Analyses of circulating T cells from patients with SLE have demonstrated an increase in circulating CXCR5+ PD-1hi T follicular helper (Tfh) cells, as well as a prominent increase in circulating CXCR5− PD-1hi T peripheral helper (Tph) cells (3–7). Here, CXCR5 is linked to systemic lupus erythematosus.