Background: Fibrin monomer (FM) and its complex (sFC) exist at high concentrations in hypercoagulable state blood. Two novel immunoassays for sFC (SF and FMC) using specific monoclonal antibodies (IF-43 and F405) were recently developed.
Methods: We measured the concentrations of thrombotic markers in 103 patients with DIC and thrombotic disorders.
Results: We found that the concentration of FMC was approximately 3.35-fold greater than that of SF. In patients with a high FMC/SF ratio, FDP and D dimer concentrations were increased, suggesting that the discrepancy in sFC concentrations was caused by fibrinolytic activity. Further, plasma samples from those patients were found to contain the X- and Y-fragments of FM in addition to FM and sFC in a Western blotting assay using F405, which binds with those fragments. In an in vitro study, FM formed from pooled plasma containing EDTA was degraded to the X- and Y-fragments of FM by fibrinolytic activity, and we termed those FM degradation products (FMDP).
Conclusion: Determination of FMDP is important for diagnosis of thrombogenic conditions associated with fibrinolysis, such as in patients with DIC, and it may serve as a useful marker for hypercoagulable states with accelerated fibrinolysis.