Suppressive activity of TCR + CD4 + EGFP + and TCR + CD8 + EGFP + cells in an MLR. An MLR was performed by co-culturing in a 1:1 ratio spleen CD4 + CD25 − Tconv cells from SD/Crl rats (MHC haplotype u) with enriched spleen APCs from Lewis 1A (MHC haplotype a) rats. Spleen Tregs from wild-type (WT) or Foxp3-EGFP SD/Crl rats were sorted based on their surface phenotype using previously defined markers. For CD4 + Tregs, TCR + CD4 + CD25 + CD127 low/− and for CD8 + Tregs, TCR + CD8 + CD45RC low/− . CD4 + and CD8 + Tregs were then sorted based on the expression or not of EGFP. The four populations of Tregs, CD4 + EGFP + , and EGFP − as well as CD8 + EGFP + and EGFP − were added to the MLR in a 1:1 or 1:2 Tregs to CDP-670 labeled Tconv cells. Values are expressed as mean % ± SEM of suppression normalized to MLR proliferation in the absence of Tregs (0% inhibition of proliferation). n = 4. Student’s t test * P < 0.05, ** P < 0.01, *** P < 0.001, and **** P < 0.0001
