Differential Interferon-γ Production Characterizes the Cytokine Responses to Leishmania and Mycobacterium leprae Antigens in Concomitant Mucocutaneous Leishmaniasis and Lepromatous Leprosy.

Background. Tegumentary leishmaniasis and leprosy display similar spectra of disease phenotypes, which are dependent on cell-mediated immunity to specific antigens. Diffuse cutaneous leishmaniasis and lepromatous leprosy represent the anergic end of the spectrum, whereas mucocutaneous leishmaniasis and tuberculoid leprosy are associated with marked antigen-specific cellular immune response. Methods. We characterized and compared the cell-mediated response to Leish mania and Mycobacterium leprae antigens in a patient with an intriguing association of mucocutaneous leishmaniasis with lepromatous leprosy, which are at opposite ends of the immunopathological spectra of these diseases. This was done by performance of skin tests and by assessment of the cell proliferation and cytokine production of peripheral blood mononuclear cells (PBMCs). Results. Strong skin-test reactions and PBMC proliferation were observed in response to Leish mania antigens but not to M. leprae antigens. The stimulation of PBMCs with Leish mania and M. leprae antigens induced comparable levels of tumor necrosis factor-α, interleukin-5, and interleukin-10. However, the interferon-γ response to Leishmanici antigens was remarkably high, and that to M. leprae antigens was almost nil. Conclusions. We found that concomitant leprosy and tegumentary leishmaniasis can produce opposite polar forms associated, respectively, with absent or exaggerated cell-mediated immune responses to each pathogen. This suggests that independent mechanisms influence the clinical outcome of each infection. Moreover, interferon-γ appears to play a major role in the clinical expression of these intracellular infections. [ABSTRACT FROM AUTHOR]