Immunological profile of treated lepromatous leprosy patients.

The immune responses of 19 treated lepromatous patients who had remained smear negative for a long period were assessed for specific cell-mediated immunity (CMI), anti-Mycobacterium leprae antibodies and cytokine release in response to challenge with M. leprae soluble antigen (MLSA). All of these patients remained anergic to Mitsuda lepromin. Lymphoproliferation in response to M. leprae antigen was noted in only two patients. Significant reduction in the phenolic glycolipid I (PGL-I) antibody response in treated patients with no difference in the M. leprae 35-kDa antibody response was observed when these responses were compared with those of active lepromatous patients. More treated patients produced interleukin-2 (IL-2) and interferon gamma (IFN-gamma) than did active patients. On the other hand, fewer treated patients produced IL-10 than did active patients. These limited findings suggest that the host immune response makes an attempt toward upregulation of CMI in some treated LL/BL patients.