IFN-GAMMA, IL-6 AND IL-4 MODULATE M-LEPRAE-SPECIFIC OR PPD-SPECIFIC CYTOTOXIC T-CELLS IN LEPROSY PATIENTS

Specific cytotoxic T cells against intracellular pathogens may be gene rated in vitro. On the other hand it is well known that cytokines can regulate almost every aspect of immune function. The aim of this study was to evaluate the effect of some cytokines on the generation of cyt otoxic T cells with specificity for Mycobacterium leprae- or PPD-pulse d autologous macrophages from leprosy patients and normal controls. Pe ripheral blood mononuclear cells from M. bovis BCG-immunized controls or from leprosy patients were stimulated with antigen, in the presence or absence of cytokines, for 7 days. These were used as effector cell s in a 4-h [Cr-51]-release assay. Our results show that development of cytotoxic T cells may be enhanced by gamma-IFN, IL-6 or the combinati on of IL-6 and IL-2. Addition of IL-2 or TNF-alpha alone did not modif y the generation of cytotoxic activity. IL-4 down-regulated the cytoto xic response and gamma-IFN was able to counteract this effect. Hence, the generation of specific cytotoxic T cells can be modulated by cytok ines. Whether this cytotoxic mechanism contributes to protection or ti ssue damage in M. leprae infection remains to be determined.