**4.4 LILRB1/2**

LILRB1 and LILRB2 are members of the leukocyte immunoglobulin-like receptor (LILR) family of receptors and are expressed on phagocytic cells such as macrophages, dendritic cells, and monocytes. These receptors serve as phagocytic checkpoints by regulating the phagocytic activity of these immune cells and modulating their ability to engulf and degrade pathogens and cellular debris. LILRB1 and LILRB2 can also regulate the immune response by modulating the activation and function of T cells and natural killer cells. In this way, they play a crucial role in maintaining immune homeostasis and preventing overactive immune responses. Studies have shown that LILRB1 and LILRB2 can also be exploited by cancer cells to evade the immune system and persist in the body. In light of these findings, the targeting of these receptors as phagocytic checkpoints has gained attention as a promising strategy in cancer immunotherapy. Inhibiting the activity of LILRB1 and LILRB2 has been shown to enhance the phagocytic activity of immune cells and improve their ability to target and clear cancer cells. This has led to ongoing research in the field of cancer immunotherapy to further explore the potential of targeting these receptors as phagocytic checkpoints [14, 67, 68].
