PDCD1 and neoplasm: Conversely, the anti-tumor effects of IgA include: 1) IgA facilitates transcytosis, inhibits the RAS pathway, and enhances T cell-mediated cytotoxicity and neutrophil-mediated ADCC; 2) IgA modulates B cell subpopulations and PD-1 expression, promoting CD8+ T cell killing of tumor cells.