[Cell mediated immune response in leprosy lesions].

Five biopsies from 2 leprosy patients, tuberculoid (TT), and polar lepromatous (LLp), were studies using immunoperoxidase procedures with monoclonal antibodies. Immunohistochemical patterns of them were remarkably different. In a TT patient, epithelioid cells and helper/inducer T (Leu 3a+) cells made the central core of a granuloma surrounded by suppressor/cytotoxic T (T8+) cells and B cells, indicating a possible immune-mediated cell response. The distribution of B cells suggests that not only T but also B cells may take part in the formation of the granuloma. In contrast, helper/inducer cells, suppressor/cytotoxic cells, and macrophages of a LLp patient were admixed uniformly at the site of the lesion, indicating a poor immune response. Although the ENL skin lesion of this LLp patient did not eliminate the bacilli, HLA-DR expression by keratinocytes and increased numbers of helper/inducer cells found in an ENL lesion, comparable to the findings of TT leprosy, suggests that a cell mediated immune response may play some role in the pathogenesis of ENL reaction.