We first found that the expressions of B cell activation markers (CD25: 56.34% ± 2.53% vs. 28.78% ± 2.29%, P < 0.01; CD69: 1.51% ± 0.24% vs. 0.71% ± 0.18%, P < 0.05; CD40: 87.85% ± 2.53% vs. 77.13% ± 4.12%, P < 0.05; Figure 4c) were significantly upregulated in RA patients, suggesting B cells are in an activated state in RA. The gene discussed is CD40; the disease is rheumatoid arthritis.