Concomitant occurrence of circulating IgA anti-intercellular and anti-basement membrane zone antibodies in autoimmune blistering diseases: immunofluorescence and immunoblot studies.

Recently, cases with circulating IgA anti-intercellular antibodies have been described. The objective of this study was to present immunofluorescence and immunoblot findings in three cases of bullous diseases with concomitant circulating IgA anti-intercellular and anti-basement membrane zone antibodies. Direct immunofluorescence, indirect immunofluorescence on intact and 1M NaCl-split skin, immunoblotting of epidermal extracts from dispase- and EDTA-separated (two different procedures) human skin, and immunoblotting of the bovine desmosome preparation were performed. All three cases had IgA anti-intercellular and anti-basement membrane zone antibodies. However, immunoblot results were divergent. Case 1 had antibodies against the 150 kD pemphigus foliaceus antigen (IgG), the 170 kD protein (IgG and IgA), and the 97 kD antigen (IgG and IgA). Case 2 had IgG antibodies reactive with the 230 kD and the 170 kD bullous pemphigoid antigens, while case 3 had IgA antibodies against the 97 kD antigen only. The results of immunofluorescence and immunoblot studies in our patients widen the spectrum of laboratory features in blistering skin diseases mediated, at least in part, by antibodies of the IgA class.