patients with SLE, a B cell-induced disease19 with an important cross-talk with functionally abnormal T cells20,21. Several groups including our own have shown that B cell regulation is profoundly disturbed in SLE, with SLE heterogeneity underpinned by the expression of separate B cell endotypes22,23. Specifically, we have shown that the expansion of activated effector B cells and plasma cells segregates with more severe disease and may reflect a naive-derived extrafollicular endotype that is distinct from a GC/memory endotype and is predominant in Black patients with SLE. Notably, severe COVID-19 infections share these characteristics and induce prominent extrafollicular B cell differentiation and expansion of autoreactive antibody-secreting cells (ASCs)24,25.

Here, we show that patients with SLE have reduced antibody titers and IgG neutralizing activity and lack coordinated activity between the memory T and B cell compartments, with poor vaccine immunogenicity associated with increased extrafollicular immune endotypes and treatment with belimumab26,27, an anti-BAFF monoclonal antibody approved by the Food and Drug Administration for lupus therapy.

Results

Donor cohort characteristics and study design

To study the efficacy of mRNA COVID-19 vaccines in SLE, we enrolled donors who received two (Vax1 + Vax2) or three (Vax3) doses of monovalent (WA.1) BioNTech/Pfizer or mRNA-1273 (Moderna/National Institute of Allergy and Infectious Diseases (NIAID)) vaccines. The cohort consisted of patients with SLE (n = 79 patients; n = 10 prepandemic individuals, n = 69 vaccinees) and age- and sex-matched HD controls (n = 64 HDs; n = 8 prepandemic individuals, n = 56 vaccinees) collected between March 2021 and October 2022. The SLE group was enriched for female patients of Black ancestry, reflecting the race and sex bias of SLE and the demographics of the Atlanta metropolitan area (Supplementary Table 1). Owing to the restrictions imposed by the pandemic isolation requirements, the HD group had an underrepresentation of Black individuals relative to the SLE cohort. Samples were mainly cross-sectional collections, with longitudinal follow-ups as indicated in the diagrams (Supplementary Table 1 and Extended Data Fig. 1). Given that our study was designed to evaluate primary responses to mRNA vaccines, in the absence of any infection at a time when vaccine administration was erratic, longitudinal follow-up was limited to the fraction of patients who fulfilled these criteria. A total of 256 HD and 212 SLE samples were serologically evaluated for vaccine-induced antibody responses, and a total of 161 HD and 182 SLE paired peripheral blood mononuclear cell (PBMC) samples were assessed for antigen-specific B and T cell responses using high-dimensional flow cytometry combining antigen reactivity and deep immune profiling (Extended Data Fig. 2).

Lower seroconversion upon primary mRNA vaccination in patients with SLE

To assess the level of seroconversion in our two cohorts and to define the specificity, kinetics and persistence of circulating antibodies recognizing different portions of the mRNA-coded proteins, we performed an isotype-specific plasma screen28 against the following SARS-CoV-2 targets: S1 and S2 subunit domains of the spike protein, RBD of the S1 subunit, and the N-terminal domain (NTD) (Extended Data Fig. 3a). Nucleocapsid-specific IgG antibodies were also tested to exclude prior infections (Extended Data Fig. 3b). Overall, IgM responses were minor contributors to the spike reactivity in the HD cohort and were increased in the SLE cohort (Extended Data Fig. 3c). IgA-specific responses were largely induced against the spike domain and RBD (Extended Data Fig. 3d), with similar responses between the two groups. As previously reported, we observed a predominant IgG-mediated anti-spike and anti-RBD response (Extended Data Fig. 3e and Fig. 1a–g). Upon the administration of one vaccine dose (Vax1, 3–4 weeks), ~85% of HDs seroconverted, whereas patients with SLE had a lower seroconversion rate of ~58%, with significantly more negative/low responders (Fig. 1e and Extended Data Fig. 3e). Completion of the primary series of vaccines (Vax2) increased the seroconversion rate of both the SLE (88%) and HD (100%) groups, although reduced mean titers and overall increased number of negative/low responders remained among the vaccinees with SLE (Fig. 1f and Extended Data Fig. 3e). A booster dose (Vax3) normalized the mean titers of IgG RBD between the two cohorts (Fig. 1g).

Fig. 1: Serological evaluation of anti-spike vaccine-mediated antibody responses.
figure 1

ad, Luminex-based detection of RBD IgG-binding serum antibodies (net MFI values) in the HD and SLE cohorts, shown for each vaccine administration. Each dot represents a sample. Connecting lines show longitudinal collections. Comparisons between mRNA vaccines (BioNTech/Pfizer (aqua) and Moderna/NIAID (salmon)) are shown for Vax1 + Vax2 in the HD (a) and SLE (c) cohorts and for Vax3 in the HD (b) and SLE (d) cohorts. eg, Clusters of IgG RBD titers based on binned time points for samples collected at Vax1 (e), Vax2 (f) and Vax3 (g). Statistical analysis was performed with a two-sided Mann–Whitney U test and indicated when significant. Pie charts show the distribution of seronegative (MFI 0–2,500) and seropositive (low MFI 2,500–10,000, medium MFI 10,000–100,000 and high MFI >100,000) values. The number of samples is indicated in the pies, and the percentage of responders was compared using a chi-square test. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. MFI, mean fluorescence intensity; GMT, geometric mean titer; Pre-CoV, before the coronavirus pandemic; d, day(s); mo, month(s).

While the RBD of the S1 subunit has been described as a main target of broad nAbs, other non-RBD structural proteins of the spike, namely S2 and NTD, can harbor neutralizing epitopes. The S2 domain, harboring more conserved epitopes and some level of cross-reactivity with other coronaviruses, was targeted by IgG similarly in HD and SLE samples (Extended Data Fig. 3e), whereas the IgG reactivity toward the NTD was lower in the SLE cohort, potentially compromising the control of viral escape29 (Extended Data Fig. 3e). Preexisting immunity to the four seasonal common-cold coronaviruses (CCCs)—alpha coronavirus strains ‘HKU1’ and ‘229E’ and beta coronavirus strains ‘OC43’ and ‘NL63’—was similar at baseline, with the only detectable difference being the higher anti-OC43 IgG titers in SLE (Extended Data Fig. 3f). Whether this observation could be explained by either more frequent or prolonged seasonal infections in patients with SLE remains to be elucidated. Overall, the evaluation of serological responses to mRNA vaccination revealed a defective primary response in SLE that requires vaccine boosters for full seroconversion.

Reduced RBD-specific antibody competitiveness and neutralization in SLE

The functional activity of circulating RBD-specific antibodies was determined by a competitive ELISA to assess their efficiency in blocking the interaction of recombinant human RBD with its receptor, recombinant human angiotensin-converting enzyme 2 (ACE2) (Fig. 2a,b)30. Interestingly, while the overall anti-RBD titers were only mildly reduced in patients with SLE (Fig. 1), this group displayed significantly impaired ability to block ACE2 binding across most time points (Fig. 2a,b). Despite medium/high RBD IgG titers, SLE samples were more frequently enriched for either non- or low-competitive antibodies (Fig. 2c), which are usually low-avidity IgG antibodies30,31. To test the hypothesis that impaired ACE2-blocking activity could result from defective affinity maturation of B cell responses in SLE, we tested antibody avidity using surface plasmon resonance (SPR)32. Comparisons of off-rate values confirmed that patients with SLE were enriched for anti-RBD immunoglobulins with medium/low avidity, with the greatest impairment observed after Vax2; this was only partially rescued after the booster dose (Fig. 2d). Of note, at Vax2, the absence of detectable RBD binding (Fig. 2d, nonbinder) was detected exclusively in a fraction of patients with SLE treated with belimumab.

Fig. 2: Reduced neutralization and breadth in the cohort of vaccinated patients with SLE.
figure 2

a, ELISA determination of antibody-mediated inhibition of SARS-CoV-2 RBD binding to solid-phase ACE2. The graph shows the reciprocal plasma or serum dilution that blocks 80% binding (BD80) of RBD to human ACE2. log(BD80) values are shown as negative (0–1), low (1–2) and high (>2). Box plots represent the minimum to maximum values, showing all points as individual serum samples: HD (day 0, n = 5; 1 week pre-2nd, n = 14; Vax2 1–3 months, n = 19; Vax2 4 months–before Vax3, n = 23; Vax3, n = 48) and SLE (day 0, n = 8; 1 week pre-2nd, n = 16; Vax2 1–3 months, n = 47; Vax2 4 months–before Vax3, n = 59; Vax3, n = 51) Statistical analysis was performed using a two-sided Mann–Whitney U test. b, Pie graphs showing the frequency and statistical comparison of competitive immunoglobulins in the two cohorts. A chi-square with Fisher’s test was used for comparisons. The number in the circles indicates the total number of samples tested, whereas the numbers in the pies show the relative percentages of the negative (black), low (gray) and high (white) values. c, Graphs showing the linear correlation between the blocking of RBD binding to ACE2 (BD80) and the total RBD immunoglobulin-binding antibodies in the same sample, tested from vaccinated individuals from both the HD (left graph) and SLE (right graph) cohorts. d, Polyclonal antibody avidity (as measured by the dissociation off-rate per second) to the SARS-CoV-2 RBD protein at ~2–5 months after the second vaccination (Vax2) or ~3–5 months after the third mRNA vaccination (Vax3) for serum samples analyzed by SPR. Off-rate constants were determined from two independent SPR runs. The table shows the frequency of responders for each cohort and time point analyzed. An unpaired t test was applied. eg, Pseudoviral neutralization in vitro assay performed on plasma samples isolated from vaccinated individuals after Vax2 and Vax3. The graphs show the neutralizing titers inhibiting 50% of the viral growth (NT50) tested for the SARS-CoV-2 WA.1 wild-type (e), Delta (B.1.617.2) (f) and Omicron (B.1.1.529 BA.1) (g) strains. Each dot in the box plots represents an individual sample tested. Horizontal lines indicate the median. The pie charts show the comparison of negative, low and high neutralizers. Statistical comparison was performed using a chi-square with Fisher’s test. The number in the circles indicates the total number of individual samples tested, whereas the numbers in the pies show the relative percentages of the negative (black), low (gray) and high (white) values. Not significant, P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. HRP, horseradish peroxidase; amIgG, anti-mouse IgG; mFc, monomeric Fc; rec-hRBD, recombinant human RBD; rec-hACE2, recombinant human ACE2; d0, day 0; wk, week(s); pre-2nd/3rd, before the second or third dose.

To corroborate the ELISA results further, we performed pseudoviral neutralization assays33 against the SARS-CoV-2 WA.1 (wild-type), Delta (B.1.617.2) and Omicron (B.1.1.529 BA.1) strains (Extended Data Fig. 4a,b). Patients with SLE displayed impaired neutralization activity against those viruses, with significantly lower neutralization titers and reduced breadth, relative to their HD counterparts (Fig. 2e–g and Extended Data Fig. 4b). Interestingly, neutralizing titers decayed significantly faster in HDs relative to patients with SLE, with significant differences for the WA.1 wild-type (half-life of 38 days for the HD group versus 73 days for the SLE group; P = 0.03) and Delta (half-life of 39 versus 68 days; P = 0.03) strains after Vax3 (day 42 after vaccination and onwards)34. These data identify qualitatively defective and lower-avidity circulating antibodies resulting in reduced breadth of neutralization in patients with SLE.

Defective and distinct anti-spike B cell responses in SLE

To evaluate the magnitude of cellular responses and the identity of B cells induced upon mRNA vaccination, we performed immunophenotypic profiling with a high-dimensional 28-color flow panel that provided tetramer-based detection of WA.1 spike- and RBD-reactive B cells (Extended Data Fig. 2a and Fig. 3a,b). During the post-Vax1 priming phase, 62% of the HDs mounted an early anti-spike B cell response (Fig. 3c), with ~35% of anti-Spike B cells also binding to the RBD tetramer (Fig. 3d). Overall, the HD group displayed a higher and persistent anti-spike and anti-RBD recall response to Vax2 and Vax3 (Fig. 3c,d). The SLE group had a significantly lower proportion of responders after priming and within memory recall responses, with ~10–30% of patients failing to generate a detectable B cell response at any time (Fig. 3c,d). B cell lymphopenia is common in SLE owing to both disease activity and therapy. To account for this variable, we compared the frequencies of the total CD19+ B cells between the HD and SLE groups (Extended Data Fig. 4c). Both total and antigen-specific circulating B cells were reduced in patients with SLE, with enrichment of patients with very low B cell frequency (<1%) and low spike-reactive B cells (<0.0022%) (Extended Data Fig. 4c,d). Normalization of antigen-specific reactivity to B cell numbers confirmed that the SLE cohort carried more negative responders than the HD cohort (Extended Data Fig. 4e,f). Preexisting immunity to CCCs in the B cell memory compartment did not significantly influence the anti-SARS-CoV-2 B cell response, as measured by the level of cross-reactive WA.1+/CCC+ spike B cells (Extended Data Fig. 5a–c). Furthermore, this response was not notably different between the two cohorts (Extended Data Fig. 5c). Contrary to the greater durability of their antibody response, the frequency of spike-reactive B cells declined more rapidly in the SLE group after Vax2 (half-life; 95% confidence interval, calculated decay P = 0.009) but was similar to that in the HD group after Vax3. Together, these results suggest that B cell defects in SLE are responsible for reduced mRNA vaccine efficacy.

Fig. 3: Lower magnitude of antigen-specific memory B cells in the vaccinated SLE cohort.
figure 3

a, Cartoon showing the ex vivo tetramer-based detection of spike- and RBD-reactive B cells and high-dimensional flow immunoprofiling of B cells from PBMCs. b, Representative fluorescence-activated cell sorting (FACS) plots showing the gating strategy applied to characterize the total CD19+CD20+ B cells (excluding the CD20CD38hi plasma cells) binding to dual-tetrameric spike probes and tetrameric RBD probes. c,d, Quantification of the total spike-specific (c) and RBD-specific (d) B cells shown as the frequency of CD20+ B cells in the HD and SLE cohorts. Each dot represents an individual sample tested at baseline (day 0) and after receiving one (Vax1), two (Vax2) or three (Vax3) vaccine doses. Differences among groups were analyzed using multiple-group comparisons by nonparametric Kruskal–Wallis statistical testing using Dunn’s post hoc analysis in GraphPad Prism. Comparisons using pie charts and a chi-square with Fisher’s test are shown. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. S, spike; bio–SA, biotin–streptavidin; PC, plasma cell.

Anti-spike CD27 populations persist during the memory phase and expand in SLE

Despite the increasingly recognized complexity of these compartments, previous studies have largely concentrated on plasmablast and CD27+ memory responses. As different effector and memory pathways and the participation of IgDCD27 double-negative (DN) B cells may be induced in different SLE types24,35, we sought to interrogate further the expanded pool of antigen-reactive B cells and define their dynamics. The distribution of DN subsets (DN1–DN4) is an indicator of the origin and function of the corresponding B cells. Specifically, we have previously associated DN1 B cells with conventional CD27+ memory pathways36 and shown that they represent a large majority of DN cells in healthy individuals. In contrast, DN1 cells represent a much lower fraction in acute SLE and severe COVID-19 infections, in which DN2 and DN3 B cells are dominant. In these acute situations, DN2 and DN3 cells are considered extrafollicular naive-derived effector cells23,24,25,37,38. However, little is known about the contribution of DN subsets to effector and memory vaccination responses and specifically to mRNA vaccination.

Using unsupervised PaCMAP (pairwise controlled manifold approximation) and FlowSOM tools, we determined the complexity of the global B cell compartment and defined the participation of multiple B cell clusters in the anti-spike/RBD response (Extended Data Fig. 6a and Fig. 4a). In SLE, the major differences were driven by populations of B cells typically associated with the disease (for example, activated B naive, DN2, DN3 and 9G4-expressing cells24,35; Extended Data Fig. 6a and Fig. 4a). In particular, within the DN B cells, RBDspike+ B cells in the SLE group were significantly enriched for DN2/DN3 clusters (#4, 5, 25) over DN1 (cluster #11) (Extended Data Fig. 6a). Increased DN2 and spike++ DN2 populations were shared among patients with SLE, with greater frequency in those of Black ancestry (Extended Data Fig. 6b).

Fig. 4: Greater DN2 expansion in the vaccinated SLE cohort.
figure 4

a, PaCMAP and FlowSOM representations of spike++CD20+ B cells from HDs (n = 126) and SLE donors (n = 161). Samples were combined from Vax1 + Vax2 + Vax3. b, Representative FACS plots showing the characterization of spike-reactive CD20+ B cell subsets based on the expression of IgD and CD27. CD21 and CD11c markers are used to define the DN subsets further. Individual samples from the HD (Vax1, n = 23; Vax2 1–3 months, n = 22; Vax2 >3 months, n = 34; Vax3 1–3 months, n = 37; Vax3 >3 months, n = 13) and SLE (Vax1, n = 20; Vax2 1–3 months, n = 45; Vax2 >3 months, n = 51; Vax3 1–3 months, n = 24; Vax3 >3 months, n = 20) cohorts. c, Bar graphs showing the relative frequency of spike++ B cell subsets based on IgD and CD27 expression in the HD and SLE cohorts. Vertical lines indicate the s.e.m. A two-sided Mann–Whitney U test was used to calculate the significance of the SLE group compared to the HD group. d, Relative frequency of spike++ B DN cell subsets in vaccinees from the HD and SLE groups. Vertical lines indicate the s.e.m. A two-sided Mann–Whitney U test was used to calculate the significance of the SLE group compared to the HD group. e, Pie charts showing comparisons of the average sum for DN1 versus non-DN1 (DN2 + DN3 + DN4) spike++ B DN cells. A chi-square with Fisher’s test was used for significance testing. f, Reactivity of DN subsets among nonresponders and responders. A chi-square test was used for statistical comparisons. The LOS was based on median values of baseline + 2 × s.d. g, PaCMAP and FlowSOM data representing the level of expression of CXCR3 on clusters of spike++CD20+ B cells as in a. h, Dot plots representative of the CCR6 and CXCR3 expression of the total and spike++ B cells. The bar graphs show the distribution of CCR6- and CXCR3-expressing spike-reactive B cells of the HD and SLE cohorts. Individual samples from the HD (Vax1, n = 23; Vax2 1–3 months, n = 22; Vax2 >3 months, n = 34; Vax3 1–3 months, n = 37; Vax3 >3 months, n = 13) and SLE (Vax1, n = 20; Vax2 1–3 months, n = 45; Vax2 >3 months, n = 51; Vax3 1–3 months, n = 24; Vax3 >3 months, n = 20) cohorts. Vertical lines indicate the s.e.m. A two-sided Mann–Whitney U test was used to calculate the statistical significance of the B cell subset populations in the SLE cohort compared to HD frequencies, as shown in the SLE graphs. i, Pie charts showing the comparison of the total CXCR3+spike++ and CXCR3spike++ B cells, as well as relative frequencies. A chi-square with Fisher’s test was used for comparisons. When indicated, the LOD was set to logarithmic 0.001 for B cells and 0.003 for T cells. The LOS was based on median values of baseline + 2 × s.d. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. Pac blue, Pacific blue; Unsw, unswitched; B mem, B memory.

We also used a supervised two-dimensional flow cytometry approach to measure the distribution of spike-reactive B cells among previously identified parental populations defined by the expression of IgD and CD27: naive, CD27+ unswitched memory, CD27+ isotype-switched memory and IgDCD27 DN cells. DN B cells were further fractioned into four specific subsets (DN1–DN4)23,24,39 determined by the expression of CD21 and CD11c (full gating strategy; Extended Data Fig. 2a and Fig. 4b). The CD20+spike+ B cell responses to Vax1 included in both cohorts similarly large fractions of naive B cells (~40%) that rapidly contracted over subsequent vaccinations (Fig. 4c). The IgD+ unswitched memory cells also contributed to a small portion of the total antigen-induced population that rapidly contracted (Fig. 4c). The initial priming responses included significant fractions of early CD27+ switched memory cells and DN cells, the latter representing naive-derived effector responses as we had previously reported for autoreactive B cells in SLE and severe COVID-19 infections25,35,37. Notably, DN cells dominated the spike response early in SLE and remained dominant in both groups before booster vaccination, presumably reflecting memory cells induced by Vax1 and effector/activated memory cells induced by Vax2 (ref. 40). In both groups, while conventional CD27+ memory cells dominated the response following booster vaccination, DN cells represented a large fraction of the memory responses (Fig. 4c,d). In this study, DN1 strongly dominated the spike-specific responses in HDs across all time points. In contrast, in patients with SLE, DN2 cells dominated the early response to Vax1 and Vax2 and remained significantly higher relative to the HD cohort in the post-Vax3 period (Fig. 4d,e). Moreover, DN2 cells were enriched in low spike responders (below the limit of sensitivity (LOS)) (Fig. 4f). DN3 cells also contributed to different phases of the response and were significantly expanded at late time points after Vax2 and Vax3 in the SLE group (Fig. 4d).

The expression of C–C chemokine receptor type 6 (CCR6) and C–X–C motif chemokine receptor 3 (CXCR3) on spike-reactive B cells was also qualitatively different between the two cohorts (Fig. 4g–i). In the HD cohort, we observed a predominance of CCR6+spike+ B cells that expanded within subsequent vaccinations (Fig. 4g–i). In contrast, in patients with SLE, spike+ B cells were highly enriched for CXCR3+ cells (Fig. 4g–i). We further analyzed the contribution of several B cell isotypes to the anti-spike responses by examining their immunoglobulin surface expression with flow cytometry (Extended Data Fig. 6c–g). IgG responses dominated the spike reactivity (Extended Data Fig. 6c,d,g), whereas IgM and IgA memory B cells represented a smaller portion of this response (Extended Data Fig. 6c–f). Interestingly, IgM+ memory B cells were increased in SLE, particularly in the early post-Vax2 and Vax3 phases, accounting for >20% of all antigen-reactive CD20+ B cells in several patients (Extended Data Fig. 6e). Additionally, in the SLE cohort, spike reactivity was associated with a smaller and delayed expansion of IgG+ B cells upon recall doses (Extended Data Fig. 6g). Collectively, these data indicate that patients with SLE mount a diverse anti-B cell immunity upon mRNA vaccination, with greater expansion of DN2/DN3 B cells also persisting during the establishment of memory responses.

Impaired activation and persistence of anti-spike lupus T cells

We also sought to define the magnitude, kinetics and differentiation of CD8+ and CD4+ T cells upon mRNA vaccination. To this end, we used an in vitro system suitable for scoring the frequency of antigen-reactive T cells and that relies on the incubation of cells with megapools of peptides and allows their quantification using the activation-induced marker (AIM) assay6,41 (Fig. 5a and Extended Data Fig. 7a,b). Cells were stimulated with megapools of spike overlapping peptides spanning the entire protein (WA.1, spike aa 5–1,273) or with peptides from the hemagglutinin (HA) H1N1 (A/California/04/2009) protein, an unrelated control for viral T cell reactivity. Twenty-four hours after incubation, samples were analyzed to score the magnitude of antigen-reactive AIM+ cells using a combination of two surface markers (CD69 and 41BB for CD8+ T cells and CD40L and OX40 for CD4+ T cells). T helper CD4+ cells were classified based on their expression of chemokine receptors, and their polarization was further investigated in both the CXCR5 or CXCR5+ (referred to as ‘AIM+ circulating T follicular helper (cTFH)’) compartments (Fig. 5b and Extended Data Fig. 7b).

Fig. 5: Lower T cell reactivity in patients with SLE receiving SARS-CoV-2 mRNA vaccines.
figure 5

a, Schematic showing the 24-h AIM assay-based detection of antigen-reactive T cells upon incubation of PBMCs with a megapool of spike-derived peptides and the flow cytometric analysis of surface-expressed markers of activation and immune profiling. b, Representative FACS plots showing the gating strategy applied to characterize the AIM+ spike-reactive CD8+ (41BB+CD69+) T cells or AIM+ spike-reactive CD4+ (OX40+CD40L+) T cells and AIM+ spike-reactive cTFH (CXCR5+ of AIM+CD4+) cells among the CD3+ T cells. ce, Scatter plots showing the frequency of spike-specific AIM+ T cells quantified at each indicated time point in the HD and SLE cohorts for AIM+CD8+ T cells (c), AIM+CD4+ T cells (d) and AIM+CD4+ cTFH (e) cells. The vaccination time points in ce indicate the following binned time points (T), as indicated in Extended Data Fig. 1a: 0 (T0, baseline), 1 (T1–T3), 2 (T4–T5), 3 (T6–T7), 4 (T8–T9), 5 (B1–B5) and 6 (B6–B9). The number of samples is indicated as ‘Total (n)’. f, PaCMAP and FlowSOM representations of AIM+CD8+ T cells (HD, n = 137; SLE, n = 163) and AIM+CD4+ T cells (HD, n = 136; SLE, n = 169) from the HD (n = 126) and SLE (n = 161) cohorts from combined Vax1 + Vax2 + Vax3. A total of 15 clusters are indicated in the plots, and the relative marker expression and classification of the clusters are shown in Extended Data Fig. 7f,g. g, Representative dot plots showing the differentiation of AIM+ T cells using CD45RA and CCR7 expression. h, Bar plots showing the distribution of the four subsets (TN/TSCM, TCM, TEM and TEMRA) of AIM+CD8+ T cells. Individual samples from the HD (Vax1, n = 17; Vax2, n = 47; Vax3, n = 43) and SLE (Vax1, n = 12; Vax2, n = 65, Vax3, n = 38) cohorts. i, Bar plots showing the distribution of the four subsets (TN/TSCM, TCM, TEM and TEMRA) of AIM+CD4+ T cells. Individual samples from the HD (Vax1, n = 19; Vax2, n = 54; Vax3, n = 48) and SLE (Vax1, n = 20; Vax2, n = 81, Vax3, n = 45) cohorts. A two-sided Mann–Whitney U test was applied to compare each subset of T cells between the SLE and HD groups, and significance is shown in the SLE bars. When indicated, the LOD was set to logarithmic 0.001 for B cells and 0.003 for T cells. The LOS was based on median values of baseline + 2 × s.d. Vertical lines indicate the s.e.m. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. MP, megapool; TN, naive T cells; TSCM, stem cell-like memory T cells; TCM, central memory T cells; TEMRA, TEM cells reexpressing CD45RA.

Lower T cell responses were observed in the SLE cohort, with impaired priming of AIM+CD8+ T cells (Fig. 5c) and lower levels of both AIM+CD8+ and AIM+CD4+ T cells at the late memory and recall phases (Fig. 5c–e and Extended Data Fig. 7c–e). The overall fold reduction in the SLE group compared to the HD group was 6.71 (AIM+CD8+ T cells) and 3.15 (AIM+CD4+ T cells) at Vax2 and 3.85 (AIM+CD8+ T cells) and 2.92 (AIM+CD4+ T cells) at Vax3.

Unsupervised PaCMAP and FlowSOM cluster analyses were informative of significant differences in terms of T cell polarization, with T cells in the SLE cohort characterized by a reduction in effector memory T (TEM) cell subsets, also expressing CCR4 and/or CCR6 (CD8+ T cell clusters #8 and 12–14, CD4+ T cell clusters #1–3, 7 and 8) (Fig. 5f and Extended Data Fig. 7f,g). Two-dimensional flow cytometry comparisons confirmed that the SLE anti-spike T cell responses were less represented in the TEM pool over three doses of vaccine (Fig. 5g–i) and were distinguished in their SLE cTFH compartment, with an initial skewing of primed AIM+ cTFH cells into CCR6+ TFH17 cells (Extended Data Fig. 8a) and a general reduction in the magnitude of the SLE AIM+ cTFH pool upon memory responses, especially after Vax2 (Fig. 5e).

Notably, HA-reactive memory T cells were detected at normal levels in patients with SLE (Extended Data Fig. 8b), although the AIM+ HA CD8+ pool still failed to generate normal TEM cells (Extended Data Fig. 8c), suggesting that CD8+ T cell defects might be mediated by associated lupus-disease defects42. These results suggest that anti-spike T cell defects in SLE might be largely a result of inefficient mRNA activity and/or a property of vaccine- versus infection-induced T cell immunity.

Poor vaccine-mediated responses associate with an SLE extrafollicular immune signature

To investigate the influence of B cell endotypes on different vaccine responses, we used the total RBD-reactive IgG levels to classify all vaccinees into three groups of responders: negative/low (VNL), medium (VM) or high (VH) vaccine responders (Fig. 6a). As expected, RBD IgG titers directly correlated with the potency of WA.1 neutralization (Fig. 6b). Vaccinees with SLE who received one or two vaccine doses were enriched for negative/low responders, and their neutralizing IgG potency upon Vax2 was still significantly lower than that in HDs. While the booster dose improved the responses in the SLE cohort, only 78% reached high antibody titers relative to 97% in the HD cohort (Fig. 6a). We then tested the hypothesis that, in our SLE cohort, a predisposition to strong extrafollicular immune responses might be responsible for lower immunogenicity of the mRNA vaccine. To address this question, we assessed patients for circulating cellular surrogates of extrafollicular activity identified in previous studies of SLE and acute COVID-19 infections25,35,37. Based on these studies, we created an ‘extrafollicular activity score’ that included markers proposed to represent decreased GC activity (low B DN1 frequency) and low activated cTFH (act cTFH, CXCR5+PD-1+CD38+) frequency, together with markers of extrafollicular activation, including increase in B DN2 and circulating plasmablasts, as well as expansions of CXCR5 peripheral activated T helper (act TPH, CXCR5PD-1+CD38+) cells43,44 (Fig. 6c and Extended Data Fig. 9a). We observed that higher extrafollicular scores were indeed associated with VNL groups, with strong overrepresentation of its components in the SLE cohort, where they negatively correlated with vaccine responsiveness (Fig. 6d). Factors contributing to vaccine responses, such as age, sex or race, did not appear to drive a strong bias in mRNA immunogenicity and vaccine responsiveness (Extended Data Fig. 9b–e).

Fig. 6: Characterization of our cohort of vaccinees based on vaccine responsiveness and the associated extrafollicular-like signature.
figure 6

a, Mean values of RBD IgG titers based on the classification of three groups: VNL (MFI 0–10,000), VM (MFI 10,000–100,000) and VH (MFI >100,000); the proportion of responders is shown for each group (HD: filled squares, SLE: empty triangles) and vaccination time point. The number of samples analyzed (n) is shown at the bottom of the plots. b, Plasma log10(NT50) values detected for the pseudoviral neutralization of the WA.1 strain and based on the three groups of vaccine reactiveness as in a, at the Vax2 and Vax3 time points. The red lines in the plots indicate the LOS. The range of response (negative, low, medium, high) is indicated in the graphs. Each dot in the box plots represents an individual sample tested. Horizontal lines indicate the median. The proportion of positive responders is shown as the frequency indicated for each group and compared between groups of responders and time points (a two-sided Mann–Whitney U test was applied to compare the groups in the HD and SLE cohorts). c, Simple model showing the proposed B cell differentiation alongside the extrafollicular or GC pathways. Cell population frequencies were used to mimic a circulating B and T cell extrafollicular-derived signature based on reduced frequency of CD21+CD11c DN1 cells (<50%) and act cTFH (CXCR5+PD-1+CD38+) cells (<1.4%) and increased frequency of CD21CD11c+ DN2 cells (>20%), CD20CD38hi plasmablasts/plasma cells (>3%) and act TPH (CXCR5PD-1+CD38+) cells (>4%). d, Variables related to the extrafollicular signature were scored and summed in each sample tested for the VNL, VM and VH groups in the HD and SLE cohorts. Intracohort and intercohort statistical comparisons were performed with a chi-square test. eg, Bubble plots showing the correlation of cellular immune responses and RBD IgG titers. The red lines in the plots indicate the LOS. The frequencies of spike++ B cells (e), spike++RBD+ B cells (f) and AIM+ cTFH cells (g) are shown. h, Bar graphs related to eg showing the quantitation of nonresponders (black filled bars, based on the LOS) and responders (white filled bars) separated for each vaccination time point and group (VNL: black line, VM: light blue line, VH: pink line). A chi-square test was used for statistical comparisons. The LOS was based on median values of baseline + 2 × s.d. Not significant, P > 0.05; *P < 0.05; ***P < 0.001; ****P < 0.0001. SHM, somatic hypermutation; EF, extrafollicular; SLPB, short-lived plasmablast; LLPC, long-lived plasma cell; ND, not determined; NS, not significant.

We next asked whether the qualitative assessment of serological reactivity was correlated to the magnitude of antigen-specific memory B and T cells. A strong correlation was detected between negative and low antigen-specific B and T cell responses and the VNL group (Fig. 6e–h and Extended Data Fig. 9f,g). Notably, a great lack of immune memory responses in the B and T cell compartments was uniquely observed in a group of VNL patients with SLE who received two mRNA vaccine doses (Vax2) (Fig. 6e–h and Extended Data Fig. 9f,g). These results confirm defective humoral and cellular immunity in poor vaccine responders and their association with extrafollicular endotypes.

Poor vaccine responses and high extrafollicular scores linked to BAFF inhibition in SLE

We next investigated cellular variables within the different SLE treatment groups. Integrating our immunophenotyping postvaccination data through principal component analysis (PCA), we segregated the HD and SLE cohorts based on underlying immunological-associated features (Fig. 7a and Extended Data Fig. 10a). The results indicated that the general immune cell composition remained distinct between the SLE and HD cohorts throughout the vaccine-mediated responses. Overlaying patient metadata onto the PCA plot revealed that patients receiving anti-BAFF therapy (belimumab) were the most distant group from both HDs and patients with SLE receiving other classes of SLE therapy (Fig. 7a, Extended Data Fig. 10b and Supplementary Table 2). Comparisons of vaccinated HDs and patients with SLE subgrouped by treatment class confirmed that unique extrafollicular signatures were globally associated with the SLE diagnosis. Features included a stronger extrafollicular B cell signature with an expansion of activated naive cells, DN2 cells and ASCs (for example, plasma cells) in the B cell compartment, as well as reduced cTFH cells (Extended Data Fig. 10c–h).

Fig. 7: Impact of SLE treatment on vaccine-mediated responses and enrichment of poor responders in patients receiving belimumab.
figure 7

a, Unsupervised PCA analysis showing separation of the HD and SLE cohorts based on immunophenotypic variables. b, Luminex-based detection of RBD IgG-binding serum antibodies (net MFI values) in the HD cohort and subgroups of patients with SLE based on their treatment. The number of samples analyzed (n) is shown at the bottom of the plots. c, Proportion of patients with SLE based on their treatment among the three groups (VNL, VM and VH) of vaccine responders. d, Table with pie charts showing the percentage of VNL, VM and VH in the HD and SLE groups, as well as the relative proportion of each SLE subgroup/treatment responsiveness of the total SLE cohort. e, Neutralizing titers based on the SLE treatment group for the WA.1 strain and distribution of responders shown as a frequency of the total samples for each column. f, Cellular analysis of spike reactivity for spike++ B cells, calculated as the frequency of viable cells. g, Relative frequency of spike-reactive DN B cell populations for the HD cohort and SLE subgroups. Vertical lines indicate the s.e.m. h, Pie charts showing comparisons of the average sum for DN1 (green) versus non-DN1 (DN2 + DN3 + DN4) (white) spike++ B DN cells; the relative frequencies are shown for all vaccinated samples combined from the HD cohort and SLE subgroups. A chi-square with Fisher’s test was used for significance testing. i, AIM+ cTFH cells shown for each vaccine group and SLE subgroup. Each dot represents an individual sample. Statistical comparisons in b, e, f, h and i were performed with an unpaired, two-sided Mann–Whitney U test. When indicated, the LOD was set to logarithmic 0.001 for B cells and 0.003 for T cells. The LOS was based on median values of baseline + 2 × s.d. Not significant, P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001. j, Distribution of nonresponders calculated as the fold change of the cumulative percentage of nonresponders (negative values) for each of the indicated categories tested at Vax1–Vax3 (RBD-specific IgG, spike++ B cells and cTFH cells) and Vax2–Vax3 (WA.1 nAb). For boxplots in (b) and (c), dots represent individual samples tested; horizontal lines indicate the median. HCQ, hydroxychloroquine; AZA, azathioprine; MTX, methotrexate; MMF, mycophenolate mofetil; BLM, belimumab.

The multivariate analysis suggested that not only disease-associated immunophenotype characteristics but also lupus-specific medications might distinguish vaccine-mediated immune responses. Therefore, we sought to explore whether there was a meaningful correlation between poor vaccine responses and specific SLE treatments. Humoral and cellular responses were diverse and changed dynamically in each SLE subgroup. Thus, the subgroup of patients with SLE receiving belimumab was enriched for the category of poor vaccine responders (VNL), whereas the other subgroups (patients receiving mycophenolate mofetil, azathioprine or methotrexate) were similarly distributed among the three vaccine groups, with the hydroxychloroquine subgroup being overrepresented among good vaccine responders (Fig. 7b–d). Disease activity score (measured as the SELENA-SLEDAI (Safety of Estrogens in Lupus National Assessment-SLE Disease Activity Index) score) differed significantly between the SLE subgroups, with the lowest score in the hydroxychloroquine group (Extended Data Fig. 10i); however, it did not seem to influence vaccine-mediated antibody and B cell responses (data not shown).

The total RBD-specific IgG levels also reflected the nAb potency and breadth in the SLE subgroups (Fig. 7e and Extended Data Fig. 10j).

From a cellular standpoint, poor responses correlated with a general reduction in total circulating B cells (Extended Data Fig. 10c). The overall spike-specific B cell responses were largely unaffected in hydroxychloroquine-treated patients across all vaccine doses (Fig. 7f). In contrast, all other treatment subgroups had significantly impaired responses at Vax1. Notably, subsequent vaccine doses induced normal responses in the group treated with mycophenolate mofetil. Antimetabolite treatments with azathioprine or methotrexate as well as belimumab treatment induced the poorest levels of response, which remained greatly diminished even after three doses. The belimumab group had the lowest frequency of spike-specific B cells, albeit not significantly different from the azathioprine/methotrexate group, and contained the largest fraction of patients with spike-specific B cells below the limit of detection (LOD) (Fig. 7f).

From a qualitative standpoint, antigen-specific B cells shifted in all treatment groups except for the belimumab subgroup, from an early dominance of naive and DN cells to a predominance of CD27+ memory B cells. Consistent with its preferential impact on naive cells relative to memory cells27, belimumab treatment led to the largest accumulation of CD27+ memory cells (Extended Data Fig. 10k); this is unlikely to depend on enhanced cross-reactivity with the CCCs, which appeared to be proportionally small and not dissimilar to that in the other groups (Extended Data Fig. 5c).

In contrast, DN cells remained the majority of antigen-specific B cells in the azathioprine/methotrexate subgroup after Vax3. Within the heterogeneous DN compartment (Fig. 7g), there was a gradual increase in the contribution of DN1 responses, which accounted for approximately 50% of all spike+ DN B cells after three doses in the HD cohort as well as in the hydroxychloroquine and azathioprine/methotrexate SLE subgroups. However, non-DN1 cells represented >75% of spike+ DN cells in the mycophenolate mofetil and belimumab groups (Fig. 7h).

T cell responses were broadly reduced in patients with SLE, with a more pronounced and general loss of CD8 reactivity against the spike (Extended Data Fig. 10l) and low CD4+ T cell (Extended Data Fig. 10l) and memory cTFH cell (Fig. 7i) responses in the poor B cell responder groups.

Overall, the most profound reduction or lack of vaccine efficiency, measured as a combined activity of serological and cellular-mediated responses, was observed in patients with SLE receiving anti-BAFF treatment at the time of the initial vaccination (and remained treated over the course of vaccine sample collections); this group contained the largest proportion of nonresponders (Fig. 7j). Notably, consistent with the preferential impact of belimumab on naive B cell activation and survival, all belimumab-treated patients failed to respond to the priming dose (Fig. 7f) and were characterized by significantly reduced potency and breadth of neutralization (Fig. 7e and Extended Data Fig. 10j) upon subsequent dosing. Additionally, these patients showed significantly reduced magnitude of memory antigen-specific B cell (Fig. 7f) and spike-specific cTFH (Fig. 7i) responses.

Discussion

Clinical efficacy and immune correlates of mRNA vaccination have been amply tested in the healthy population and in patients with cancer33,45 or solid organ transplantation46,47,48. In contrast, the humoral and cellular responses to these vaccines are poorly understood in patients with SLE in whom both components can be compromised by the autoimmune disease itself and by multiple immunosuppressive treatments.

Our study provides an in-depth antibody and cellular analysis of a large cohort of patients with SLE, most of whom were of Black ancestry (n = 79, 68% Black). Globally, patients with SLE showed reduced seroconversion rates and a generalized reduction in ACE2-blocking activity that was uncoupled from anti-RBD IgG titers, suggesting some caution in assessing vaccine efficacy simply based on anti-spike/RBD titers. In harmony with lower competitiveness, the neutralizing power and breadth of neutralization of the SLE plasma samples were significantly lower than those in the control group even after full seroconversion. While the mechanistic basis of these qualitative antibody defects remains to be determined, we propose that these features could be explained by defective affinity maturation, possibly due to aberrant GC activity and/or dominant extrafollicular activity49,50,51. This conclusion is supported by direct SPR measurements of lower avidity of the SLE anti-spike antibodies.

Notably, a slower decline in nAb titers observed after booster vaccination in patients with SLE, an opposite trend to the shorter durability of anti-spike memory B cell responses, suggests that the lupus milieu may facilitate the generation of long-lived plasma cells and interfere with memory B cell formation. Overall, our study provides new insights into the impact of abnormal B cell biology on mRNA vaccine responses. We had previously shown that, in Black patients with severe SLE, despite strong preexisting autoimmune memory, disease flares are characterized by an influx of newly activated naive cells whose differentiation through an extrafollicular pathway generates a large fraction of the ASCs expanded during active disease24,35. Those studies identified effector DN2 B cells downstream of activated naive B cells, epigenetically poised in SLE to differentiate into ASCs52. From the analysis of antigen-specific anti-spike B cells, one notable result is the demonstration of the contribution of DN2 cells to both effector and memory responses. This finding indicates the limitations of ascribing memory function based on phenotypic markers shared by effector cells, including loss of CD21 expression and positive expression of CD11c. Moreover, it strongly suggests the ability of human extrafollicular responses to generate a separate memory cell compartment, a phenomenon already established in mice. In keeping with the accentuation of the extrafollicular pathway in severe SLE and its potential contribution to a memory compartment, both components of extrafollicular responses previously described in SLE and severe COVID-19 infections23,25, DN2 and DN3 cells, dominated the effector phase of the priming response and remained a large part of spike-specific B cells several months after booster vaccination in the absence of intervening infection. In contrast, DN1 cells, presumed to represent early GC memory24, dominated normal responses across all vaccination time points. Of great interest, within the SLE cohort, a high extrafollicular index score strongly correlated with lower antibody responses. Combined, our data are consistent with a model that predicts that extrafollicular B cell SLE endotypes would promote decreased antibody responses with reduced neutralization activity presumably based on defective affinity maturation.

Also indicative of the SLE milieu with high levels of type II interferon in association with enhanced extrafollicular responses53, antigen-reactive B cells in patients with SLE were significantly enriched for CXCR3-bearing cells53. Conversely, CCR6+ cells devoid of CXCR3 dominated the HD responses, a pattern that could promote an enhanced GC origin of memory cells in normal responses. In contrast, the SLE profile could promote relocation of tissue CXCR3+ memory cells to sites of viral reinfection.

In addition to disease-related determinants, the response to vaccination in SLE is also modulated by treatment. Previous studies, restricted to antibody assessment, have predictably shown that B cell- and plasma cell-targeting agents used in the treatment of SLE can dampen antibody-mediated responses and the global B cell pool33,45,54. Other immunomodulatory drugs, such as mycophenolate mofetil, have been shown to reduce vaccine efficacy in some vulnerable populations such as patients with autoimmune rheumatic diseases16,17 or solid organ transplant recipients46,47. In our SLE cohort, we also observed reduced seroconversion associated with treatment with mycophenolate mofetil. Yet, in contrast to findings in kidney transplant recipients, the second and third doses were able to rescue the initially deficient responses in these patients55. This discrepancy can be due to both disease-specific features, the dose of mycophenolate mofetil administered and cotreatments with other potent immunosuppressive drugs.

Notably, within the SLE cohort, the most profound and persistent deficit in vaccine efficacy was observed in patients treated with belimumab, characterized by a reduction in de novo generation of anti-spike B cells and spike-reactive cTFH cells. Combined, our data suggest that the role of BAFF in the generation of cTFH cells and in the affinity maturation of GC B cells could explain how belimumab treatment results in poor antibody ACE2 competitiveness, neutralization and breadth potency56,57.

Globally, the knowledge acquired in this study should form the basis for new strategies to enhance the efficacy and durability of mRNA vaccinations, including modifications of vaccine dosing and timing and modulation of the magnitude and/or timing of the administration of immunosuppressive agents.

Our study has some limitations, as our cohorts were not perfectly sex- and race-matched due to the recruitment limitations imposed by the pandemic isolation requirements and limited access to a broader population of HDs. Nevertheless, we believe that our results could contribute to the understanding of mRNA vaccine responses in general and in particular in patients with autoimmune diseases and other immune conditions with underlying B cell defects or immunomodulating treatments.

Methods

Human participants

This research was approved by the Emory University Institutional Review Board (Emory IRB nos. IRB000057983 and IRB000058515) and performed in accordance with all relevant guidelines and regulations. Blood draws were obtained after acquiring written informed consent from the participants. Participants were compensated for their time and interest in the study. Healthy individuals (n = 64) and patients diagnosed with SLE (n = 79) were recruited from Emory University Hospital, Emory University Hospital Midtown and Emory/Grady (all in Atlanta in the United States). The demographics of the HD and SLE cohorts and the medications used by patients with SLE are listed in Supplementary Tables 1 and 2. Study data were collected and managed using the REDCap electronic data capture tool (a secure web platform for building and managing online databases and surveys) hosted at Emory University. All individuals enrolled in this study were considered naive to SARS-CoV-2 infections based on the absence of self-reported symptoms and/or negative PCR test results. All tested samples were screened for the absence of SARS-CoV-2 nucleocapsid-reactive IgG, and nucleocapsid-positive samples were excluded from the study (Extended Data Fig. 2a,b).

PBMC isolation and serum and plasma collection

Peripheral blood samples were collected in green-top (Vacutainer) sodium heparin tubes. Red-top tubes (Vacutainer) were centrifuged for 10 min at 800g to collect the serum. Undiluted plasma was collected after centrifugation of the blood for 10 min at 500g. Serum and plasma aliquots were stored at −20 °C. Next, blood samples were diluted (1:2) with PBS, and PBMCs were isolated by Ficoll density gradient centrifugation at 1,000g for 10 min. PBMCs were washed twice with R10 complete medium and lysed with ACK lysis buffer. Viability was assessed using trypan blue exclusion, and live cells were counted using an automated hemocytometer. Frozen cells were stored at −80 °C in FBS/10% DMSO.

Flow cytometry

PBMCs in frozen vials were thawed, washed and centrifuged at 800g for 5 min and then resuspended in warm R10 complete medium at a final concentration of 20 × 106 cells per ml. Cell suspensions were divided into three parts to perform (1) AIM assays (~1 × 106 cells), (2) B cell tetramer staining (~4 × 106–8 × 106 cells) and (3) T cell staining (~2 × 106–4 × 106 cells). A mixture of diluted antibodies was prepared in staining buffer (PBS/2% FCS, 1 mM EDTA) supplemented with Super Bright Complete Staining Buffer and added to the samples in a 96-well round-bottom plate at a final volume of 50 μl per well. After each step, antibody staining was blocked with a wash in staining buffer (~100 μl) and centrifugation of the plate at 800g for 5 min. For the B cell immunophenotype, after incubation with the tetramers for 1 h at 4 °C, cells were washed and stained with a mixture of anti-immunoglobulins (anti-IgD + anti-IgM + anti-IgA + anti-IgG) for ~15 min at room temperature (RT) in the dark. The cells were then incubated with the cocktails of the remaining antibodies for ~40 min at RT in the dark. After washing and centrifugation, cells were stained with L/D Zombie NIR (diluted at 1:500 in PBS) for 10 min at RT in the dark. Similarly, for the T cell immunophenotype, samples were stained with the antibody mixture for ~40 min at RT in the dark, and viable cells were detected with L/D Zombie NIR. Cells were resuspended in ~180 μl staining buffer, kept on ice and immediately analyzed on a 5L Cytek Aurora flow cytometer using Cytek SpectroFlo software. The extrafollicular score was determined by defining ‘normal’ population frequencies ±1 or ±2 s.d. and based on the average flow cytometry values for B DN1 cells, B DN2 cells, plasmablasts/plasma cells, act cTFH cells and act TPH cells in the HD group, as shown in Extended Data Fig. 9e. The combined score was calculated giving a value of 1 for positivity of each of the five variables tested for each donor and creating a sum of those positive values to reach a range of 0 (none of the cellular variables fit the extrafollicular score) to 5 (all cellular variables fit the extrafollicular score) and intermediate values of 1–4, according to the sum. Flow cytometry data were analyzed using FlowJo v10.8.0.

Detection of tetramer-binding B cells

Antigen-specific B cells were detected using tetramer probes. Biotinylated spike and RBD proteins (R&D Systems) were multimerized with fluorescently labeled streptavidin (SA) for 1 h at 4 °C. Full-length spike protein was mixed with SA-BV421 using ~100 ng spike and ~20 ng SA for each sample (~4:1 molar ratio). RBD was mixed with SA-AF647 using ~25 ng RBD and ~12.5 ng SA (~4:1 molar ratio). SA-PerCP was used as a decoy probe. After 1 h, all tetramers were mixed in free d-biotin (5 μM, Avidity) to minimize cross-reactivity. PBMCs were incubated for 1 h at 4 °C with the mixture of tetramers, washed and stained with surface markers, and labeled for viability with L/D Zombie NIR (1:500) for ~10 min before being acquired with the 5L Aurora (Cytek).

AIM assay

AIM assay was performed as follows. Briefly, PBMCs were counted and adjusted to 20 × 106 cells per ml in complete medium (RPMI 1640/5% human AB serum supplemented with GlutaMAX, nonessential amino acids, sodium pyruvate and penicillin–streptomycin). Antigen-specific T cell responses were assessed by incubating 1 × 106 cells with megapools of peptides (15-mers overlapping by 11 aa) encompassing the sequences of human pathogens: SARS-CoV-2 WA.1 full spike (aa 5–1,273, Miltenyi Biotec) or HA (H1N1, strain swl A/California/04/2009, Miltenyi Biotec). Cells were incubated in a 96-well U-bottom plate in a final volume of 200 μl. To detect extracellular CD40L expression, we preincubated cells with an anti-human CD40 antibody (Miltenyi Biotec, pure functional grade, cat. no. 130-094-133) used at 0.5 μg ml−1 for 15 min at 37 °C before stimulation. Cells were then stimulated with each megapool of spike or HA (used at 1 μg ml−1). Polyclonal stimulation of cells was performed with TCR triggering by staphylococcal enterotoxin B (1 μg ml−1) injection, and the stimulated cells were used as a positive control. Unstimulated cells at the same density were incubated in complete medium and used as background signals for the quantification of AIM+ cells. Cells were stimulated for ~24 h before washing and staining for flow cytometry. Cells were analyzed on a 5L Aurora flow cytometer (Cytek). Data in the graphs are shown as background-subtracted (control) values, and negative values are shown as 0.003 in the log10-scale graphs.

ELISA detection of human coronavirus (CCC) IgG

To detect IgG antibodies to the four seasonal CCCs, we coated 96-well ELISA half-area plates (Corning) overnight with 2 μg ml−1 recombinant spike protein from four separate human coronavirus strains (OC43, NL63, 229E and HKU1). Plates were blocked with PBS, 1% casein and 0.1% Tween 20 for 30 min at RT. Serially diluted (at 1:3 fold) heat-inactivated serum or plasma samples were added for 2 h at RT. After four washes with DPBS/0.1% Tween 20 and 1× DPBS, goat anti-human IgG-HRP was added to each well (1:5,000 dilution), and plates were incubated for 1 h at RT. Finally, signals were developed with ready-to-use tetramethylbenzidine solution and stopped with stop solution. Plates were read at 450 nm, and raw optical density (OD) data were expressed as ‘endpoint titers’ using a cutoff value of 0.2.

Carbodiimide coupling of microspheres to SARS-CoV-2 antigens and Luminex proteomic assays for measurement of anti-antigen antibody

This analysis was carried out as previously described. Briefly, five SARS-CoV-2 proteins were coupled to MagPlex microspheres of different regions (Luminex). The nucleocapsid (cat. no. Z03480, expressed in Escherichia coli) and S1-RBD (cat. no. Z03483, expressed in HEK293 cells) proteins were purchased from GenScript. The S1 domain (aa 16–685, cat. no. S1N-C52H2, expressed in HEK293 cells), S1-NTD (aa 13–303, cat. no. S1D-C52H6, expressed in HEK293 cells) and S2 domain (cat. no. S2N-C52H2, expressed in HEK293 cells) proteins were purchased from ACROBiosystems. Each protein was expressed with an N-terminal His6-tag to facilitate purification (>85% purity) and appeared as a predominant single band on SDS–PAGE analysis. Coupling was carried out at 22 °C following standard carbodiimide coupling procedures. The concentrations of coupled microspheres were confirmed using a Bio-Rad T20 cell counter. Approximately 50 μl of the mixture of coupled microspheres was added to each well of 96-well clear-bottom black polystyrene microplates (Greiner Bio-One) at a concentration of 1,000 microspheres per region per well. All wash steps and dilutions were accomplished using 1% BSA/1× PBS assay buffer. Serum samples were assayed at a 1:500 dilution and surveyed for antibodies to the nucleocapsid, S1, S2, NTD and RBD proteins. After incubation for 1 h in the dark on a plate shaker at 800 rpm, the wells were washed five times with 100 μl assay buffer using a BioTek 405 TS plate washer and then applied with 3 μg ml−1 PE-conjugated goat anti-human IgA, IgG and/or IgM (Southern Biotech). After 30 min of incubation at 800 rpm in the dark, the wells were washed three times with 100 μl assay buffer, resuspended in 100 μl assay buffer and analyzed using a Luminex FLEXMAP 3D instrument (Luminex) running xPONENT 4.3 software at an enhanced photomultiplier tube setting. The MFI using combined or individual detection antibodies (anti-IgA, anti-IgG or anti-IgM) was measured using the Luminex xPONENT software. The background value of the assay buffer was subtracted from each serum sample result to obtain the net MFI (MFI minus background) value.

RBD competitive ELISA

ELISA plates (96-well half-area, Corning, #3690) were precoated overnight with 2 μg ml−1 recombinant human ACE2 in PBS at 4 °C. The plates were blocked with 1% casein for 30 min at 37 °C. Serially diluted plasma and serum samples were mixed with RBD mouse Fc-tagged antigen (Sino Biological, final concentration 20 ng ml−1) for 30 min at 37 °C, and the mixture was then added to the plates for 30 min at 37 °C. The plates were washed with PBS/0.1% Tween 20, and RBD binding was revealed using secondary goat anti-mouse IgG (Southern Biotech, #1031-05, 1:5,000 in PBS). The plates were incubated for 30 min at 25 °C; after washing, 40 μl tetramethylbenzidine substrate was added, and developed plates were blocked with 40 μl stop solution and read at 405 nm with an ELISA reader. The percentage of inhibition was calculated as follows: (1 − (OD sample − OD negative control)/(OD positive control − OD negative control)) × 100.

Pseudoviral in vitro neutralization assay

Neutralization activities against the SARS-CoV-2 wild-type (WA.1), Delta (B.1.617.2) and Omicron BA.1 strains were measured in a single round of infection assay with pseudoviruses, as previously described. Briefly, for the production of the SARS-CoV-2 wild-type, Delta and Omicron pseudoviruses, an expression plasmid bearing codon-optimized SARS-CoV-2 full-length spike plasmid (parental sequence Wuhan-1, GenBank accession no. MN908947.3) was cotransfected into HEK293T cells (ATCC, #CRL-11268) with plasmids encoding nonsurface proteins for lentivirus production and a lentiviral backbone plasmid expressing a Luciferase-IRES-ZsGreen reporter, HIV-1 Tat and Rev packing plasmids (BEI Resources, NR-53818) and pseudoviruses harvested 48 h after transfection; then, titration was performed. Pseudoviruses were mixed with serial dilutions (1:50 to 1:328,050) of plasma, incubated for 1 h for the reaction at 37 °C in a 5% CO2 incubator and then added to monolayers of ACE2-overexpressing 293T cells (BEI Resources, NR-52511) in duplicate. Forty-eight hours after infection, cells were lysed, luciferase was activated with the Luciferase Assay System (Bright-Glo, Promega), and the amount of light produced (in relative light units) was measured on a synergy Biotek reader. Statistical analysis was performed using GraphPad Prism 9.0 for the determination of ID50 (median infectious dose) values through a dose–response curve fit with nonlinear regression.

SPR analysis of antibody binding kinetics to SARS-CoV-2 spike proteins

The steady-state equilibrium binding of post-SARS-CoV-2-vaccinated human polyclonal samples was monitored at 25 °C using a ProteOn SPR system (Bio-Rad). The purified recombinant SARS-CoV-2 spike RBD protein was captured to a GLC sensor chip with 300 resonance units (RU) in the test flow channels. Serial dilutions (10-, 50- and 250-fold) of freshly prepared samples in BSA–PBST buffer (PBS pH 7.4 with Tween 20 and BSA) were injected at a flow rate of 50 µl min−1 (contact duration 240 s) for association, and disassociation was performed over a 1,200-s interval. Responses from the protein surface were corrected for the response from a mock surface and for responses from a buffer-only injection. All SPR experiments were performed twice. In these optimized SPR conditions, the variation for each sample in duplicate SPR runs was <7%. Antibody off-rate constants, which describe the stability of the antigen–antibody complex (that is, the fraction of complexes that decays per second in the dissociation phase), were determined directly from the interaction of human polyclonal samples with recombinant purified SARS-CoV-2 RBD protein using SPR in the dissociation phase only for sensorgrams with maximum RU in the range of 10–150 RU and calculated using the Bio-Rad ProteOn manager software for the heterogeneous sample model as previously described. Off-rate constants were determined from two independent SPR runs.

Unsupervised flow cytometry data analysis

For high-dimensional visualization of B and T cell flow cytometry data, PBMC samples were downsampled to 200,000 spike++ B cell and 30,000 AIM+ T cell events. PaCMAP was performed on the samples in https://www.omiq.ai. Unsupervised clustering of PaCMAP populations was done using FlowSOM. Following the initial quality control exclusion, PBMC samples were used to generate the respective PaCMAP plots. Comparisons of the resulting cluster frequencies were done using the EdgeR plug-in function. PCA plots were generated in R v3.6.2 (released on 12 December 2019) using the ‘ggbiplot’ library. Custom plotting was performed using the ‘ggplot2’ library for base analysis, and plots were postprocessed in Adobe Illustrator. Bubble plots were generated in R v4.3.3 (released on 29 February 2024) using the ‘ggplot2’ and ‘dplyr’ libraries.

Half-life and durability analysis

Immune responses, starting 42 days after the second and third mRNA vaccinations, were analyzed using linear mixed-effect models with the log immune response as the dependent variable and time as the independent variable. Models for patients with SLE, HDs and combined donors included population-level fixed effects and individual-level random intercepts. Statistical significance of fixed-effect coefficients was assessed using the Wald test. Those with a maximum response less than or equal to the 95th percentile of the baseline and prepandemic samples and data associated with unexpected greater than twofold increases in NTD IgG were excluded. Models were fit using the lmer function from the lme4 package and the R programming language.

Statistical analysis

Statistical analysis was carried out using Prism v.9.5.1, v.10.2.2 and v10.0.3 (GraphPad Software). For each experiment, the type of statistical testing, summary statistics and levels of significance can be found in the figures and corresponding legends. Levels of significance are indicated as follows: *P < 0.05, **P < 0.01, ***P < 0.001 and ****P < 0.0001.

Reporting summary

Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article.