Distribution characteristics and clinical significance of circulating CD8 + CD28 - regulatory T cells in the peripheral blood of patients with pulmonary tuberculosis

Abstract Background: Regulatory T cells (Treg cells) in the peripheral blood of patients with pulmonary tuberculosis (PTB) may be closely related to the progression of PTB. In this study, the distribution characteristics and clinical importance of CD8+CD28- Treg cells in patients with tuberculosis were systematically analyzed, and the role and importance of CD8+CD28- Treg cells in influencing the immune response and progression of tuberculosis were discussed, which will provide immunological indices and reference values for the clinical diagnosis of tuberculosis.Methods: Flow cytometry, sputum smears and CT imaging were used to analyze the distribution characteristics of CD8+CD28- Treg cells in the peripheral blood of patients with PTB and the correlation between CD8+CD28- Treg cells and clinical and immune indices.Results: Compared with those in the healthy control (HCs) group, the percentages of CD4+CD25high and CD8+CD28- Treg cells in the peripheral blood of patients with PTB increased significantly. Further analysis showed that compared with that in the HCs group, the percentage of CD4+CD25high Treg cells in the Stage II group increased significantly. The percentages of CD4+CD25high and CD8+CD28- Treg cells increased significantly in patients in the Stage II group. The proportion of CD8+CD28-Treg cells was directly proportional to the positive degree of sputum smears, while CD4+CD25high Treg cells did not show this effect.The correlations between the percentage of CD4+CD25high and CD8+CD28- Treg cells and the percentage of lymphocyte subsets were examined. CD8+CD28-Treg cells were negatively correlated with CD4+T cells and positively correlated with the CD8+T cell ratio in the HCs and PTB groups. CD4+CD25highTreg cells were positively correlated with CD4+T cells only in the PTB group.Conclusions: This study was the first to show that the proportion of CD8+CD28- Treg cells in the peripheral blood of patients with PTB was significantly increased, and the increase in CD8+CD28-Treg cells was related to the progression of PTB, which may affect the proportion of immune cell subsets by inhibiting the immune response, resulting in the progression of PTB.