Using this strategy, it was shown in human SLE that circulating TFH cells (cTFH) defined as CD4+CXCR5+PD-1+/high and/or ICOS+ T lymphocytes are expanded in lupus patients and their presence correlates with a more severe disease phenotype [59–64]. The gene discussed is CXCR5; the disease is systemic lupus erythematosus.