[Monoclonal antibodies (BL7 and BL9) having crossed reactivity with cells of the human epidermis].

The relationships between epithelial cells and immunocompetent cells could be approached by studying of the common antigens expressed by these two cell types. This paper reports the study of two monoclonal antibodies (BL7 and BL9) which react with epidermal cells. BL7 was obtained after immunization of mice with human thymic cell suspensions and BL9, after immunization with Raji cells. BL7 stained the epithelial network of the thymus and the basal cell layer of the epidermis. BL7 also reacted with the endothelial cells of the vessels of the dermis. This reactivity against the basal cell layer of the epidermis was observed in man, mice and rabbit. BL9 showed a reactivity against thymic epithelial cells and stained the membrane of the keratinocytes of the human epidermis. The antigenic expression revealed by BL9 decreased during the epidermal cell differentiation and disappeared in the horny layer. BL9 showed no reactivity with the epidermis of mice and rabbit. These two monoclonal antibodies are new tools in cutaneous immunopathology: BL7 is the first monoclonal experimental marker which identifies the basal cells of the epidermis, BL9 identifies an antigen related to the human epidermal cell differentiation.