Expression of PD-1, LAG-3 and CD39 in Peripheral Blood CD4+CD25+Foxp3+ T Cells of Patients with Gastric Malignant Tumor

Abstract

Objectives: To explore the expression proportion and absolute count of CD4+CD25+Foxp3+ regulatory T (Treg) cells, programmed cell death protein 1 (PD-1), lymphocyte-activation gene 3 (LAG-3) and cluster of differentiation 39 (CD39) in peripheral blood of patients with gastric malignant tumor. Methods: Peripheral blood samples were collected from 50 patients with gastric malignancy (tumor group) and 15 healthy controls (control group). The absolute count of leukomonocyte, and the proportion of CD3+ T cells and CD4+ T cells, the proportion and absolute count of Treg cells, PD-1, LAG-3 and CD39 subsets of Treg cells were assessed by flow cytometry in the two groups. Moreover, the correlation between Treg cells and their immune checkpoints was analyzed. Results: Compared with the healthy control group, total leukomonocyte [(1.19 ± 0.37) × 10³/μL vs (2.04 ± 0.29) × 10³/μL] and CD3+ T cell proportion [31.85% (18.63%, 43.61%) vs 45.08% (41.77%, 53.70%)] in peripheral blood of patients with gastric malignant tumor were decreased (p < 0.05), while CD4+ T cell proportion was not statistically significant (p > 0.05). The proportion of Treg cells in the tumor group was higher than that in the healthy control group [10.06% (7.04%, 14.14%) vs 3.39% (2.97%, 4.38%)] (p < 0.05). The proportion and absolute count of PD-1+Treg, LAG-3+Treg and CD39+Treg cells in the tumor group were higher than those in the healthy control group (p < 0.05). The proportion of Treg and PD-1+Treg cells, CD39+Treg and PD-1+LAG-3+Treg cells, LAG-3+Treg cells and PD-1+LAG-3+Treg cells, and PD-1+Treg and PD-1+LAG-3+Treg cells were positively correlated in the tumor group (p < 0.05). Conclusions: The expression of Treg cells in the peripheral blood of patients with gastric malignant tumor increased. PD-1, LAG-3 and CD39 molecules were highly expressed and co-expressed in Treg cells, which had a complex regulatory relationship with each other. Therefore, it is crucial to monitor the characteristics of tumor microenvironment and biomarkers of immune efficacy represented by Treg cells.