Fig. 7

Correlation between programmed death-1 (PD-1) expression and the Disease Activity Score in 28 joints based on C-reactive protein (DAS28-CRP). The expression of PD-1 in CD4⁺CXCR5⁺ follicular helper T (Tfh) cells was positively correlated with DAS28-CRP (r = 0.323, P = 0.033)