Figure 5.

Expression of activation markers after primary activation of Th cells, inhibited for cell cycling. CFSE-labeled, naive CD62L⁺CD4⁺ OVA-TCR^tg/tg cells were activated with OVA_323–339, APCs, IL-4, anti–IL-12, and anti–IFN-γ in the presence or absence of cell cycle inhibitors, as indicated. 1 d after priming, IL-4 and the antigen were removed and anti–IL-4, anti–IL-12, anti–IFN-γ, IL-2, and fresh inhibitors were added. On day 2 after onset of stimulation, live cells were analyzed for expression of CD25, CD44, CD62L, and CD69. Induction of IL-2 expression was determined by intracellular staining after PMA/ionomycin restimulation in the presence of the indicated inhibitors at that time point. The frequencies of positive cells were determined by gating on OVA-TCR⁺ cells.