Blocking the effect of CTLA-4-Fc on human PBMCs by anti-B7 mAb. IDO (A) and IFN-γ (B) mRNA expression in human PBMCs after 12-hour incubation with CTLA-4-Fc or mAb anti-B7.1, anti-B7.2, or both anti-B7.1 and anti-B7.2. The last 3 bars on the right of each panel represent simultaneous treatment of PBMCs with CTLA-4-Fc and mAb anti-B7.1 and/or anti-B7.2. P values, indicated in the text, are based on 10 independent experiments. Mean values plus standard errors are shown.