Human american cutaneous leishmaniasis (Leishmania b. braziliensis) in Brazil: lymphoproliferative responses and influence of therapy.

The host defence to Leishmania parasites is believed to depend on cell-mediated immune responses. Three groups of inhabitants from an endemic area in Rio de Janeiro were studied: Group I consisted of 28 patients with cutaneous lesions, Group II of 28 healthy persons (without ulcers) but with positive Montenegro skin tests (MST) and Group III of 29 healthy persons with negative MST. The peripheral blood lymphocyte proliferative responses induced by leishmanial-antigens (Leishmania b. braziliensis lymphoproliferative response) as well as by Concanavalin A (Con A-lymphoproliferative response), both measured by 3H-thymidine incorporation were tested in each group. The results showed that: The Leishmania b. braziliensis lymphoproliferative response (L.b.b.-LPR) in healthy persons with positive MST (Group II) was higher than in patients prior to therapy (Group I); A significantly higher L.b.b.-LPR was found in patients and healthy persons with positive MST as compared to Group III (negative MST); The L.b.b.-LPR of Group I (patients) increased during antimonial therapy--this might possibly be related to the destruction of parasites; The levels of L.b.b.-LPR after therapy became similar to the ones before therapy; All individuals from the three groups had a positive Con A-lymphoproliferative response (Con A-LPR); All patients who had a histopathological picture of granulomatous reaction also had a positive L.b.b.-LPR; A poor response to antimonial therapy observed in six patients was associated with a low L.b.b.-LPR.