HAVCR2 (TIM-3) functions as a critical immune checkpoint receptor that regulates both innate and adaptive immune responses through multiple mechanisms. The protein serves as a negative regulator of T cell activation, attenuating TCR-induced signaling by blocking NF-κB and NFAT activities, resulting in decreased IL-2 secretion 1. TIM-3 forms heterodimeric interactions with CEACAM1, which is essential for its inhibitory function and facilitates its surface expression 2. The receptor binds multiple ligands including galectin-9, phosphatidylserine, HMGB1, and CEACAM1, with different ligand interactions producing distinct functional outcomes 3. Post-translational regulation occurs through palmitoylation by DHHC9 at Cys296, which stabilizes the protein and promotes immune exhaustion 4. Beyond T cells, TIM-3 regulates myeloid cell function, with TIM-3+ macrophages showing anti-inflammatory and protumorigenic phenotypes 5. In disease contexts, TIM-3 marks exhausted T cells in chr5 infections and tumors, making it an attractive immunotherapy target 2. The protein also contributes to diabetic nephropathy pathogenesis by promoting macrophage activation via NF-κB/TNF-α signaling 6. TIM-3's dual regulatory roles position it as a key mediator of immune tolerance and exhaustion with significant therapeutic implications.