Background and Aims: Tumor immune cell infiltration plays a key role in the progression and prognosis of gastric cancer (GC). However, the regulatory genes of immune cell infiltration that affect the prognosis of GC are still unclear at present. This study was conducted to identified the immune genes associated with the prognosis of GC by co-expression network analysis and deconvolution analysis.  
Methods: GC mRNA expression data were downloaded from TCGA database and the proportions of immune cells in each sample were determined using the CIBERSORT deconvolution algorithm. A co-expression network was also constructed, and then, the immune-related prognostic genes were identified by combining the Kaplan-Meier method.
Results: Of the 22 types of immune cells included in the analysis, 11 were significantly higher in tumor tissue than those in normal tissue (all P<0.05). Survival analysis for the above 11 types of immune cells showed that infiltration of T cells CD4 memory resting and T cells regulatory was significantly correlated with survival rate in GC patients (all P<0.05). Based on the above results, the co-expression network analysis revealed that the genes in the turquoise module were most significantly correlated with the above two types of cells, and then, 3 prognostic genes associated with memory CD4 T cells (CGB5, LINC00106, LINC00392) and one associated with regulated T cells (UPK1B) were identified (all P<0.05). 
Conclusion: The 4 prognostic genes identified in this study may play important roles in the progression and prognosis of GC, and these genes may serve as potential targets for immunotherapy of GC by influencing the tumor immune process.