Figure 1 (See previous page).

IL-12 but not IL-21 induced the differentiation of human naive CD4⁺ (T)cells into Th1 and Tfh co-expressing cells. Human naive CD4⁺ T cells from cord blood were stimulated for 5 d with or without anti-CD3 and anti-CD28 mAbs in the presence or absence of IL-12, IL-21 or IL-12 plus IL-21. The cells were harvested and rested for 2 d with IL-2. The cells were re-stimulated for 6 h with PMA and ionomycin in the presence of BFA. The expression of IL-21 and IFN-γ was detected by FACS. A representative result of different cytokines on the development of Th1 and Tfh cells was shown (A). Statistical data of percentage of IL-21⁺CD4⁺ (B), IFN-γ⁺CD4⁺ (C), IFN-γ⁻IL-21⁺ (D), IFN-γ⁻IL-21⁺ (E) and IFN-γ⁺IL-21⁺ (F) CD4⁺ T cells were mean ± SD from 5 independent experiments as described in A. Cell surface expression of CXCR5, PD-1, ICOS and CXCR3 was assessed by surface staining and a representative result was shown (G). P < 0 .05 was considered significant.