Antiendomysial antibody--useful serological indicator of dermatitis herpetiformis

Antiendomysial antibodies (EmA) of the IgA class are directed against reticulin components of the primate smooth muscle and are markers of gluten-sensitive enteropathy. These antibodies occur in essentially all active cases of celiac disease and in about 70% of dermatitis herpetiformis (DH) patients. IgA deposits in the dermal papillae of the skin are the hallmark of DH and are employed routinely in establishing its diagnosis. The incidence of IgA deposits in skin varies depending upon the site and type of biopsy specimen taken. We studied sera and skin biopsy specimens for EmA and for IgA deposits in the skin from 11 DH patients. EmA were detected in the sera of 10 of the 11 cases. Of these 11 patients, 9 were positive for IgA deposits in their skin, as revealed by direct immunofluorescence (IF). The immune deposits were detected in the normal, and not in the lesional skin. DH cases that were initially negative on biopsy and serum positive for EmA were found to be positive when a repeat biopsy of the normal skin was performed. Thus, serological studies in conjunction with direct IF studies of the normal skin are useful in making a diagnosis of DH.