MDSCs express RA genes and membrane-bound TGF-β but do not secrete inflammatory cytokines. (A) MDSCs express genes involved in RA metabolism. CD14⁺HLA-DR^−/low and CD14⁺HLA-DR⁺ cells were purified from freshly obtained blood. Gene expression was assayed by qPCR and normalized relative to expression of cyclophilin. Data shown are cumulative results from at least 4 independent experiments. (B) MDSCs express membrane-bound TGF-β. CD14⁺HLA-DR^−/low and CD14⁺HLA-DR⁺ cells were purified and cocultured with autologous CD4⁺ T cells. Cells were stained for membrane-bound transforming growth factor β (mTGF-β; black line) or isotype control (filled histogram) gated on CD14⁺ cells. Data shown are representative of 2 independent experiments (numbers indicate the MFI ratio for TGF-β staining). (C-F) MDSCs do not secrete inflammatory cytokines. CD14⁺HLA-DR^−/low and CD14⁺HLA-DR⁺ cells were cultured in the presence or absence of autologous CD4⁺ T cells at 2 different ratios [CD4:CD14 cells 1:1 (+) and 1:2 (++)]. Cytokines were tested at various time points using cytokine bead array. CD4⁺ T cells alone were used as controls. Shown are cumulative results from 2 independent experiments (*P < .05).