Blocking TGF-β and IL-10 inhibits the regulatory activity of CD4+CD25low/-GITR+cells from SLE patients . (A-C) CFSE-labeled effectors, activated with cross-linked anti-CD3 Ab, were co-cultured with autologous unlabeled effectors (CD4+CD25-GITR-) (left) or unlabeled CD25-depleted (including CD4+CD25-GITR- and CD4+CD25low/-GITR+) (right) at a 1:3 cell ratio. In panel B, blocking anti-TGF-β Ab (0.5 μg/ml) and, in panel C, blocking anti-IL-10 Ab (30 ng/ml) were added. Proliferation was evaluated after 4 days with flow cytometry. Histograms on the left show inhibition of proliferation by CD4+CD25low/-GITR+ in the presence (B, C) or absence (A) of blocking Abs. One representative SLE patient is shown. Histograms on the right show the mean inhibitory effect of blocking anti-TGF-β Ab (B) and anti-IL-10 Ab (C) on the regulatory activity of CD4+CD25low/-GITR+ cells, observed in cells from three SLE patients ± SEM (bars). **P <0.01 according to the Mann-Whitney U test.