Naive, Ly6C−Sca-1− CD8+ and T cells were sort purified and cultured in the presence or absence of α-CD3/28, in the presence or absence of IL-27. After an 85-h culture, cells were analyzed for expression of PD-L1, PD-1, LAG-3, and CTLA-4. Representative FACS plots (left). Bar charts (right) show combined results from four independent experiments. Error bars indicate SEM. Statistical significance was determined by using Student t test. ns; p > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001.