IFN-γ/IL-4–primed PCMCs express MHC class II and CD86 and induce functional responses in effector OT-II T cells but not in their naive counterparts. (A-C) PCMCs were incubated 72 hours with IFN-γ (50 ng/mL) or IL-4 (10 ng/mL) or with IFN-γ + IL-4. CD86 and I-A^b molecule expression (using the KH74 or M5/114 mAb) was analyzed by flow cytometry. The numbers inside the panels indicate the percentage of positive cells. Data are representative of at least 10 experiments. (D) APCs were pulsed or not for 16 hours with 10 μg/mL OVAp and cocultured with naive (left) or effector (right) OT-II T cells. OT-II T-cell activation was monitored by CD69 expression (after 20 hours of coculture), IFN-γ production (after 20 hours of coculture), and proliferation (after 72 hours of coculture). Results are presented as mean ± SEM of 4 independent experiments. nd indicates not detected.