The expression and significances of PD-1 and PD-L1 in peripheral blood T cells of patients with acute exacerbation of chronic obstructive pulmonary disease

Objective To investigate the expression of PD-1 and PD-L1 in peripheral blood T cells of patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD) and its relationships with clinical indicators and prognosis. Methods A total of 79 patients with AECOPD and 30 healthy examiners in our hospital from May 2017 to May 2018 were enrolled as the subjects. The expression levels of PD-1 and PD-L1 in peripheral blood CD4⁺ T cells and CD8⁺ T cells were detected by flow cytometry, and the relationships with clinical indicators were analyzed. The prognostic factors were analyzed by Cox regression model. Results Compared with healthy subjects, CD4⁺ T in peripheral blood of patients with AECOPD increased significantly, CD8⁺ T decreased significantly(all P<0.05). The expression levels of PD-1 and PD-L1 in AECOPD patients were higher than that of healthy people(P<0.05). The expression levels of PD-1 and PD-L1 were correlated with smoking, expectoration volume, bronchial infection, shortness of breath, PaO₂, PaCO₂, and antioxidant use(all P<0.05). Smoking, expectoration volume, degree of bronchial infection, shortness of breath, PaO₂, PaCO₂, antioxidant use or not, and the expressions of PD-1 and PD-L1 were independent prognostic factors in AECOPD patients(all P<0.05). Conclusion The levels of PD-1 and PD-L1 in peripheral blood CD4⁺ T cells and CD8⁺ T cells are increased in AECOPD patients, and they are closely related to clinical indicators and prognosis. It is speculated that PD-1 and PD-L1 may be involved in the occurrence and development of AECOPD patients.