IFN-γ regulates CXCR3 expression by ICOS⁺ T_reg cells and their homing to islets.

NOD.TCRα^-/- mice received BDC2.5 CD4⁺ T cells (7.5X10⁵) and, (A) and the percent CXCR3⁺ and IFN-γR⁺ cells among total T_reg cells in pancreas and draining LNs was assessed at the indicated times post-transfer. (B) Correlation between percent CXCR3⁺ and IFN-γR⁺ in pancreas and draining LN at all points examined. (C) BDC2.5 CD4⁺ T cells were stimulated with various concentrations of recombinant IFN-γ, and STAT1 phosphorylation was assessed by flow cytometry and compared between ICOS⁺ and ICOS^- subsets of T_reg cells. (D) NOD.TCRα^-/- mice received T_eff (7.5X10⁵) cells and were injected i.p. with either PBS or anti-IFNγ Ab (XMG1.2) on days -1, 1, 3, 5 and 7 post transfer. Mice were sacrificed when the PBS group displayed hyperglycemia (>33mmol/L). Cell suspensions of the pancreatic draining LN were obtained and the percent CXCR3⁺ among pT_reg cells was compared between groups. (6A, 6B, 6D n = 5. 6C n = 2).