Dermatitis herpetiformis: selective deposition of immunoglobulin A1 in granular deposits in clinically normal skin.

The subclass composition of IgA in granular deposits in the papillary dermis of clinically normal skin taken from 12 patients with dermatitis herpetiformis (DH) was determined using monoclonal IgA-subclass specific antibodies and immunofluorescence microscopy. In skin from one patient with extensive deposits of IgA minute amounts of IgA2 could be detected whereas IgA1 was found in all the biopsies examined. These findings favour the postulation that properties of certain IgA-molecules other than their antigen-binding specificity may cause their deposition in DH.