SLAMF8 is a signaling lymphocyte activation molecule family member predominantly expressed in myeloid cells that functions as an immune checkpoint regulator 1. Primary function: SLAMF8 modulates innate and adaptive immune responses through noncanonical signaling pathways, regulating macrophage polarization, phagocytosis, oxidative burst, and cellular trafficking 1. Mechanism: SLAMF8 signals through multiple pathways including TLR4/NF-κB, PI3K/AKT, and JAK/STAT3, promoting M2 macrophage polarization and immunosuppressive phenotypes 234. Disease relevance: SLAMF8 dysregulation contributes to multiple pathologic conditions. In infectious disease, SLAMF8 activation in plasmacytoid dendritic cells modulates type I interferon responses to intracellular bacteria 5. In antiphospholipid syndrome, H3K4me3-mediated FOXJ2 upregulates SLAMF8, triggering TLR4/NF-κB signaling to promote thrombosis and inflammation 6. In Alzheimer's disease, SLAMF8-NINJ2 interaction activates neuroinflammation and oxidative stress 3. Clinical significance: SLAMF8 serves as a cancer-associated immune checkpoint. High SLAMF8 expression in colorectal and prostate cancers correlates with poor prognosis and immunotherapy resistance by suppressing CD8+ T cell function 27. SLAMF8 inhibition restores antitumor immunity and enhances immunotherapy sensitivity, positioning it as a therapeutic target 2. Additionally, SLAMF8 is a negative regulator of inflammation implicated in inflammatory bowel disease susceptibility 8.