FIGURE 2. The in vivo and in vitro suppressive function of CD4⁺Foxp3⁺ T_reg cells was not compromised but rather enhanced by a modest reduction in CTLA4 expression.

(A) Flow cytometry plots of the spleen of B6.Foxp3^sf mice reconstituted with naïve T_reg cells from CTLA4RNAi or PL4 vector control donors. Donor T_reg cells were marked with ubiquitously expressed GFP in the PL4 and CTLA4RNAi transgenic lines (numbers represent percentages of gated CD4⁺ and CD8⁺ populations). (B)In vivo suppression of CD4⁺ and CD8⁺ T-cell activation determined by analyses of the CD44^hiCD62L^low subset. Each data-point represents one animal (line indicating average of the group). (C–D) Histopathological scores and representative H&E sections of the livers of the B6.Foxp3^sf mice reconstituted with T_reg cells (original magnification: x12.5) assessed for lymphocytic infiltration (n=4 per group from 4 independent experiments; Mean ± SEM). (E) Summarized results from in vitro T_reg suppression assays (n=5 from 3 independent experiments; Mean ± SEM). Control T_reg cells were from transgene-negative littermates or age- & sex-matched PL4 vector transgenic mice. *p<0.05; **p<0.01; ***p<0.005.