In this study, we used a tissue microarray (TMA) including 598 GC primary lesion specimens to investigate the expression of PD-L1 and quantify tumor-infiltrating CD3+, CD8+ T lymphocytes, FOXP3+ Tregs, and CD163+M2 macrophages density to determine their relationships with clinicopathological features and prognosis in GC patients based on different locations, clinicopathological stages, pathological classifications, chemotherapy strategies, and lymph node metastasis. The gene discussed is CD8A; the disease is gastric cancer.