Immunohistologic comparison between armadillo-derived leprosin and standard lepromin skin tests in leprosy patients

A comparison was made on the in situ immunological characteristics of dermal infiltrates of early (24-hour) and late (3-4 weeks) skin reactions in leprosy patients. The skin reactions were induced by armadillo-derived leprosin coupled to liposomes and standard Dharmendra lepromin. Most lymphocytes in the early reaction induced by both antigens were positive for Leu 4, Leu 3a, OKT8 and Ia like antigens indicating thereby the presence of activated T cells. The ratio of Leu 3a/OKT8+ cells were similar. In the late reaction elicited by both antigens, the lymphocytes in the granulomas were predominantly activated T lymphocytes expressing Leu 4, Leu 3a, OKT8 and Ia like antigens. Leu 3a+ cells were scattered diffusely amidst the epithelioid cells. In contrast, the OKT8+ cells were present mainly as 'a ring' in the periphery of the granuloma. A similar ratio of Leu 3a+/OKT8+ cells was observed in these granulomas. Macrophages in the granulomas expressed Ia like antigens. These observations indicate that the immunological characteristics of dermal infiltrates in the skin reaction induced by armadillo-derived leprosin coupled to liposomes and standard Dharmendra lepromin appear to be identical.