MOLECULAR OVERLAP OF THE IGA TARGET ANTIGENS IN THE SUBEPIDERMAL BLISTERING DISEASES

Linear ISA disease (LAD) has circulating IgA auto-antibodies which hav e been found to be associated with epidermal- and dermal-derived antig ens. The localization and molecular weight(s) of the ISA target antige n(s) implicated in LAD and their relationship to the target antigens f or the IgA antibodies in bullous pemphigoid (BP) and cicatricial pemph igoid (CP) are unknown. Sera from patients with all 3 diseases who had circulating ISA antibodies were studied by immunoblotting with both e pidermal and dermal extracts. Our findings indicate that there is hete rogeneity in the localization and molecular weights of the target anti gen(s), with multiple bands demonstrated with some sera. Three princip al target antigens were identified with molecular weights of 110-120, 160-180 and one approximately 285 kD. These antigens were common to al l 3 diseases and were found in 25 patients. These results suggest that the target antigens for IgA basement membrane zone antibodies in LAD, BP and CP are multiple, complex in composition and may differ from th e conventional BP antigens.