The shifted balance between circulating CXCR5+PD-1low Treg and Tfh cells correlated not only with reduced serum IL-2, IL-10, and increased IL-21 levels in patients but also with clinical SLE parameters, e.g., ESR, anti-dsDNA antibodies, and disease activity (SLEDAI Scores). The gene discussed is CXCR5; the disease is systemic lupus erythematosus.