CD4 and neoplasm: Further analysis in the current study uncovered the antitumor immune response and anti-metastatic effects of IM@ZP under NIR laser irradiation in vivo, which was attributed to the enhanced photothermal immunotherapy effect upon downregulation of PD-L1 protein, and the resultant promotion of tumor infiltrating CD8 +  and CD4 +  T cells and NK cells.