CD4 and systemic lupus erythematosus: Patients with SLE and HCs were recruited, and the frequencies of CXCR5+CD4+ cTfh cells and their subsets (cTfh1: CXCR3+CCR6–, cTfh2: CXCR3–CCR6–, cTfh17: CXCR3–CCR6+) were compared in peripheral blood mononuclear cells (PBMCs).