At the protein level, the expression of FoxP3 and CTLA-4 was similar to those seen in CD4+CD25low/-GITR+ cells from HC [36], demonstrating that CD4+CD25low/-GITR+ cells from SLE patients display a Treg phenotype, as demonstrated in HC (Figure 4A, B). Here, TNFRSF18 is linked to systemic lupus erythematosus.