DISCREPANCY BETWEEN LATEX AND ELISA D-DIMER VALUES IN SEPSIS MAY BE CAUSED BY HUMAN NEUTROPHIL ELASTASE

We have recently shown that D-dimers are degraded by human neutrophil elastase (HNE) in vitro, causing rapid decrease in the D-dimer levels measured by a Latex test, but not with an ELISA test employing the sam e monoclonal antibody against D-dimer. To see if such discrepant D-dim er concentrations occurred in patients with high HNE concentration, we examined 80 plasma samples from 8 patients with sepsis with a Latex a nd an ELISA test and calculated the ratio between the D-dimer values o btained with the two tests. Twenty healthy pregnant and twenty pre-ecl amptic patients, who are known to have raised D-dimer but low HNE conc entrations, were chosen as controls. HNE levels were estimated by dete rmining the HNE-alpha 1-proteinase inhibitor complex (HNE-A1PI) concen tration. HNE-A1PI concentration was increased in sepsis patients compa red with pre-eclamptic patients (p<0.0005) and healthy pregnant women (p<0.0005). In sepsis patients, the D-dimer results were skewed toward s lower ratios between Latex and ELISA values compared to pre-eclampti c patients (p=0.008) and healthy pregnant women (p=0.0001). In plasma samples from patients with the largest discrepancy between Latex and E LISA D-dimer values, Western blotting with immunostaining indicated de gradation of D-dimers to D-like fragments similar to those observed fo llowing degradation of cross-linked fibrin by HNE in vitro. We conclud e that in sepsis patients there is a marked discrepancy between Latex and ELISA D-dimer values that may be caused by HNE. In such patients L atex D-dimer assays may cause severe underestimation of fibrinolysis. (C) 1997 Elsevier Science Ltd.