Concurrence of autoantibodies to bullous pemphigoid antigens and desmoglein 3: analysis of pathogenic and nonpathogenic antibodies

Case of pemphigus with immunoglobulin G and A antibodies, binding to both the intercellular spaces and basement membrane zone

We report a case involving a 62-year-old woman with in vivo-bound immunoglobulin (Ig)G and IgA antibodies in both the intercellular space (ICS) and basement membrane zone (BMZ). Her clinical and histopathological features were identical with those of pemphigus vulgaris, while the immunopathological findings suggested IgG/IgA pemphigus. Direct immunofluorescence (IF) showed in vivo-bound IgG and IgA antibodies in the ICS and BMZ, whereas indirect IF showed circulating IgG but not IgA antibodies in the ICS and BMZ. The anti-ICS IgG bound to desmoglein-3, while the anti-BMZ antibodies bound to the epidermal side of 1 mol/L NaCl-split skin. To the best of our knowledge, only two similar cases have been reported so far. Furthermore, we also examined IgG subclass distribution of the in vivo-bound and circulating anti-ICS and BMZ antibodies, and found that IgG1, IgG2 and IgG4 bound to ICS of the lesional skins, while IgG1 and IgG3 bound to the BMZ. The circulating anti-ICS antibodies belonged to IgG1 and IgG4, while the circulating anti-BMZ antibodies to IgG1, IgG2 and IgG4. We report a case involving a 62-year-old woman with in vivo-bound immunoglobulin (Ig)G and IgA antibodies in both the intercellular space (ICS) and basement membrane zone (BMZ). Her clinical and histopathological features were identical with those of pemphigus vulgaris, while the immunopathological findings suggested IgG/IgA pemphigus. Direct immunofluorescence (IF) showed in vivo-bound IgG and IgA antibodies in the ICS and BMZ, whereas indirect IF showed circulating IgG but not IgA antibodies in the ICS and BMZ. The anti-ICS IgG bound to desmoglein-3, while the anti-BMZ antibodies bound to the epidermal side of 1 mol/L NaCl-split skin. To the best of our knowledge, only two similar cases have been reported so far. Furthermore, we also examined IgG subclass distribution of the in vivo-bound and circulating anti-ICS and BMZ antibodies, and found that IgG1, IgG2 and IgG4 bound to ICS of the lesional skins, while IgG1 and IgG3 bound to the BMZ. The circulating anti-ICS antibodies belonged to IgG1 and IgG4, while the circulating anti-BMZ antibodies to IgG1, IgG2 and IgG4.