Regulatory activity of CD4+CD25low/-GITR+and CD4+CD25highGITR-cells from HC differs from that of SLE patients . Inhibition of proliferation by CD4+CD25low/-GITR+ cells and CD4+CD25highGITR- cells observed in autologous (see Figure 5) and heterologous (see Figure 7) co-cultures is shown (A-D). **P <0.01 and ***P <0.001 according to Mann-Whitney U test comparing inhibition by CD4+CD25low/-GITR+ cells and CD4+CD25highGITR- cells. (E) Differences between regulatory activity exerted by CD4+CD25highGITR- and CD4+CD25low/-GITR+ Treg from each HC (circle) and SLE patient (triangle) is reported, as shown in right plots of Figures 5 and 7. Horizontal lines indicate mean differences. ***P <0.001, according to the Mann-Whitney U test comparing differences in HC and SLE.