The cytotoxic response to murine cytomegalovirus. II. In vitro requirements for generation of cytotoxic T cells

Murine cytomegalovirus (MCMV)-immune lymph node (LN) cells were generated following 4 days culture of draining popliteal LN cells removed after bilateral hind footpad inoculation of mice with 4 × 10 2 p.f.u. MCMV. This cell population expressed both cytotoxic activity against MCMV-infected mouse embryo fibroblasts (MEF) and the capacity to release lymphokine upon stimulation with MCMV-infected MEF. Cytotoxicity and lymphokine release were Class I, H-2-restricted, virus-specific and dependent upon Thyl. 2 +, Lyt2 + cells. Mixing of 5 x 10 s MCMV-immune T cells with an excess of syngeneic MCMV-infected MEF stimulators produced etectable vels of the lymphokine interleukin-3 by 1 h, with a maximum rate of its release between 1and 6 h and plateau levels by 14 h. The capacity to stimulate virus-specific MCMV-immune T cells was acquired by MEF at 1 h after MCMV infection with maximum stimulator ability attained by 8 h. In the presence of a fixed number of MCMV-immune T cells, and titration to excess of syngeneic 3 h or 18 h MCMV-infected MEF, lower interleukin-3 plateau levels were obtained with 3 h than with 18 h MCMV-infected stimulators. This suggested that fewer T cells responded to 3 h than to 18 h MCMV-infected MEF