Eosinophil major basic protein (MBP) (MBP)

Eosinophil major basic protein (MBP), encoded by the PRG2 gene, is a highly basic, 14 kDa cytotoxic protein primarily stored in the crystalline core of eosinophil granules (UniProt P13727). It is synthesized as a pro-protein (proMBP) containing an acidic pro-domain that neutralizes the toxicity of the mature MBP during intracellular transport; this pro-form also circulates in pregnancy as a complex with pregnancy-associated plasma protein A (PAPP-A) (NCBI Gene 5553). MBP's primary biological function is host defense against helminthic parasites, achieved through the disruption of parasite membranes via its high cationic charge density (PubMed 2455431). In pathological states, the dysregulated release of MBP is a major driver of tissue damage in asthma, eosinophilic esophagitis, and atopic dermatitis, where it causes epithelial shedding and triggers mast cell degranulation (PubMed 15546393). While not a traditional receptor target, MBP is therapeutically relevant as its toxic effects can be neutralized by polyanionic compounds like heparin (PubMed 11738510). Monitoring MBP levels in biological fluids serves as a valuable biomarker for assessing the extent of eosinophilic inflammation and the efficacy of anti-eosinophil therapies.

Other names

Proteoglycan 2PRG2Eosinophil-derived major basic proteinBone marrow proteoglycanBMPGNatural killer cell activator

Neutralization of the protein's high cationic charge to prevent membrane disruption and tissue damage.