On the differentiation status of the T cells, we found statistically significant differences in the percentage of effector memory cells (EM, CD3+CD45RA−CD62L+) [23.78 (14.92–30.72), 14.14 (9.95–18.07), and 13.18 (10.09–18.39), p < 0.001 and p < 0.001] between the JAKi patients, healthy controls, and RA control group and among the central memory cells (CM, CD3+CD45RA+CD62L+) [31.87 (23.60–38.95) and 38.94 (33.12–47.11), p = 0.008] between the JAKi patients and healthy controls. The gene discussed is SELL; the disease is rheumatoid arthritis.