Figure 5. CD25⁺ Tfh cells express high levels of transcription factor cMaf to promote cytokine responses and low levels of Blimp-1 to maintain a Tfh-cell phenotype in the absence of Bcl6.

(A) cMaf expression in PD1⁺ (Tfh) andPD1- (non-Tfh) tonsil CD4⁺T cells was determined by flow cytometry. (B) Purified tonsil Tfh CD4 T cells (CXCR5⁺PD1⁺) were treated with or without IL-2 (100U/mL) for 24 h, then cMaf expression was determined by flow cytometry. (C) Purified tonsil Tfh CD4⁺ T cells (CXCR5⁺PD1⁺) were treated without or with IL-2 at different concentrations for 24 h and protein expression was analyzed by western blot for cMaf, P-STAT3, Bcl6, Blimp-1, P-STAT5. Data are representative of 3 independent experiments. β-actin was used as a loading control. (D, E) cMaf expression was measured on T-cell subsets using (D) fresh or (E) IL-2-treated tonsil CD4⁺T cells. (F) cMaf expression was determined in tonsil Tfh cells treated with medium, IL-2 or Dexamethasone (Dex) for 24 h. (G–I) Purified tonsil Tfh cells were treated with medium, IL-2 or Dexamethasone (Dex) for 24 h and stimulated with PMA plus Ionomycin for 4 h;(G) IL-21, (H) IL-10 or (I) IL-17 production was detected by intracellular staining. (A, B, D–F) MFI was calculated as: (MFI (specific mAb) – MFI (isotype control))/MFI (isotype control).(A, B, D–I) Data are expressed as mean+SEM (n=7) and are representative of 3 independent experiments. P < 0.05 was considered to be significant; Student’s t test.