GPR54 promotes CD8+ T cell exhaustion in vitro. Gpr54
+/+ and Gpr54
−/− mouse splenic CD8+ T cells activated with α‐CD3 (5 µg)/α‐CD28 (2 µg) for 72 h, proliferation A) measured by CFSE, B) degranulation detected with CD107a and PMA/ionomycin plus protein transport inhibitor for 3 h. CD8+ T cell with PMA/ionomycin plus protein transport inhibitor for 4 h, C) TNFα and D) IFNγ release detected by FCM. CD8+ T cell with ionomycin for 16 h, then α‐CD3/α‐CD28 for 24 h, E) TNFα and F) IFNγ release (n = 6) measured by FCM. CD8+ T cell with ionomycin for 16 h, then G) FCM detection PD‐1 and H) LAG‐3 expression levels (n = 6). All data are from at least three independent experiments. Data are represented as the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001 by unpaired Student's t‐test (A–D) or one‐way ANOVA followed by LSD analysis (E–H).