SLAMF9 (SLAM family member 9) is a cell surface immunoreceptor belonging to the signaling lymphocyte-activating molecule family, expressed broadly across immune cells 1. As a type-I transmembrane protein with conserved mammalian homologs 2, SLAMF9 plays multifaceted roles in immune regulation and tissue homeostasis. Mechanistically, SLAMF9 functions primarily through macrophage-mediated immune responses. Slamf9+ macrophages are induced following pathogenic challenge and demonstrate resistance to pathogen-induced damage 3. These cells coordinate with neutrophils to clear pathogens and subsequently differentiate into reparative phenotypes promoting inflammation resolution and tissue repair 3. Additionally, SLAMF9+ macrophages integrate into dendritic cell-T cell immunity hubs that defend against pulmonary infection 4. Functionally, SLAMF9 enhances TNF-α secretion in macrophages and modulates cell migration 5. In disease contexts, elevated SLAMF9 expression correlates with reduced survival across multiple cancer types 6, with enrichment in immunosuppressive tumor-associated macrophages 5. In colorectal cancer, SLAMF9 knockdown attenuates cancer cell proliferation and invasion 6. SLAMF9 has been identified as a therapeutic target in glioblastoma 7 and breast cancer 8, emerging as a potential immune checkpoint target for intervention.