Detection of IgA autoantibodies to desmogleins by an enzyme-linked immunosorbent assay: the presence of new minor subtypes of IgA pemphigus.

OBJECTIVE To examine the frequency of antidesmoglein 1 (Dsg1) and antidesmoglein 3 (Dsg3) IgA autoantibodies in IgA pemphigus. DESIGN We developed an enzyme-linked immunosorbent assay against recombinant Dsg1 and Dsg3 to detect IgA autoantibodies. PATIENTS Twenty-two patients with IgA pemphigus were studied. Among them, 10 patients had subcorneal pustular dermatosis type, 9 patients had intraepidermal neutrophilic IgA dermatosis type, and 3 patients had pemphigus foliaceus-like clinical features. RESULTS Of the 22 cases of IgA pemphigus, 3 cases were positive for anti-Dsg1 IgA antibodies and only 1 case was positive for anti-Dsg3 IgA antibodies. In those 4 cases, there were no IgA autoantibodies against other components of the keratinocyte cell surfaces because preincubation with the respective recombinant desmogleins removed the immunoreactivity on immunofluorescence. All 10 patients with subcorneal pustular dermatosis type IgA pemphigus were positive against desmocollin 1 expressed on COS-7 cells. No target antigen was detected in the other 8 cases. CONCLUSIONS Desmogleins were recognized by IgA antibodies of a few patients with IgA pemphigus. Considering that subcorneal pustular dermatosis type IgA pemphigus recognizes desmocollin 1, autoimmune targets of IgA pemphigus are more heterogeneous than previously considered.