CXCR3-expressing ICOS⁺ T_reg cells adopt a Th1-like phenotype in draining LN.

T-bet and CXCR3 co-expression was assessed in ICOS⁺ T_reg cells from 4 week old WT BDC2.5 mice (A). T-bet expression (MFI) between ICOS⁺ and ICOS^- subsets within T_reg cells (B). NOD.TCRα^-/- mice received BDC2.5 CD4⁺CD25⁺ T_reg or CD4⁺CD25^- T_eff cells (0.75X10⁵) at the indicated T_reg/T_eff cell ratios. When mice receiving T_eff cells alone became hyperglycemic (>33mmol/L), mice were sacrificed and the frequency of (C) T-bet⁺ and (D) IFN-γ⁺ cells within the ICOS⁺ T_reg subset was assessed. (E) NOD.TCRα^-/- mice received WT T_eff (7.5X10⁵) cells and ICOS^-/+ T_reg (7.5X10⁵) cells isolated from pooled LN and spleen. 10 days post-transfer, cell suspensions were obtained from the pancreas and draining pLN and IFN-γR expression (MFI) was compared between ICOS⁺ and ICOS^- T_reg cells. (3B-3D n = 4, 3E n = 5)