Figure 7. BALB/c T_reg preferentially use TRAIL-mediated pathways compared to C57BL/6 T_regs.

(A) mRNA was isolated from freshly purified C57BL/6 or BALB/c T_conv cells and T_regs, cDNA synthesized and qPCR performed to assess Ctse expression. (B) Intracellular staining for CTSE was performed with purified C57BL/6 or BALB/c T_reg [Grey filled - secondary antibody only control; open histogram - C57BL/6 T_regs and closed histogram BALB/c T_regs]. (C) TRAIL staining was performed with Tnfsf10^−/−, wild type C57BL/6 or BALB/c T_regs, activated in presence of anti-CD3 and anti-CD28 coated latex beads with IL2 for 16h and surface TRAIL expression was detected by flow cytometry using a anti-mouse TRAIL antibody (MFI from three independent experiments, p-value:0.07). (D) Wild type C57BL/6 or BALB/c T_regs were mixed at 1:2 ratio with naïve wild type T_conv cells in the presence of anti-CD3 and anti-CD28 coated beads in the insert of a Transwell™ culture plate for 72h. Neutralizing antibodies against IL-10, IL-35 or a DR5-Fc protein were added to the Transwell™ assay at pre-determined concentrations as described in the methods. Freshly purified wild type responder T_conv were activated in the bottom chamber of a Transwell™ culture plate. Proliferation of the responder cells was determined by [³H]-thymidine incorporation. p-value *: < 0.05. Data represent 3–4 independent experiments.