Figure 2.

Th1 cells from T-CD4 T cells produce the Th2 cytokine IL-4 as well as IFN-γ. Sorted naive (CD45RB^hiCD44^lo) CD4 T cells from WT, CIITA^Tg, and CIITA^Tg/CIITA^−/− mice were cultured under neutral, Th1-, or Th2-skewing conditions for 6 d, as described in Materials and methods. Differentiated cells were subsequently restimulated with plate-coated anti-CD3 overnight, and culture supernatants were collected and analyzed for IFN-γ and IL-4 production by ELISA (A). The error bars represent the mean ± SD. For intracellular cytokine analysis (B), differentiated neutral, Th1, or Th2 cells were restimulated with PMA plus ionomycin for 5 h, as described in Materials and methods. After fixation and permeabilization, the cells were stained with PE-conjugated anti–IFN-γ and allophycocyanin-conjugated anti–IL-4 and analyzed by FACS. Numbers in the dot plots represent the percentages of cytokine-positive CD4 T cells. All experiments were repeated at least twice.