Co-signaling molecules play an important role in T cells. This study was designed to investigate PD-1 and Tim-3 expression on T cells and the relationships between PD-1 and Tim-3 expression and immune evasion in patients with gastric cancer.
Using multicolor flow cytometry, we analyzed PD-1 and Tim-3 expression on CD8+ T cells obtained from peripheral blood mononuclear cells (PBMCs) and gastric cancer tissue.
Significantly more PD-1+ and Tim-3+ CD8+ T cells in peripheral blood were found in gastric cancer patients than in healthy controls. PD-1+ CD8+ T cells were significantly correlated with Tim-3+ CD8+ T cells in peripheral blood from the gastric cancer patients (r = 0.29, p = 0.036). Furthermore, significantly greater numbers of PD-1+ and Tim-3+ CD8+ T cells were seen in the gastric cancer tissue samples than in the PBMCs. CD8+ T cells positive for both PD-1 and Tim-3 produced significantly less IFN-gamma than cells negative for both and cells positive for PD-1 and negative for Tim-3.
An increased number of PD-1+ and Tim-3+ CD8+ T cells is closely related to impaired function of CD8+ T cells in gastric cancer patients.