Cytokine responses in leprosy lesions.

The clinical spectrum of leprosy reflects the diverse nature of human immune responses to Mycobacterium leprae. The clinical presentations correlate with the level of cell-mediated immunity against M. leprae. Cell-mediated immunity, as assessed by the Mitsuda reaction, is positive in tuberculoid patients and negative in lepromatous patients. In contrast, humoral immunity, as assessed by anti-M. leprae antibodies is greatest in lepromatous patients. The inverse correlation between cell-mediated immunity can be explained on the basis of the local cytokine pattern.