Studies with pharmacologic inhibitors and antigens. (A) Comparable sensitivity of cytokine release induced by OKT3 and TGN1412 to corticosteroid-mediated suppression. High-density precultured cells were prepared and stimulated as described in Figure 1B. Dexamethasone (Dex) was included at the final concentrations given, and cytokines were measured after 24 hours. (B) Fresh or precultured PBMCs (prepared as in Figure 1) were stimulated with a suboptimal concentration of OKT3 (0.01 μg/mL) in the presence of titrated amounts of PP1 as given. [³H]Thymidine incorporation was assessed between day 2 and 3. (C-E) Comparison of fresh and precultured PBMCs cultured as in Figure 1A and B. (C) Response to the bacterial superantigen SEB. (D) Overview over tetanus/diphtheria toxoid (Td) recall responses of 6 random donors tested either fresh or after 2-day high-density preculture. (E) Dose-response to Td of the strongest responder shown in panel D (blue line). Wilcoxon signed rank test: *P ≤ .05. Data are mean ± SD for triplicate samples.