Time-resolved fluoroimmunoassay for bactericidal/permeability-increasing protein

H Peuravuori,A B Jokilammi-Siltanen,T J Nevalainen,J.-O Häggblom

doi:10.1155/s0962935196000087

Abstract

Bactericidal/permeability-increasing protein (BPI) is a cationic antimicrobial protein produced by polymorphonuclear leukocytes, that specifically interacts with and kills Gram-negative bacteria. BPl competes with lipopolysaccharide-binding protein (LBP) secreted by liver cells into blood plasma for binding to lipopolysaccharide (LPS) and thus reduces the proinflammatory effects of LPS. We have developed a time-resolved fluoroimmunoassay for BPI and measured the concentration of BPI in human serum and plasma samples. The assay is based on a rabbit antibody against recombinant BPI. This antibody specifically adheres to polymorphonuclear leukocytes in immunostained human tissues. The difference in the serum concentration of BPI between unselected hospitalized patients with and without an infection was statistically significant. The mean concentration of BPI in serum samples was 28.3 μg/l (range 1.64–132, S.D. 26.8, n = 83). In contrast, there was no difference between the two groups in the BPI levels in plasma samples. For all individuals tested, BPI levels were consistently higher in plasma samples compared to the matched serum samples. The mean concentration of BPI in plasma samples was 52.3 μg/l (range 0.9–403, S.D. 60.6, n = 90). There was a positive correlation between the concentration of BPI and the white blood cell count as well as between the BPI concentration and C-reactive protein (CRP) in serum samples. In conclusion, the present study demonstrates that BPI can be quantified reliably by time-resolved fluoroimmunoassay in human serum samples.

Highlights

The bactericidal/permeability-increasing protein (BPI) is a cationic antimicrobial protein produced by polymorphonuclear leukocytes
The present paper describes a new immunoassay using time-resolved fluorescence technology for measuring the concentration of BPI
An enzyme immunoassay (ELISA) for determining the concentration of BPI was recently developed by White and coworkers.[28]

Summary

Introduction

The bactericidal/permeability-increasing protein (BPI) is a cationic antimicrobial protein produced by polymorphonuclear leukocytes. BPI interacts with and kills Gram-negative bacteria. BPI binds to the lipopolysaccharide (LPS) component of the outer membrane of Gram-negative bacteria, increases membrane permeability to hydrophobic substances and causes irreversible loss of bacterial cell homeostasis.. BPI competes with lipopolysaccharide-binding protein (LBP) secreted by liver cells into the blood plasma for binding to LPS.7-m In this way BPI reduces the proinflammatory effects of gps. Because there is potential anti-infectious therapeutic use for recombinant BPI, a sensitive assay which can measure BPI in body fluids is (C) 1996 Rapid Science Publishers needed. The purpose of the present study was to develop a time-resolved fluoroimmunoassay (TRFIA) for the measurement of the concentration of BPI in human serum

Objectives

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Conclusion