Figure 4. Reduced T_H1 differentiation of transferred IRF4^−/− OT-II T cells.

Purified CD4⁺ T cells from WT CD90.1⁺CD90.2⁺ or IRF4^−/− CD90.1⁻CD90.2⁺ OT-II mice were mixed in a 1:1 ratio. 10⁶ cells were i.v. transferred into CD90.1⁺CD90.2⁻ WT mice which had been i.v. infected with 10⁵ LmOVA one day before. On d4 post transfer, spleen cells from infected recipients were incubated for 4 h with 10⁻⁶M of OVA_323-339 peptide or with PMA/ionomycin and stained intracellularly for CD40L, TNF-α, and IFN-γ. Figures show frequencies of CD40L⁺, IFN-γ⁺ and TNF-α⁺ cells among transferred OT-II T cells following stimulation with OVA_323-339 (a) and PMA/ionomycin (b). Bars represent mean ± SEM from 6 individually analyzed mice per group. The result is representative for 4 independent experiments.