CD4 and neoplasm: To assess whether PRDX1 expression influences immune cell infiltration, we performed IHC staining for T cells and the M2 macrophage marker CD163 in tumor tissues. PRDX1‐KO mice exhibited increased infiltration of CD4+ and CD8+ T cells and a concurrent reduction in M2 macrophages, as indicated by decreased CD163 expression (Figure 2A,B).