Detection of a herpes simplex viral antigen in skin lesions of erythema multiforme

The commonest variety of erythema multiforme follows a lesion caused by a recurrent herpes simplex virus infection. In studying the immunopathogenesis of herpes-associated erythema multiforme, we examined skin lesions for the presence of a herpes simplex viral antigen by an indirect immunofluorescence test using a monoclonal antibody to a major type-common glycoprotein antigen, gB. Focal staining showed this antigen to be present in epidermal cells in 12 of 16 skin biopsy specimens. The staining was similar to, but less intense than, that seen in biopsy samples of lesions of recurrent herpes simplex virus infections. Similar findings were not seen in control skin biopsy specimens from lesions of other skin diseases; a control monoclonal stain also was negative in biopsy specimens. These findings suggest that the immune reaction and subsequent tissue damage of herpes-associated erythema multiforme are due to the presence of herpes antigens in the skin.