Activation of CD4+ and CD8+ parasite-specific T-cells by macrophages infected with live T-cruzi amastigotes

T. cruzi-infected macrophages are potential candidates for the presentation of parasite antigens to T. cruzi-specific T lymphocytes. To assess this question, we examine the ability of peritoneal exudate macrophages to process exogenous live or dead parasites and to activate defined populations of T. cruzi-specific immune T-cells. Macrophages infected with live amastigotes activated both lymph node CD4 + and spleen CD8 + T-primed cells that proliferated and secreted cytokines. Lymph node CD4 + T-cells produced IFN-gamma and IL-10 while CD8 + T-cells produced IFN-gamma. In contrast, macrophages pulsed with dead parasites activated only lymph node CD4 + T-cells, which proliferated and secreted IFN-gamma. Interestingly, the immunization with heat-killed parasites primed mice for CD8 + T-cells which were expanded in vitro by recognition of infected macrophages. Taken together, these results demonstrated that amastigote infected macrophages present parasite peptides associated with MHC I and II molecules, activating both CD4 + and CD8 + T-cells. Furthermore, the development of T. cruzi-specific CD8 + T-cells in vivo using the immunization protocol with non-living parasites as described in this report could be explored for further studies on the role of CTL in the outcome of infection. (C) 1998 Elsevier Science B.V. All rights reserved.