TNFRSF18 and systemic lupus erythematosus: In fact, our results confirm an active role of CD4+CD25low/-GITR+ in T-cell suppression because, as observed in HCs, SLE CD4+CD25low/-GITR+ cells produce high amounts of TGF-β and IL-10 and their neutralization, by blocking Abs, inhibits their suppressive activity.