Effect of endotoxin on Erythrocyte Sedimentation Rate values

Endotoxin (lipopolysaccharide, LPS) is part of the outer wall of a Gram-negative bacterial cell. LPS is a powerful mediator that causes a number of pathophysiological changes such as inflammations, tissue destruction, respiratory distress, capillary damage, intravascular coagulation and hypotension. The effect of LPS on Erythrocyte Sedimentation Rate (ESR) determinations has not previously been investigated. We performed in vitro studies by mixing human citrated whole blood (CWB) with LPS at a concentration 5 ug/mL. The samples (n=11) and (n=5) were incubated at 37°C for 10 minutes. The samples (n=11) were then refrigerated for 24 hours and incubated at 37°C for 30 minutes. The samples (n=5) were incubated for 24 hours at 37°C. The samples were allowed to settle for one hour and the ESR determined. The results indicate LPS treated blood had a significant reduction (p<0.05) in ESR values compared to the controls.