Monoclonal antibodies cross-reactive with group A streptococci and normal and psoriatic human skin

Infection with group A streptococci has been implicated as a factor capable of exacerbating psoriasis. In order to explore the possibility of cross-reactivity between streptococcal antigens and human skin in this phenomenon, skin from psoriatic patients and control subjects was reacted with 3 monoclonal antibodies against group A streptococci and antibody binding was estimated by the indirect immunofluorescence technique. Monoclonal antibody 54.2.8 stained the nuclei and cytoplasm of cells within the epidermis and epidermal appendages, as well as cells scattered throughout the dermis. In contrast, monoclonal antibodies 49.8.2 and 36.2.2 labeled the cytoplasm of epidermal cells and epidermal appendages but did not react with nuclei. No difference in the staining patterns of control skin and uninvolved skin from patients with psoriasis was observed. However, skin from psoriatic lesions contained large amounts of cross-reactive skin component(s). Sera from patients with guttate psoriasis did not react differently with normal or psoriatic skin when compared with normal sera. Western immunoblots of skin extracts demonstrated that monoclonal antibody 54.2.8 reacted with a family of proteins in the molecular weight range of 60-70K. The results indicate that component(s) in human skin share cross-reactive epitopes with group A streptococci. Immunologic cross-reactions between group A streptococci and human skin may play an important role in the exacerbation of certain skin disorders following streptococcal infections.