PDCD1 and tuberculosis: Flow cytometry detected lower PD-1 (6.13% ± 3.53% vs. 24.78% ± 7.73%, P < 0.05) and PD-L1 levels (2.97% ± 2.00% vs. 9.23% ± 5.76%, P < 0.05) on peripheral blood CD4+CD25+CD127low Tregs among the TB group than in the control group (Figure 3).