Figure 6.In vitro response of human PBMC to antagonist anti-CD28 mAbs and ADA. Human PBMC were stimulated with anti-CD3 antibodies and different types of anti-CD28 mAbs plus indicated concentrations of IgG containing ADA. (A) Proliferation at 72 h and cytokine release at 48 h in the presence of excipient, FR104 (10µg/ml), divalent agonist anti-CD28.3 mAbs (10 µg/ml), superagonist anti-CD28 ANC28.1 mAbs (10µg/ml), ADA-negative purified IgG (1.3 mg/ml), or ADA-positive purified IgG from two different baboons (1.3 mg/ml).(B) Same experiments as in (A) where human PBMC were cultured with 10 µg/ml of FR104 and increasing concentrations of ADA-negative or ADA-positive purified IgG (ranging from 0 to 1300 µg/ml as indicated in the upper panel).Data are means ± SEM of 3 different human blood donors. LLOQ: Lower limit of quantification.