We examined the role of circulating autoantibodies in the pathogenesis of pemphigus vulgaris by p... more We examined the role of circulating autoantibodies in the pathogenesis of pemphigus vulgaris by passively transferring IgG fractions from five patients with pemphigus vulgaris into neonatal Balb/c mice, in doses of 1.5 to 16 mg per gram of body weight per day. Cutaneous blisters and erosions with the histologic, ultrastructural, and immunofluorescence features of pemphigus occurred in 39 to 55 mice given intraperitoneal injections of IgG from patients with pemphigus and in none of 58 control mice given normal human IgG. IgG fractions with high titers of pemphigus antibodies were most effective in inducing disease, and this effect was dose dependent. Titers of circulating IgG in mouse serum closely correlated with the extent of disease induced (P less than 0.002). This study strongly supports the proposed role of pemphigus autoantibodies in the pathogenesis of pemphigus vulgaris in human beings and demonstrates that pemphigus can be passively transferred to laboratory animals.
Bullous pemphigoid (BP) is an autoimmune skin disease that is characterized by the presence of su... more Bullous pemphigoid (BP) is an autoimmune skin disease that is characterized by the presence of subepidermal blisters resulting from a disruption of the adhesive interactions between basal keratinocytes and the cutaneous basement membrane. Autoantibodies from patients suffering from this disorder recognize two epidermal antigens, BP180 and BP230, both of which have been localized to the hemidesmosome, a transmembrane structure of stratified, squamous epithelia that functions in cell-matrix adhesion. In the present study we report the primary structural analysis of BP180 based on the sequence of a series of overlapping cDNA clones encompassing 4,669 bases of the BP180 transcript. A polymerase chain reaction-based protocol was used to confirm the contiguity of the cDNA segments. This cloned portion of the BP180 transcript was found to contain one long open reading frame (ORF) 4.596 bases in length. This ORF encodes a polypeptide of 155,000 Daltons with an isoelectric point of 9.7. The carboxy-terminal half of BP180, a stretch of 916 amino acids, consists of 15 collagen domains of variable length (15 to 242 amino acids) that are separated from one another by short stretches of non-collagen sequences. Located 76 amino acids upstream of the collagenous region is a putative transmembrane domain, a structural feature that distinguishes BP180 from all of the well-characterized members of the collagen family. This membrane-spanning domain is predicted to function as a signal-anchor sequence, directing the C-terminal collagenous segment of this protein to the exterior of the cell. The putative intracellular domain is highly basic with an isoelectric point of 10.37. This molecular analysis predicts that the BP180 antigen is an integral membrane protein of the hemidesmosome that contains a long extracellular collagenous tail. This combination of structural features suggests that BP180 may function as a cell-matrix adhesion molecule, with the collagenous region acting as a potential site of interaction with basement membrane components. Autoantibody-mediated disruption of such an adhesive interaction may play a critical role in the development of sub-epidermal blisters in BP patients.
Endemic pemphigus foliaceus, or fogo selvagem, is an autoimmune blistering skin disease caused by... more Endemic pemphigus foliaceus, or fogo selvagem, is an autoimmune blistering skin disease caused by IgG autoantibodies to a desmosome-associated glycoprotein. We studied the IgG subclasses with autoantibody activity in serum from 29 patients with active disease and in the skin lesions of 18 patients by immunofluorescence, using IgG-subclass-specific monoclonal antibodies. The predominant disease autoantibodies present in all patients were of the IgG4 subclass. IgG1 and IgG2 autoantibodies were detected in low titer in the 29 patients: IgG1 in 23 patients and IgG2 in 9. IgG3 autoantibodies were not detected in the serum of any patient. Direct immunofluorescence testing of skin lesions showed a preferential deposition of IgG4 on the keratinocyte surface. The pathogenic effect of IgG4 was demonstrated by the passive transfer of fractions containing IgG4 autoantibodies from the patients to neonatal BALB/c mice. The disease of the patients was reproduced clinically, histologically, and immunologically in these animals. Only IgG4 autoantibodies were detected by direct immunofluorescence, bound to the epidermis in the lesions of the mice, and by immunoelectron microscopy at the keratinocyte surface. IgG4 has previously been reported to be a blocking or protective antibody because it has poor effector functions in vitro, as compared with the other IgG subclasses. The finding that it is the pathogenic autoantibody in fogo selvagem raises the possibility that it may also be important in other autoimmune disease.
We examined the role of circulating autoantibodies in the pathogenesis of pemphigus vulgaris by p... more We examined the role of circulating autoantibodies in the pathogenesis of pemphigus vulgaris by passively transferring IgG fractions from five patients with pemphigus vulgaris into neonatal Balb/c mice, in doses of 1.5 to 16 mg per gram of body weight per day. Cutaneous blisters and erosions with the histologic, ultrastructural, and immunofluorescence features of pemphigus occurred in 39 to 55 mice given intraperitoneal injections of IgG from patients with pemphigus and in none of 58 control mice given normal human IgG. IgG fractions with high titers of pemphigus antibodies were most effective in inducing disease, and this effect was dose dependent. Titers of circulating IgG in mouse serum closely correlated with the extent of disease induced (P less than 0.002). This study strongly supports the proposed role of pemphigus autoantibodies in the pathogenesis of pemphigus vulgaris in human beings and demonstrates that pemphigus can be passively transferred to laboratory animals.
Bullous pemphigoid (BP) is an autoimmune skin disease that is characterized by the presence of su... more Bullous pemphigoid (BP) is an autoimmune skin disease that is characterized by the presence of subepidermal blisters resulting from a disruption of the adhesive interactions between basal keratinocytes and the cutaneous basement membrane. Autoantibodies from patients suffering from this disorder recognize two epidermal antigens, BP180 and BP230, both of which have been localized to the hemidesmosome, a transmembrane structure of stratified, squamous epithelia that functions in cell-matrix adhesion. In the present study we report the primary structural analysis of BP180 based on the sequence of a series of overlapping cDNA clones encompassing 4,669 bases of the BP180 transcript. A polymerase chain reaction-based protocol was used to confirm the contiguity of the cDNA segments. This cloned portion of the BP180 transcript was found to contain one long open reading frame (ORF) 4.596 bases in length. This ORF encodes a polypeptide of 155,000 Daltons with an isoelectric point of 9.7. The carboxy-terminal half of BP180, a stretch of 916 amino acids, consists of 15 collagen domains of variable length (15 to 242 amino acids) that are separated from one another by short stretches of non-collagen sequences. Located 76 amino acids upstream of the collagenous region is a putative transmembrane domain, a structural feature that distinguishes BP180 from all of the well-characterized members of the collagen family. This membrane-spanning domain is predicted to function as a signal-anchor sequence, directing the C-terminal collagenous segment of this protein to the exterior of the cell. The putative intracellular domain is highly basic with an isoelectric point of 10.37. This molecular analysis predicts that the BP180 antigen is an integral membrane protein of the hemidesmosome that contains a long extracellular collagenous tail. This combination of structural features suggests that BP180 may function as a cell-matrix adhesion molecule, with the collagenous region acting as a potential site of interaction with basement membrane components. Autoantibody-mediated disruption of such an adhesive interaction may play a critical role in the development of sub-epidermal blisters in BP patients.
Endemic pemphigus foliaceus, or fogo selvagem, is an autoimmune blistering skin disease caused by... more Endemic pemphigus foliaceus, or fogo selvagem, is an autoimmune blistering skin disease caused by IgG autoantibodies to a desmosome-associated glycoprotein. We studied the IgG subclasses with autoantibody activity in serum from 29 patients with active disease and in the skin lesions of 18 patients by immunofluorescence, using IgG-subclass-specific monoclonal antibodies. The predominant disease autoantibodies present in all patients were of the IgG4 subclass. IgG1 and IgG2 autoantibodies were detected in low titer in the 29 patients: IgG1 in 23 patients and IgG2 in 9. IgG3 autoantibodies were not detected in the serum of any patient. Direct immunofluorescence testing of skin lesions showed a preferential deposition of IgG4 on the keratinocyte surface. The pathogenic effect of IgG4 was demonstrated by the passive transfer of fractions containing IgG4 autoantibodies from the patients to neonatal BALB/c mice. The disease of the patients was reproduced clinically, histologically, and immunologically in these animals. Only IgG4 autoantibodies were detected by direct immunofluorescence, bound to the epidermis in the lesions of the mice, and by immunoelectron microscopy at the keratinocyte surface. IgG4 has previously been reported to be a blocking or protective antibody because it has poor effector functions in vitro, as compared with the other IgG subclasses. The finding that it is the pathogenic autoantibody in fogo selvagem raises the possibility that it may also be important in other autoimmune disease.
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Papers by Luis Díaz