We found that the PLK4 expression was positively correlated with immune infiltration of most immune cells, including cancer-associated fibroblast, neutrophils, myeloid dendritic cells, active CD4+ T cells, CD8+ T cells, endothelial cells, monocytes, and macrophage M1, negatively correlated with NK cells and macrophage M2, and significantly correlated with genetic markers of CD8+ T cell, T cell, monocyte, TAM, M1 macrophage, M2 macrophage, neutrophils, NK cells, dendritic cells, Th1 cells, and Th2 cells. The gene discussed is CD8A; the disease is cancer.