A_2AR engagement during activation promotes T cell tolerance. (A,B) Proliferation on rechallenge of A.E7 T cells after 4-day incubation without (A) or with (B) peptide in the absence (□) or presence (♦) of 1 μM CGS. (C) IFN-γ production on rechallenge of A.E7 T cells after priming without or with peptide (left or right side, respectively) in the absence () or presence () of 1 μM CGS. (D,E) Proliferation and IFN-γ production on rechallenge of A.E7s incubated with peptide and exogenous IL-2 in the absence or presence of 1 μM CGS. All rechallenges are done in the absence of CGS or exogenous IL-2. Data are representative of at least 3 independent experiments (*P < .05).