Description
Rabbit Bactericidal Permeability-Increasing Protein (BPI) is an antimicrobial and endotoxin-neutralizing molecule that is abundant in the granules of neutrophils (a type of white blood cell). It plays a crucial role in the immune system by killing Gram-negative bacteria and neutralizing their endotoxins. BPI is composed of two distinct functional domains: an amino-terminal domain responsible for antimicrobial and anti-endotoxin activities, and a carboxyl-terminal domain that contributes to opsonic activity. This protein is part of a conserved family of lipid-binding proteins and is essential for the host defense against pathogens. In rabbits, BPI was originally isolated from the primary granules of polymorphonuclear leukocytes (PMNs) and has been shown to have in vitro antimicrobial activity. Its ability to bind to the lipid A component of lipopolysaccharide (LPS) from the outer envelope of Gram-negative bacteria makes it a key player in the innate immune response