Interferon-gamma and interleukin-4 production by human T cells recognizing Leishmania donovani antigens separated by SDS-PAGE.

Crude preparations of Leishmania donovani proteins were separated by preparative SDS-polyacrylamide gel electrophoresis. Fractions of separated proteins were recovered by electroelution directly from the gel into separate chambers. The isolated protein fractions were tested for induction of proliferation and interferon-gamma (IFN-gamma) production in cultures of peripheral blood mononuclear cells (PBMC) from individuals who had recovered from visceral leishmaniasis caused by L. donovani. The release of interleukin-4 (IL-4) by PBMC stimulated with the isolated L. donovani antigen fractions was measured after treatment with phorbol-myristate-acetate and ionomycin. The cells proliferated in response to all protein fractions with molecular weights in the range < 12 kDa to 85 kDa. In general, IFN-gamma was secreted in response to stimulation with all the protein fractions, whereas IL-4 production was infrequently observed. The results show that T cells from individuals who have been cured of visceral leishmaniasis recognize and respond to a wide range of leishmanial antigens. There was no evidence of particular fractions constantly giving either IFN-gamma or IL-4-producing responses.