p110δ inhibition blocks recall responses. PBMCs from healthy donors were stimulated with tetanus toxin in the presence of DMSO alone or IC. After 7 days, proliferation (A), IFN-γ (B), TNF-α (C), and IL-17 (D) production were measured. Each dot represents an individual donor. To calculate P values, 1-way repeated-measures analysis of variance was used to compare DMSO alone with IC. *.01 < P < .05; **.001 < P < .01; ***P < .001. Percentage inhibition was calculated for each donor to determine the range of sensitivity in the population, and median values are shown below the graph.