T lymphocyte subsets in the skin lesions of patients with leprosy.

Lymphocyte subsets in the tissues of fourteen patients with leprosy were studied using monoclonal antibodies and a modified immunoperoxidase technic. Two immunohistologic patterns were observed. In tuberculoid leprosy, helper-inducer cells were present among the aggregates of mononuclear phagocytes (epithelioid cells), but the suppressor-cytotoxic cells were predominantly in the lymphocytic mantle surrounding the epithelioid cell aggregates. In reversal reaction and lepromatous tissues, the helper-inducer and the suppressor-cytotoxic cells were both distributed among the mononuclear phagocytes (histiocytes). In tuberculoid specimens the Langerhans cells of the epidermis were increased in number as compared to lepromatous and normal tissues. The technic used appears to be of value in studying some of the cellular components of the immune response in situ.