The rheumatoid factor and the percentage of HVEM+CD4+ T lymphocytes showed a statistically significant negative correlation in RA patients (r = -0.453, p = 0.039), as did the swollen joint count and the percentage of BTLA+CD8+ T lymphocytes (r = -0.501, p = 0.021). This evidence concerns the gene CD8A and rheumatoid arthritis.