Suppression of JAK3; concentration and time dependent studies with dbcAMP. (A) Primed T cells were cultured for 24 hours with various concentrations of dbcAMP before Western blotting. (B) Primed T cells were cultured with 1 mmol/L dbcAMP for various lengths of time before Western blotting. An analysis of all experiments showed a significant reduction in JAK3 levels for both naive T cells (n = 5,P < .001) and for primed T cells (n = 8, P < .001) cocultured with dbcAMP.