scRNA-seq analysis of pan-cancer myeloid cells revealed that LAMP3 + dendritic cells are widely present; macrophages with high expression of CD73 in glioblastoma are associated with immunosuppression and poor anti-PD-1 efficacy; high expression of IL-8 in myeloid cells is associated with poor ICB efficacy; high scores of specific macrophage clusters in breast cancer are associated with good prognosis, providing targets and markers for immunotherapy. Here, LAMP3 is linked to breast carcinoma.