DMBT1 (deleted in malignant brain tumors 1) is a multifunctional glycoprotein that serves as a critical component of mucosal innate immunity and host defense. The protein functions as a pattern recognition receptor, displaying broad calcium-dependent binding activity against both Gram-positive and Gram-negative bacteria, including Streptococcus mutans, through its scavenger receptor cysteine-rich (SRCR) domains 12. DMBT1 is secreted into various body fluids including saliva, bronchoalveolar fluid, and exosomes, where it acts as an antimicrobial agent and agglutinin 1. The protein exhibits structural polymorphism in its SRCR repeat regions, with different allelic variants showing distinct pathogen-binding specificities that are maintained by balancing selection 2. Beyond antimicrobial functions, DMBT1 promotes angiogenesis and tissue repair, as demonstrated by its role in diabetic wound healing when delivered via exosomes 3. In the respiratory system, DMBT1 regulates nitric oxide production in lung epithelial cells and is highly expressed in meconium aspiration syndrome 4. The protein also influences intestinal immunity, with IL-22 inducing DMBT1 expression across multiple intestinal cell types 5. Clinically, DMBT1 shows altered expression in various cancers and may serve as a biomarker, with salivary levels correlating with oral microbiome changes in cancer patients 6. Loss-of-function variants have been identified in familial glioma, suggesting tumor suppressor activity 7.