RNASE2, also known as eosinophil-derived neurotoxin (EDN), is a member of the RNase A superfamily and is predominantly expressed in eosinophilic leukocytes, where it is stored in large quantities within specific cytoplasmic granules. Structurally, RNASE2 possesses a catalytic domain that confers ribonuclease activity, which enables its primary role in the host immune response against viral infections by directly degrading viral RNA, thereby inhibiting viral replication. Upon release from activated eosinophils, RNASE2 can signal through pattern recognition receptors such as Toll-like receptor 2 (TLR2) to activate dendritic cells and promote T-helper type 2 (Th2) immune responses. Elevated levels of RNASE2 are found in various inflammatory conditions, including asthma, allergic rhinitis, and parasitic infections, making it a key biomarker for eosinophil activation. Beyond its roles in immunity and inflammation, RNASE2 also exhibits neurotoxic activity, and has been implicated in wound healing and tissue remodeling processes.