A. In complete HL-1 medium, CD4+ T cells (1×105 cells/well) were activated with plate bound anti-CD3 (1 μg/ml) and soluble anti-CD28 (1 μg/ml) for 48 h in the presence of either 50 μM PKA inhibitor 8-bromoadenosine 3', 5'-cyclic monophosphorothioate, Rp-isomer or medium alone. Cells were co-cultured with ManLAM (10 μg/ml) or medium alone. Following incubation, supernatants were harvested for IL-2 measurement. Data points are expressed as means of triplicate samples +/−S.D. Results are representative of four independent experiments. B. CD4+ T cells (3×106 cells) were pre-incubated with ManLAM (10 μg/ml) or medium alone for 1 h at 37°C, and stimulated as in Fig. 3. Western analysis was performed with antibody to phosphorylated Lck-Tyr505 (upper panel) or total Lck (lower panel). Results are representative of at least three independent experiments.