B2M and neoplasm: Subsequently, MHC-I molecules are upregulated for antigen-presenting functions, whereas LILRB1 is downregulated.76 Recently, it was found that the binding between β2m of MHC-I expressed on the surface of tumor cells and LILRB1 on the surface of tumor-associated macrophages (TAMs) inhibits the phagocytic activity of TAMs, leading to decreased immune surveillance and enhanced immune escape of tumor cells.10