In this study, we found that expression of LEP, DLX2, CLSTN2, and REG3A are correlated with immune infiltrating levels of CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and DCs in COAD, indicating that these four prognosis-associated genes expression levels could also reflect immune status, which partially explains that LEP, DLX2 and CLSTN2 are predictors of poor outcome while REG3A indicates better outcome and lower probability of distant metastasis in COAD. The gene discussed is CD8A; the disease is colon adenocarcinoma.