Significance of the frequency of CD4+CD25+CD127- T-cells in patients with pulmonary tuberculosis and diabetes mellitus

Background and objective: Pulmonary tuberculosis and diabetes mellitus (DM) are closely associated. The objective of this study was to determine whether the expression of CD4+CD25+CD127? T‐cells (regulatory T‐cells (Treg)) is associated with diabetic pulmonary tuberculosis. Methods: Flow cytometry was used to determine the frequencies of CD4+CD25+ and CD4+CD25+CD127? T‐cells in peripheral blood, bronchoalveolar lavage fluid (BALF) and pleural effusions from 120 patients (30 with pulmonary tuberculosis and DM (TBDM), 30 with pulmonary tuberculosis without DM (TB), 30 with tuberculous pleurisy without DM (TBP) and 30 healthy volunteers). The concentrations of interferon (IFN)‐γ and interleukin (IL)‐10 in BALF and pleural effusions were determined by enzyme‐linked immunosorbent assay. Results: Treg frequencies in peripheral blood were significantly higher in patients with TBDM, TB and TBP than in the control group, with the frequency in TBDM being the highest (P < 0.01 for all). In TBP patients, Treg frequencies were significantly lower in pleural effusions than in peripheral blood. In TB patients, Treg frequencies in BALF and peripheral blood were not significantly different. However, in TBDM patients, Treg frequencies were significantly higher in BALF than in peripheral blood. IL‐10 expression was significantly higher, and IFN‐γ expression was significantly lower in BALF of TBDM patients compared with BALF and pleural effusions of TB patients. Conclusions: In patients with pulmonary tuberculosis and DM, the imbalance between Treg and effector T‐cells at pathological sites may be associated with weakened immunity and clinical manifestations of TB.