A_2AR expression is up-regulated on T-cell activation and preferentially inhibits IL-2 production. (A) cAMP levels after CGS incubation of A.E7s previously mock stimulated (◇) or stimulated with anti-CD3 in the presence or absence of CSA (▵ or •, respectively). (B) cAMP levels of naive or previously activated primary T cells from A_2AR Wt or null mice after incubation with 0 or 1 μM CGS ( and , respectively, *P < 0.05). (C) IL-2 (top) and IFN-γ (bottom) production of A.E7 T cells during activation with increasing doses of CGS. ID₅₀ for IL-2 is 8 nM, and for IFN-γ 750 nM. (D) Proliferation of A.E7s with 0 or 1 μM of CGS. Data are representative of 3 separate experiments.