Diagnostic Relevance of Procalcitonin, IL-6, and sICAM-1 in the Prediction of Infected Necrosis in Acute Pancreatitis

Abstract

Infected pancreatic necrosis (IPN) is an absolute indication for surgical intervention, therefore an early and accurate laboratory diagnosis is necessary to confirm the infection. The aim of the study was to analyze the clinical value of procalcitonin (PCT) for the prediction of infected necrosis, in comparison with interleukin-6 (IL-6) and sICAM 1. A total of 30 patients were investigated; 10 patients with sterile pancreatic necrosis (SPN), 10 with IPN, and 10 with sepsis of different origin. The concentrations of PCT in the patients' sera were measured by immunoluminometric assay (BRAHMS Diagnostica, Berlin, Germany, PCT Lumitest), the IL-6 concentrations by bioassay, applying the B-9 cell line, and the sICAM-1 levels by enzyme-linked immunosorbent assay (ELISA) (R&D). PCT was determined in cell lysates by ECL Western blot. PCT was found in relatively high concentrations (8.5 +/- 4.8 ng/mL) only in patients with infected pancreatic necrosis, and in patients with sepsis of different origin ( 15 +/- 5.4 ng/mL). Positive values (> 1 ng/mL) preceded positive bacterial results from either blood or surgical samples. None of the serum samples of patients with SPN exhibited PCT concentrations higher than 1.2 ng/mL. In contrast, IL-6 and sICAM-1 were overproduced in both types (infected and sterile) of pancreatic necrosis, and their levels remained elevated for several days even after surgical elimination of the infected focus (widespread necrosectomy and continuous lavage). Sensitivity, specificity, and positive predictive values for discriminating IPN from SPN was 90, 100, and 100% for PCT (p < 0.0001); 100, 20, and 55% for IL-6 (p 0.474 n.s.) and 90, 10, and 50% for sICAM-1 (p 1.000 n.s.). Immunoblotting revealed no PCT in patients' leukocytes, or in human endothelial cell lines. Elevated serum IL-6 and sICAM-1 levels are characteristic in systemic inflammatory response syndrome (SIRS) of either infectious or noninfectious origin. In contrast, the PCT level is an accurate, readily available parameter that allows the discrimination of IPN, and is a helpful marker facilitating a decision concerning surgical intervention.