PRF1 and rheumatoid arthritis: A higher percentages of CD8+ T cells in RA patients expressed Granzyme B (RA: 28.40 ± 5.5% vs HC: 6.73 ± 6.0%; p < 0.05), Perforin (RA: 28.97 ± 6.5% vs HC: 17.17 ± 8.5%), TNFα (RA: 16.47 ± 0.3% vs HC: 6.47 ± 1.5%; p < 0.01) and IFNγ (RA: 24.07 ± 1.9% vs HC: 0.03 ± 0.01%; p < 0.001) was observed in RA patients in comparison to the healthy controls (Fig. 3b and Supplementary Fig. 2).