FIG. 5.

Nonimmune CD4⁺ and CD8⁺ T lymphocytes proliferate in response to T. gondii and Ag-presenting cells. T lymphocytes from normal C57BL/6 mice (purified by passage over anti-mouse Ig columns) were subjected to treatment with rabbit complement and anti-CD4 MAb (to obtain CD8⁺ T cells) or anti-CD8 MAb (to obtain CD4⁺ T cells). The resulting populations were cultured with irradiated splenic adherent cells (SAC) that were either untreated, preincubated with T. gondii soluble Ag extract, or preinfected with RH strain tachyzoites. For some CD8⁺ populations, recombinant murine IL-2 was included. Proliferation was measured by incorporation of [³H]thymidine (3H-TdR), added 72 h after culture initiation.