Trypanosoma cruzi suppresses the ability of activated human lymphocytes to enter the cell cycle.

Using an in vitro system in which human peripheral blood mononuclear cells stimulated with the T-lymphocyte mitogen phytohemagglutinin were cocultured with Trypanosoma cruzi trypomastigotes, we demonstrated a marked accumulation of cells in G0/G1a during the 72-hr observation period whereas mitogen-stimulated cells in parallel cultures lacking the parasite readily entered the G1b, S, and G2/M phases. These results suggest that the immunological alterations that occur in acute Chagas' disease may result from an early cell cycle blockade induced by the parasite.