Rolipram enhances the suppressive capacities of T_reg cells in vitro.

(A, B) BALB/c splenic DC (3×10⁴ per well) were cocultured with allogeneic C57BL/6 Thy1.2⁺ T cells (1×10⁵ per well) with titrated amounts of the PDE4 inhibitor rolipram (100 to 1000 nM), PDE2 inhibitor BAY-60-7550 (100 to 1000 nM) or PDE3 inhibitor Cilostazol (1 µM to 10 µM) for 3 days. Cell proliferation was determined after 3 days by ³H-thymidine incorporation. (B) DC (3×10⁴ per well) were cocultured with allogeneic C57BL/6 Thy1.2⁺ T cells (1×10⁵ per well) as in (A), but C57BL/6 T_reg cells (3×10⁴ per well) were added. (C) DC (3×10⁴ per well) were cocultured with allogeneic C57BL/6 Thy1.2⁺ T cells (1×10⁵ per well) and C57BL/6 T_reg cells in indicated ratios for 3 days. Where indicated PDE4 inhibitor rolipram (100 nM), PDE2 inhibitor BAY-60-7550 (300 nM) or PDE3 inhibitor (3 µM) was added and proliferation was assessed after 3 days by ³H-thymidine incorporation. All depicted results were assayed in triplicate wells and are representative of three independent experiments. (*) indicates significant differences by Mann-Whitney U-test; n.s. – no significant differences.