Summary
An enzyme-linked immunosorbent assay for fragment D-dimer was developed with the use of two monoclonal antibodies directed against specific non-overlapping antigenic determinants, present in fragment D-dimer of crosslinked fibrin but not in fragment D of non crosslinked fibrin or of fibrinogen, The lower limit of sensitivity of the assay when applied to human plasma, is 25 ng/ml. Concentration of fragment D-dimer in plasma from healthy individuals was 177 ,± 83 ng/ml (mean ± SD). In plasma of 11 out of 12 patients with phlebographically confirmed acute deep vein thrombosis, fragment D-dimer levels were significantly increased. Fragment D-dimer was not increased in 9 out of 10 patients with recurrent idiopathic deep vein thrombosis during clinically silent episodes.
Total t-PA antigen and free t-PA antigen concentrations were measured using previously developed ELISAs. Nine of the 12 patients with acute deep vein thrombosis showed a significant increase of total t-PA antigen (from 8.6 ± 6.9 ng/ml to 21 ± 16 ng/ml) after venous occlusion but in 3 of these free t-PA remained undetectable. Five of the 10 patients with recurrent deep vein thrombosis responded to venous occlusion with a significant increase of total t-PA antigen (from 6.7±3.2 ng/ml to 14 ± 7.9 ng/ml) but, in all patients, free t-PA antigen remained undetectable.
It is concluded that the combined assays of total and free t-PA antigen and of fragment D-dimer may be useful for the evaluation of the dynamics of the fibrinolytic system in physiological and pathological conditions.
Keywords
Fibrinolysis - D-dimer - Enzyme immunoassay - Deep vein thrombosis - Fibrinolytic response
