CD209 (DC-SIGN) is a C-type lectin pattern recognition receptor expressed on dendritic cells and macrophages that mediates pathogen recognition and immune regulation 1. The molecule recognizes high-mannose N-linked oligosaccharides on various microbial pathogens in a calcium-dependent manner, including Mycobacterium tuberculosis, Helicobacter pylori, and Leishmania species 2. CD209 serves as both a pathogen recognition receptor and an alternative entry point for enveloped viruses including SARS-CoV-2, dengue virus, and Zika virus, though in vivo studies suggest it plays only a partial role in viral infection 3. In macrophage biology, CD209 expression marks alternatively activated (M2) macrophages with high endocytic capacity 4. The molecule is essential for dendritic cell migration and T cell activation, contributing to both primary immune responses and immunoregulation 1. Genetic variants in CD209 promoter regions (-871A/G and -336A/G polymorphisms) are associated with tuberculosis susceptibility, particularly in Asian populations, where certain genotypes confer increased risk 56. Elevated CD209 plasma levels show association with increased varicose vein risk 7. CD209 expression on tumor-associated macrophages correlates with distinct functional phenotypes related to phagocytosis and angiogenesis 8.