THE DEVELOPMENT OF AN ASSAY FOR HUMAN NEUTROPHIL LIPOCALIN (HNL) - TOBE USED AS A SPECIFIC MARKER OF NEUTROPHIL ACTIVITY IN-VIVO AND VITRO

Human neutrophil lipocalin (HNL) is a newly discovered protein from hu man neutrophil secretory granules. A double-antibody radioimmunoassay (RIA) was developed for the measurement of HNL in various body fluids and its high specificity was confirmed by the absence of cross-reactio n with other granulocyte granule proteins. The RIA measures HNL within the range of 4-256 mu g/l. The intra- and interassay coefficients of variation were less than 6% and 10%, respectively. When HNL was added to serum samples full recovery was obtained. Sera and plasma from 100 apparently healthy individuals revealed a mean level of 78.40 mu g/l ( range 37.95-190.87 mu g/l) in serum and a mean level of 50.65 mu g/l ( range 30.51-105.8 mu g/l) in EDTA-plasma. The distribution of HNL afte r gel filtration indicated that HNL exists mainly in two major forms, dimer and monomer. This, in addition to the excellent recovery, sugges ts that these major forms of HNL do not bind to compounds in serum or plasma that would interfere with the assay. The high specificity, sens itivity, reproducibility and accuracy of the present assay should faci litate the measurement of HNL in blood and other body fluids.