The results suggested that the expression of PD-1mRNA and PD-1 protein in serum was significantly lower in PD-1 and PD-1+RA group (Figure 4(a): PD-1mRNA: 0.04 ± 0.02, 0.051 ± 0.021; Figure 4(b): PD-1 protein: 0.82 ± 0.27, 0.97 ± 0.33) compared with the control group (Figure 4(a): PD-1mRNA: 0.78 ± 0.26; Figure 4(b): PD-1 protein: 3.67 ± 1.13). The gene discussed is PDCD1; the disease is rheumatoid arthritis.