BACKGROUND: Leprosy, a disease caused by Mycobacterium leprae, manifests itself into two clinical forms: the paucibacillary form is benign, Mitsuda positive and immunocompetent; the multibacillary form is severe, Mitsuda negative and immunodeficient. Multibacillary affected individuals, who release bacilli, are postulated to maintain endemic leprosy. OBJECTIVES: The authors used cultivated mycobacteria to test Mitsuda negative patients, with the objective to induce immune conversion. METHODS:A Mitsuda-like antigen was prepared from cultivated mycobacteria and tested in 28 Mitsuda negative leprosy patients. All patients were evaluated and then submitted to a new Mitsuda test. A control group of 28 Mitsuda negative leprosy individuals were inoculated with placebo and later evaluated by a second Mitsuda test. RESULTS: Patients inoculated with the experimental Mitsuda antigen had favorable responses: 25 presented positive macroscopic reactions and four were tuberculoid granuloma. When submitted to a second Mitsuda test, four individuals presented typical positive Mitsuda reactions, with tuberculoid granuloma. Among the control group inoculated with placebo, the responses were negative, and there was one positive response observed for the second Mitsuda test. CONCLUSIONS: In Mitsuda negative leprosy patients tested with an experimental Mitsuda antigen, we observed 14.29% of favorable responses, with Mitsuda-like reactions induced by the experimental Mitsuda antigen. When tested again with the Mitsuda antigen, we observed 14.81% of favorable responses with positive reactions.
Mitsuda antigen; Leprosy; Cellular immunity
