INTERFERON-GAMMA (IFN-GAMMA) AND TUMOR-NECROSIS-FACTOR-ALPHA (TNF-ALPHA) ARE NECESSARY IN THE EARLY STAGES OF INDUCTION OF CD4 AND CD8 CYTOTOXIC T-CELLS BY MYCOBACTERIUM-LEPRAE HEAT-SHOCK-PROTEIN (HSP)65 KD

Cytotoxic T cells (CTL) may play an important role in host defence aga inst mycobacterial infections. CD4 CTL are preferentially induced by m ycobacteria, but both CD4 and CD8 CTL may be necessary components of a protective immune response. The 65-kD mycobacterium heat shock protei n (hsp65) is a poor inducer of CTL in multibacillary leprosy (MB) pati ents. In this study we evaluate the possible role of cytokines in modu lating the cytotoxic activity of CTL from leprosy patients and normal individuals (N) against autologous macrophages presenting Mycobacteriu m leprae hsp65. Our results show that hsp65-specific CTL were generate d from both CD4 and CD8 lymphocytes. In N, individual cytokines as wel l as the combination of them were able to modify the hsp65-induced cyt otoxic activity. The effect of cytokines on leprosy patients' lymphocy tes was different in MB and paucibacillary (PB) patients. Thus, IL-6, IL-2, IFN-gamma or TNF-alpha did not modify the generation of hsp65-CT L from either MB (with or without an erythema nodosum episode (ENL)) o r PB. In all the patients the simultaneous addition of two cytokines w as required in order to increase CTL generation. In MB, IL-6 plus IFN- gamma or IL-2 increased both CD4 and CD8 CTL, while TNF-alpha plus IFN -gamma up-regulated only CD4 CTL. In PB, CD8 CTL were prominent with I L-6 plus IFN-gamma, while the increase was significant in CD4 CTL with IL-6 plus IL-2. Down-regulation of CTL was observed by addition of IL -4, IL-10, anti-IFN-gamma or anti-TNF-alpha in N controls. Our data de monstrate that IFN-gamma and TNF-alpha must be present for at least th e first 60 h of the induction stage in order to generate full hsp65 CT L. Hence, IFN-gamma and TNF-alpha would be key factors in the generati on of hsp65 CTL.