ADOR expression on B cells and signaling in the presence of ADOR agonists or antagonists. (A) RT-PCR results are shown for relative expression of A₁R, A_2AR, A_2BR, and A₃R. RT-PCR was performed as described in Methods and materials using the indicated subsets of T cells and B cells. No message for A_2BR was detected in T or B lymphocytes. The data are from 1 representative experiment of 3 performed with cells of different normal donors. (B) Effects of ADOR antagonists or ADOR agonists (all used at 1 μM after initial titrations) on proliferation of B cells cultured in the presence of IL-4, CD40L, and CADO are shown. (C) Effects of ADOR agonists on proliferation of B cells cultured in the presence of IL-4 and CD40L. The viability of B cells incubated with agonists or antagonists was always >95%. Data in B and C are means ± SD from 3 independent experiments with cells of different normal donors.