Studies of autoantigens recognized by IgA anti-keratinocyte cell surface antibodies

We have examined autoantigens for IgA anti-keratinocyte cell surface antibodies 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 formation throughout the epidermis and IgA antibodies reactive with the entire: 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 analysis 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 that IgG antibodies in one G/A case each recognized one of the two antigens. With immunoblotting of desmosome enriched fraction obtained from bovine snout epidermis, IgA antibodies in 10 IAVPD and 3 G:A cases and IgG antibodies in 4 G/A cases showed reactivity with either desmoglein 1 or desmocollin, another desmosomal cadherin. These results indicate that IAVPD and G/A cases are heterogeneous in terms of both clinical features and antigens and that the IgA autoantibodies in these cases may react with different antigens from those for I G autoantibodies.