STUDIES OF AUTOANTIGENS RECOGNIZED BY IGA ANTI-KERATINOCYTE CELL-SURFACE ANTIBODIES

We have examined autoantigens for IgA anti-keratinocyte cell surface a ntibodies in 17 intercellular IgA vesiculopustular dermatosis (IAVPD) cases showing only IgA antibodies and 5 cases showing both IgG and IgA antibodies (GA cases). IAVPD cases were divided into two subtypes: (1 ) intraepidermal neutrophilic IgA dermatosis type showing pustule form ation throughout the epidermis and IgA antibodies reactive with the en tire: epidermis and (2) subcorneal pustular dermatosis type containing IEA antibodies reactive with the uppermost portion of the epidermis. Most G/A cases showed atypical clinical features. With immunoblot anal ysis of normal human epidermal extracts: IgA antibodies in these cases showed no specific reactivity with either pemphigus foliaceus antigen (desmoglein 1) or pemphigus vulgaris antigen (desmoglein 3), except t hat IgG antibodies in one G/A case each recognized one of the two anti gens. With immunoblotting of desmosome enriched fraction obtained from bovine snout epidermis, IgA antibodies in 10 IAVPD and 3 G:A cases an d IgG antibodies in 4 G/A cases showed reactivity with either desmogle in 1 or desmocollin, another desmosomal cadherin. These results indica te that IAVPD and G/A cases are heterogeneous in terms of both clinica l features and antigens and that the IgA autoantibodies in these cases may react with different antigens from those for I G autoantibodies.