CD4 and neoplasm: The exosomes secreted by CT26 cells are loaded with ICG and R837, and under laser irradiation, the tumor-associated antigens of immunogenic cell death (ICD) are generated, the maturation of DCs is promoted under R837, and the tumor invasion of CD8+ T cells and CD4+ T cells is enhanced, so as to realize the antitumor effect of PTT (photothermal therapy) combined with immunotherapy (Cheng et al., 2021).