Moreover, in B16 melanoma and Lewis lung carcinoma (LL2)-bearing mice, the synergistic application of anti-PD-L1 antibody with CD244-deficient macrophages significantly enhanced tumor rejection, surpassing the efficacy of CD244-deficient BMDM alone or a combination of WT BMDM and anti-PD-L1 antibody. Here, CD274 is linked to melanoma.