A comparative evaluation of ELISAs for D-dimer and related fibrin(ogen) degradation products

This study was designed to (i) characterize two new monoclonal antibodies that react with neoepitopes on fibrin(ogen) fragments D-dimer and D1 and (ii) compare the specificity of these antibodies with that of two commercially available 'D-dimer' ELISAs [Dimertest EIA (American Diagnostica, Inc.) and Asserachrom D-Di (Diagnostica Stago)] and also with an ELISA for fibrinolytic fragments containing the E domain complexed with a D (or D-dimer) moiety [Fibrinostika FbDP (Organon Teknika)]. All assays were in a capture (sandwich) ELISA format. Fibrin(ogen) degradation products were isolated in high yield by a novel method involving hydrophobic interaction chromatography. The results disclosed considerable differences in sensitivity and specificity for purified fibrinolytic fragments among all five ELISAs. Although the diagnostic utility of monitoring plasma fibrinolytic fragments is not questioned, our results provide a rational basis for understanding why mAb-based ELISAs for these analytes are not well correlated. If, as our data suggest, the D-dimer ELISAs are not actually measuring the same analytes, then interpretation of studies that determine D-dimer concentrations with different methods will be problematic and standardization of D-dimer measurements across assays will be impossible.