The MASP2 (Mannose-Associated Serine Protease 2) antibody targets a key enzyme in the lectin pathway of the complement system, a critical component of innate immunity. MASP2 is produced primarily in the liver and circulates in blood as part of multimolecular complexes with pattern recognition molecules like MBL (mannose-binding lectin), ficolins, or collectins. When these molecules bind to pathogen-associated molecular patterns (e.g., carbohydrates on microbial surfaces), MASP2 is autoactivated, cleaving complement proteins C4 and C2 to form the C3 convertase (C4b2a), which drives downstream complement activation, inflammation, and pathogen clearance.
MASP2 antibodies are used in research to study its role in immune responses and diseases linked to lectin pathway dysregulation. Overactivation of MASP2 is implicated in conditions like atypical hemolytic uremic syndrome (aHUS), ischemia-reperfusion injury, and certain autoimmune disorders. Conversely, genetic MASP2 deficiencies increase susceptibility to infections. Therapeutic anti-MASP2 antibodies (e.g., narsoplimab) are under investigation to inhibit excessive complement activation in diseases such as transplant-associated thrombotic microangiopathy. These antibodies typically block enzymatic activity or disrupt interactions with partner proteins.
As a serine protease with a unique structure (CUB1-EGF-CUB2-CCP1-CCP2-SP domains), MASP2 is also a biomarker for lectin pathway activity. Its study aids in understanding complement-related pathologies and developing targeted immunotherapies.