As shown in Fig. 8A-F, CLDN18 was significantly associated with several biomarkers of inhibitory immune cells such as tumor-associated macrophages (TAMs; CD68, CCL2 and IL10, p < 0.0001), M2 macrophages (CD163, MS4A4A and VSIG4, p < 0.01), T helper cells 17 (STAT3, IL21R and IL23R, p < 0.0001), regulatory T cells (FOXP3, CCR8 and IL2RA, p < 0.0001), myeloid-derived suppressor cells (CD33 and ITGAM, p < 0.0001) and exhausted T cells (PDCD1, CTLA4 and LAG3, p < 0.01). The gene discussed is PDCD1; the disease is neoplasm.