Comparison of whole blood interleukin-8 and plasma interleukin-8 as a predictor for sepsis in postoperative patients

Objective: Interleukin-8 (IL-8, also known as neutrophil-activating peptide 1, NAP1 and CXCL8, CXC chemokine ligand 8) is recognized as a potent effector of neutrophil functions. IL-8 is a major response factor following NfkB activation by cytokines or lipopolysaccharide and several different cell types T lymphocytes, monocytes, epithelial and endothelial cells secrete this polypeptide. IL-8 is not to be determined at significant concentrations in plasma due to its receptor binding but may play a major role in tissues. The prediction of sepsis is a major and current field of research in the treatment of surgical patients. The aim of this study was to compare the determination of IL-8 in whole blood cell lysates (whole blood IL-8) and in plasma for the prediction of sepsis in postoperative intensive care. Design: Whole blood IL-8, IL-8 in plasma, and CRP were measured in the daily routine monitoring of 84 patients in a surgical intensive care unit. Sepsis was defined by the criteria of the Society of Critical Care Medicine (SCCM). For comparison the APACHE II score (APACHE = Acute Physiology and Chronic Health Evaluation) was calculated. The diagnostic value of the three tests was compared by receiver operating characteristic (ROC) curves. Results: Whole blood IL-8 showed higher areas under the curve (AUC) than IL-8 in plasma and CRP. The ROC curves for the APACHE II scores gave similar results. Conclusions: Sepsis is a complex disease and is induced by systemic infection of patients suffering from systemic inflammatory response syndromes (SIRS). Therefore, the identification of infection or the host response to infection is of crucial importance. The prediction of an individual marker or interleukin or its binding to surface proteins is not necessarily indicative for sepsis. In cases with unequivocally identified bacterial infections, the current results suggest that whole blood IL-8 may have a similar diagnostic accuracy as plasma levels. Of note, this technique needs less blood and is not being affected by hemolysis.