ACTIVATION OF CD4-SPECIFIC T-CELLS BY MACROPHAGES INFECTED WITH LIVE TRYPANOSOMA-CRUZI AMASTIGOTES( AND CD8+ PARASITE)

T. cruzi-infected macrophages are potential candidates for the present ation of parasite antigens to T. cruzi-specific T lymphocytes. To asse ss this question, we examine the ability of peritoneal exudate macroph ages to process exogenous live or dead parasites and to activate defin ed populations of T. cruzi-specific immune T-cells. Macrophages infect ed with live amastigotes activated both lymph node CD4 + and spleen CD 8 + T-primed cells that proliferated and secreted cytokines. Lymph nod e CD4 + T-cells produced IFN-gamma and IL-10 while CD8 + T-cells produ ced IFN-gamma. In contrast, macrophages pulsed with dead parasites act ivated 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 recognit ion of infected macrophages. Taken together, these results demonstrate d that amastigote infected macrophages present parasite peptides assoc iated with MHC I and II molecules, activating both CD4 + and CD8 + T-c ells. Furthermore, the development of T. cruzi-specific CD8 + T-cells in vivo using the immunization protocol with non-living parasites as d escribed in this report could be explored for further studies on the r ole of CTL in the outcome of infection. (C) 1998 Elsevier Science B.V. All rights reserved.