ENDOTOXIN BINDING TO PLATELETS IN BLOOD FROM PATIENTS WITH A SEPSIS SYNDROME

Endotoxin, the lipopolysaccharide cell wall constituent of Gram-negati ve bacteria, produces symptoms of the Gram-negative sepsis syndrome. B y measuring endotoxin in blood from septic patients it may be possible to select a subpopulation of patients in which mortality can be preve nted by treatment with anti-endotoxin antibodies. We evaluated the per formance of an endotoxin-free blood-collection tube. Within-run and be tween-run CVs of our endotoxin assay were 4-18% and 8-20%, respectivel y. In endotoxin-positive samples (LPS greater than or equal to 6 ng/L) , the concentration of endotoxin in platelet-rich plasma was significa ntly higher (P <0.001) than in platelet-poor plasma. Apparent binding of endotoxin to platelets ranged from O% to 92%. The correlation betwe en the apparent percentage binding of LPS to platelets and the platele t count in platelet-rich plasma is linear and positive, but LPS is not bound solely to platelets. We conclude that endotoxin must be measure d in platelet-rich plasma.