Endotoxin binding to platelets in blood from patients with a sepsis syndrome

Abstract

Endotoxin, the lipopolysaccharide cell wall constituent of Gram-negative bacteria, produces symptoms of the Gram-negative sepsis syndrome. By measuring endotoxin in blood from septic patients it may be possible to select a subpopulation of patients in which mortality can be prevented by treatment with anti-endotoxin antibodies. We evaluated the performance of an endotoxin-free blood-collection tube. Within-run and between-run CVs of our endotoxin assay were 4-18% and 8-20%, respectively. In endotoxin-positive samples (LPS > or = 6 ng/L), the concentration of endotoxin in platelet-rich plasma was significantly higher (P < 0.001) than in platelet-poor plasma. Apparent binding of endotoxin to platelets ranged from 0% to 92%. The correlation between the apparent percentage binding of LPS to platelets and the platelet count in platelet-rich plasma is linear and positive, but LPS is not bound solely to platelets. We conclude that endotoxin must be measured in platelet-rich plasma.

P-selectin binds to bacterial lipopolysaccharide

“…Further work is required to determine whether the thrombin-induced expression of P-selectin on platelets or endothelial cells, followed by an increased binding of LPS to these cells, could have a significant role in the pathophysiology of organ failure in septic shock. It has been reported that in blood from sepsis patients most of the LPS is associated with activated platelets [4]. Our results indicate that LPS binding to activated platelets takes place via P-selectin and one function of LPS binding to platelets could be to remove soluble LPS from blood.…”

“…Activated platelets play a major role in DIC. Rat models of septic shock and LPS-induced liver injury have shown that an accumulation of platelets, followed by neutrophil infiltration, contribute to the manifestation of LPSinduced tissue damage [2][3][4]. Several lines of evidence indicate that thrombin is required for LPS-mediated organ failure.…”

“…This damage is independent of clot formation [2,3]. LPS has been shown to be associated with platelets isolated from patients with sepsis [4]. Platelets bind to the lipid A portion of LPS [5][6][7][8].…”

Plasma endotoxin concentration in horses: a methods study

“…Because both humans and horses are exquisitely susceptible to endotoxin, there has long been a strong desire to quantify systemic endotoxemia in an effort to better understand its role in these disease processes and as a predictor of mortality. However, measurement of endotoxin in the systemic circulation has been complicated by the fact that endotoxin binds to platelets, and RBCs interfere with the commonly used chromogenic Limulus amebocyte lysate assay 5–7 Consequently, the platelet‐rich plasma (PRP) fraction of whole blood (WB) is the desirable sample fraction needed for an accurate determination of systemic endotoxin. In addition to platelet‐binding, the anticoagulant used can substantially influence results.…”

“…In addition to platelet‐binding, the anticoagulant used can substantially influence results. Specifically, heparin, the anticoagulant commonly used in equine plasma‐based clinical pathologic research, causes platelet activation and aggregation, modulates activated polymorphonuclear leukocyte‐induced platelet activation, and binds to both cell types, as does endotoxin 5,8–10 . Thus, heparin‐medi‐ated actions may directly or indirectly affect endotoxin quantification 11 .…”