New D-dimer monoclonal antibodies (DD189 and DD255) allow for development of an improved immunoassay to detect D-dimer.
Elevated levels of D-dimer are found in the blood of patients with pulmonary embolism, deep vein thrombosis and atherosclerosis. D-dimer diagnostic tests are widely used to exclude the diagnosis of deep vein thrombosis. In addition, increased amount of D-dimer in blood is believed to be a reliable marker of pathological coagulation that underlies the pathogenesis of most cardiovascular diseases.
For the accurate determination of D-dimer, assays must not detect fibrinogen nor its degradation products (D-monomer). Here at Advanced ImmunoChemical offer two new monoclonal antibodies can be used to develop a one-step immunoassay equally specific for fibrin degradation products (FDP) and D-dimer. In addition, we offer D-dimer produced from clotted fibrinogen by means of plasmin digestion for standardization.
Why develop an assay with equal specificity to FDP and D-dimer?
Patient plasma contains a wide variety of FDP of different sizes along with D-dimer itself. All of these products possess the “D-dimer antigen epitope”. Therefore, antibodies specific to D-dimer also recognize FDP. However, there is a great variance between the results obtained by different assays. This can be explained by differences in antibody specificities; some antibodies and antibody pairs recognize D-dimer better than FDP and vice versa. So far all standardization and harmonization attempts have not resulted in satisfying results and this is a continuous cause of problems in daily practice.
The ratio of FDP and D-dimer in blood is not constant but varies from patient to patient. An assay which equally detects all fibrin degradation products including D-dimer will decrease bias in quantitative detection of all these different degradation products.
D-dimer and high molecular weight fibrin degradation products
D-dimer is the smallest degradation product resulting from fibrinolysis. In fibrinolysis, fibrin clots are digested by plasmin, and fibrin degradation products (FDP) of various sizes are released into the bloodstream (Fig. 1).
For an accurate determination of D-dimer and the varying range of high molecular weight FDPs, the assay should detect FDPs and D-dimer with equal specificity.
Kogan AE, et al. (2015) Monoclonal antibodies with equal specificity to D-dimer and high-molecular-weight fibrin degradation products. Blood Coagul. Fibrinolysis, 2015 Dec 11. [Epub ahead of print] PubMed PMID: 26656897.
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Best regards, Anne Tolles, M.Sc./President