Differential induction of CD25 and FOXP3 expression by retinoic acid (RA) and (transforming growth factor beta (TGFβ) in healthy controls (HCs) and systemic lupus erythematosus (SLE) patients. (a) Representative fluorescence activated cell sorter (FACS) plots showing FOXP3 and CD25 staining in CD4+ gated peripheral blood mononuclear cells (PBMCs) after three days stimulation with anti-CD3 and anti-CD28 with or without RA and in the presence of 0, 1, or 20 ug/ml of TGFβ. In the (b-d) panels, CD25- regulatory T cells (Tregs) are shown on the left, Tregs in the middle, and CD25+ FOXP3- CD4+ T cells on the right. (b) RA-induced expansion in the presence of 0, 1, or 20 ug/ml of TGFβ. The graphs show the ((RA - no RA)/no RA) values for each TGFβ concentration. (c) TGFβ-induced expansion in the absence of RA. The graphs show the ((TGFβ - no TGFβ)/no TGFβ) values for each concentration of TGFβ. HCs are represented by white symbols and SLE patients by black symbols.