There was a positive correlation between PD-1 and PD-L1 expression on peripheral blood CD4+CD25+CD127low Tregs among patients with active pulmonary TB (r = 0.435, P=0.016) (Figure 4(a)), and the proportion of peripheral blood CD4+CD25+CD127low Tregs negatively correlated with PD-1 (r = ‒0.344, P=0.024) and PD-L1 expression among patients with active pulmonary TB (r = ‒0.310, P=0.043) (Figures 4(b) and 4(c)). The gene discussed is CD4; the disease is pulmonary tuberculosis.