Proliferative response of human T cells to stimulation with Leishmania infantum and L. major promastigotes in logarithmic and stationary growth phase

T cells from healthy donors, non-exposed to Leishmania, proliferative and produce lymphokines when cultured in the presence of killed Leishmania promastigotes. We compared the stimulative activity of L. major and L. infantum promastigotes harvested in logarithmic and stationary growth phase on human T cells by performing a proliferation kinetics during the first 5 days of culture. Stationary-phase promastigotes induced a good response at the 4th-5th day, whereas the effect of logarithmic-phase promastigotes was almost undetectable. Both species gave a similar pattern. The implications of these findings in the current model of immunologic reaction to leishmaniasis are discussed.