Autoimmune Skin Diseases

Bullous autoimmune skin diseases, characterized by the formation of bullae or vesicles, are divided into two groups dependent on the location of clefts and the formation of bullae within the skin. In the pemphigus group of diseases the vesicles form intradermally; in pemphigoid the clefts occur at the dermal epidermal junction. The primary lesion of pemphigus is acantholysis in which the epidermal cells loose their adhesion, separate from one another and become rounded. The loss of cellular adhesion is due to autoantibody directed to one or more of the cell adhesion proteins, particularly the desmosomal antigens of the keratinocytes of stratified squamous epithelium. Marked heterogeneity of desmosomal antigens of squamous epithelium occurs dependent on the degree of maturation and differentiation of the keratinocytes within the epithelium. In vitro studies of cultured keratinocytes have shown differences in antigenic expression dependent on culture conditions. Thus antigen expression in vivo, may also depend on the location and function of squamous epithelium in different areas of the body. 1,2