CD4 and rheumatoid arthritis: To analyze the frequency of circulating peripheral blood CD4+ cTfh and circulating CD8+ follicular T cells in HCs, RA-risk individuals, and early RA patients, we first analyzed the frequencies of CXCR5+ and PD-1+ cells within CD4+ and CD8+ T cells (see gating in Figure 1A and Supplementary Figure S1 (unstained negative control)).