SERUM MEASUREMENTS OF HUMAN NEUTROPHIL LIPOCALIN (HNL) DISCRIMINATE BETWEEN ACUTE BACTERIAL AND VIRAL-INFECTIONS

Human neutrophil lipocalin (HNL) is a recently identified protein from human neutrophil granules. The concentrations of HNL in the circulati on were measured, in a group of patients with acute infections, using a radioimmunoassay. The concentrations of HNL in patients infected by viruses and bacteria were 93.78+/-45.30 mu g 1(-1) (SD), 404.14 +/- 35 5.02 mu g 1(-1) (SD) in serum, and 47.81 +/- 18.18 mu g 1(-1) (SD), 14 5.46 +/- 194.32 mu g 1(-1) (SD) in plasma, respectively. The differenc es between the two patient groups were highly significant. There was a significant correlation between serum HNL and plasma HNL levels in ba cterial infections (r=0.73, p<0.0001). The HNL serum levels also corre lated with those of C-reactive protein(CRP) (r=0.59, p<0.0001). Determ ination of HNL in serum was more specific and sensitive than CRP in th e distinction between viral and bacterial infections. At a cut-off of 155 mu g 1(-1) (HNL in serum), the positive and negative predictive va lues for the diagnosis of bacterial infections were 92 and 96%, respec tively, which were superior to the optimal predictive values of CRP. T hus, the determination of HNL level is useful in the diagnosis of acut e bacterial infections.