Bactericidal/permeability increasing protein (BPI) is a 456 residue (~50kDa) protein which is part of the innate immune system.
Distribution and function
BPI was initially identified in neutrophils
, but is found in other tissues
including the epithelial
lining of mucus membranes
It is an endogenous antibiotic protein with potent killing activity against some bacteria
). It binds to compounds called lipopolysaccharides
produced by Gram-negative bacteria. Lipolysaccharides are potent activators of the immune system
, however BPI at certain concentrations can prevent this activation.
BPI was discovered by Jerrold Weiss and Peter Elsbach at New York University Medical School.
Because lipopolysaccharides are potent inflammatory
agents, and the action of antibiotics can result in the the release of these compounds, the binding capacity of BPI was explored as a possible means of reducing injury. Xoma Ltd.
developed a recombinant
25kDa portion of the BPI molecule called rBPI21
, NEUPREX or opebecan. It was given as trial has been found to have decrease the mortality in Gram-negative bacterial induced sepsis. Studies suggest that its binding activity is not the means by which it mediates its protective effect. Studies show biological effects with Gram-positive bacteria
and even in infection by the protozoan
, Toxoplasma gondii