The importance of antibody specificity in measuring cross-linked fibrin degradation products by ELISA.
We and others have previously shown that plasma concentrations of XL-FDPs are accurately characterized with an enzyme-linked immunosorbent assay (ELISA) based on the monoclonal antibody DD-3B6/22, which is specific for D-dimer, and a pan-specific tag antibody (DD-4D2/182) in patients with thrombotic disorders. However, in patients treated with fibrinolytic agents, increases in non-cross-linked fibrin(ogen) degradation products are detected by the pan-specific tag antibody due to formation of complexes between non-cross-linked derivatives and XL-FDPs. Assays based on the use of fibrin degradation product-specific tag antibodies appear to be more specific, but whether they would be clinically more informative is unclear. Accordingly, in the current study we measured concentrations of XL-FDPs with two ELISAs; one based on the pan-specific tag antibody (DD-4D2/182) and another based on a fibrin degradation product-specific tag antibody (DD-1D2/48) in patients treated with three well-characterized thrombolytic regimens: one associated with minimal fibrinogenolysis (100 mg tissue-type plasminogen activator [t-PA]) over 3 h), moderate fibrinogenolysis (100 mg t-PA over 90 min), and one with marked fibrinogenolysis (1.5 MU streptokinase [SK]). In patients treated with t-PA, increases in XL-FDPs were closely correlated with fibrinogenolysis, as characterized by increases in the concentration of the Bbeta1-42 peptide, when measured with the pan-specific tag ELISA (r = 0.7), but not when measured with the fibrin degradation product-specific tag assay (r = 0.2). In patients treated with SK, concentrations of XL-FDPs were significantly higher (> 2000 ng/ml) with the pan-specific tag ELISA compared with the fibrin degradation product-specific tag ELISA (< 1000 ng/ml) 1, 2 and 8 h after start of the infusion (P < 0.01). Concentrations of XL-FDPs were also higher in patients treated with SK compared with t-PA when measured with the pan-specific tag ELISA, but lower with SK with the fibrin-specific ELISA (P < 0.01). The value of measurement of XL-FDPs in patients treated with fibrinolytic agents will need to be reappraised with the use of fibrin degradation product-specific assays, which appear to provide more accurate information on the kinetics of cross-linked fibrin lysis in patients treated with t-PA or SK.
Eisenberg
P R
PR
Washington University School of Medicine, St. Louis, MO 63110, USA. eisenber@im.wustl.edu
Rylatt
D B
DB
Rusticali
F
F
Ferrini
D
D
Ottani
F
F
Galvani
M
M
D000918:Antibody Specificity; D004797:Enzyme-Linked Immunosorbent Assay; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis* / Q000276:immunology; D005342:Fibrinolysis; D006801:Humans; D009203:Myocardial Infarction / Q000097:blood / Q000188:drug therapy; D013300:Streptokinase / Q000627:therapeutic use; D010959:Tissue Plasminogen Activator / Q000627:therapeutic use
D005338:Fibrin Fibrinogen Degradation Products; D013300:Streptokinase; D010959:Tissue Plasminogen Activator