For example, the number of circulating Tfh cells (CXCR5+ICOS+CD4+ cells or CXCR5+PD-1+CD4+ cells) has been shown to increase in a subset of SLE patients in line with the diversity and concentration of autoantibodies and SLE severity (81). This evidence concerns the gene CXCR5 and systemic lupus erythematosus.