A_2A receptor activation of Tc1 and Tc2 cells increases intracellular cAMP after costimulation. Tc1 and Tc2 cells were harvested on day 5 of culture, and restimulated with 3/28 beads either in the absence (-) or presence (+) of CGS (10^-7 M). Intracellular cAMP was then measured, as described in “Materials and methods.” Results are mean and SEM of triplicate values.