Epidermal class II human lymphocyte antigen expression in atopic dermatitis: a comparison with experimental allergic contact dermatitis.

Epidermal patterns of class II human lymphocyte antigen (HLA) expression in atopic and allergic contact dermatitis have been compared, using monoclonal antibodies recognizing each subregion. Expression of class II human lymphocyte antigens on keratinocytes has been confirmed in allergic contact dermatitis, while we have found them to be absent in atopic dermatitis. This finding argues that cell-mediated immune responses, possibly to epicutaneous contact with allergen, are not implicated in the pathogenesis of atopic dermatitis.