Figure 3. Human γδ Treg cells induce senescence in Th1 and Th17 cells.

(A) Suppression of Th1 and Th17 cell proliferation by γδ Treg cells. CD4-C1 effector T cells displayed no suppressive activity, and served as a negative control. Th1 or Th17 cells established from TILs were co-cultured with γδ Treg or control T cells at a ratio of 10:1. The proliferation of Th1 or Th17 cells in the presence of anti-CD3 antibody was determined by [³H]-thymidine incorporation assays. (B) and (C) γδ Treg cell treatment significantly increased SA-β-Gal positive T cell populations in Th1 or Th17 cells. Th1 or Th17 cells cultured in medium only or co-cultured with CD4-C1 effector T cells had little or no SA-β-Gal expression. CFSE-labeled Th1 or Th17 cells were incubated alone or co-cultured with γδ Treg or CD4-C1 T cells at a ratio of 5:1 in the presence of plate-bound anti-CD3 (2 µg/ml) for 3 or 5 days. The treated Th1 or Th17 cells were purified by FACS and stained with SA-β-Gal staining reagents after an additional 3 day culture. The SA-β-Gal positive T cells (5 day co-culture) were identified with dark blue granules as the arrows indicate in (B). (D) Decreased expression of CD27 and CD28 in Th1 and Th17 cells treated by γδ Treg cells. Cell treatment and procedure were the same as in (B). CD27 and CD28 expression in treated Th1 and Th17 cells (5 day treatment) were analyzed by FACS.