Fig. 1

PD-1 levels in synovial T cells are higher than in peripheral blood T cells. Gating strategy for different T cell subsets (A). Flow cytometry was performed on T cells isolated from synovial fluid (SF) and matched peripheral blood (PB) T cells from patients with rheumatoid arthritis (RA) (B–E). Flow cytometry analysis of the expression levels of PD-1 and LAG-3 was performed on naïve (N), central memory (CM), effector memory (EM), terminally differentiated memory cells (TEMR) CD4, and CD8 T cells (B–E). Violin plots quantification of the percentages of CD4⁺PD-1⁺ cells in healthy controls (HC) PB, RA PB, and RA SF out of all CD4⁺ cells (Fi). Violin plots quantification of the percentages of CD4⁺PD-1⁺ cells in HC PB, RA PB, and RA SF out of all CD4⁺ cells within N, CM, EM, and TEMRA subsets (Fii). Violin plots quantification of the percentages of CD4⁺PD-1⁺ cells expressing LAG3, ICOS, or TIGIT in HC PB, RA PB, and RA SF out of all CD4⁺PD-1⁺ cells (Fiii). Violin plot quantification of the percentages of CD8⁺PD-1⁺ cells in healthy controls HC PB, RA PB, and RA SF out of all CD8⁺ cells (Gi). Violin plot quantification of the percentages of CD8⁺PD-1⁺ cells in HC PB, RA PB, and RA SF out of all CD8⁺ cells within N, CM, EM, and TEMRA subsets (Gii). Violin plot quantification of the percentages of CD8⁺PD-1⁺ cells expressing LAG3, ICOS, or TIGIT in HC PB, RA PB, and RA SF out of all CD8⁺PD-1.⁺ cells (Giii). Statistical significance was determined using ordinary 1-way ANOVA, Tukey’s multiple comparisons test; *p < 0.05, n = 3–5