Knockdown of HAT1 can upregulate tumor infiltration of immune effectors such as CD45+CD4+ and CD45+CD8+ T cells, suppress the infiltration of CD11b+Gr1+ myeloid cells in tumors and decrease the expression level of PD-L1, which may inhibit tumor proliferation and promote the efficacy of the immune checkpoint blockade (40). The gene discussed is CD4; the disease is neoplasm.