Figure 4.

Selective inhibition of Teff cell proliferation by PDE4 inhibition in vitro. Proliferation of purified CD4⁺CD25⁻ Teff cells exposed to PDE inhibitors. Teff cells (5 × 104/well) were cultured with immobilized anti-CD3 mAb or control in the presence of IBMX (300 μM), DP (100 μM), PICL, PF-04957325 alone or in combination, or vehicle control (0.1% DMSO). The extent of proliferation was determined by [³H]thymidine incorporation at 64 h and results are presented as mean + SEM counts per min (cpm). Data are representative of three to five independent experiments performed in triplicate (^*p < 0.05, ^**p < 0.001, comparisons to vehicle were analyzed using a one-way ANOVA and Bonferroni t-test).