Mice received transplants as described in “Materials and methods.” After 7 days, splenic CD4⁺ T cells were purified by magnetic separation or FACS and stimulated in culture by plate-bound antibodies to CD3 and CD28 (both at 10 μg/mL) or alloantigen (irradiated B6D2F1 peritoneal macrophages). Ex vivo responses to alloantigen were determined in MLC. Results represent mean ± SE of triplicate wells and one of 3 similar experiments.

P < .05 versus control T cells. Proliferative responses (×10³) were measured by ³H incorporation. Stimulation index (SI) is the proliferation to alloantigen/unstimulated cultures. IFNγ (U/mL), IL-4 (pg/mL), and IL-10 (pg/mL) were determined in culture supernatants by ELISA. IL-4 (pg/mL) and IL-10 (pg/mL) were at or below the level of detection in MLC cultures and no cytokines were detectable from unstimulated cultures. Cytotoxicity is presented as lytic units (1000/the effector-to-target ratio at which 10% and 20% specific lysis was recorded). Lysis to donor-type targets was less than 2%. Data presented are one of 3 experiments in which consistent differences in cytotoxicity could not be demonstrated between groups.