The percentages of circulating CD31+CXCR4+ cells in total CD3+ T cells (Tang) and CD31+CXCR4+ cells in CD4+ T cells (CD4+ Tang) tended to be slightly higher in SLE patients when compared to HC; however, the differences did not reach statistical significance (Figure 1(b)). Here, CXCR4 is linked to systemic lupus erythematosus.