SIRPa: A key player in innate immunity

Signal regulatory protein alpha (SIRPa) is a crucial inhibitory regulator expressed on the surface of myeloid cells, including macrophages, dendritic cells, monocytes, neutrophils, and microglia. SIRPa plays an indispensable role in innate immune and adoptive immune responses in cancer immunology, tissue homeostasis, and other physiological or phycological conditions. This review provides an overview of the research history, ligands, signal transduction pathways, and functional mechanisms associated with SIRPa. Additionally, we summarize the therapeutic implications of targeting SIRPa as a promising novel strategy in immuno-oncology.