Diagnostic efficacy of a simple radioimmunoassay test for fibrinogen/fibrin fragments containing the B beta 15-42 sequence.

A simple RIA method for B beta 15-42 RPs has been evaluated in our laboratory to investigate experimental and clinical fibrinolytic states. The assay utilizes bentonite precipitation to remove cross-reacting fibrinogen. Due to the heterogeneity in molecular weights of the B beta RPs, the results are expressed as nanograms per milliliter. The linear range of the assay is 2 to 40 ng/ml, with a capability of detecting up to 200 ng/ml. A special anticoagulant mixture (heparin or EDTA/aprotinin) is required for sample collection. Certain precautions in the care and handling of specimens are also necessary. Increased levels of B beta RPs were observed in the following conditions: malignancy (associated with increased release of tissue plasminogen activators), pancreatitis, liver diseases, pregnancy, and postexercise testing (associated with increased release of tissue plasminogen activators). Increased levels of B beta RPs were also found during thrombolytic therapy, anabolic steroid treatment, prothrombin complex concentrate therapy, blood component therapy, and low molecular weight heparin subcutaneous therapy (associated with an increase in tissue plasminogen activator release). Our studies suggest that B beta RPs are sensitive molecular markers of the endogenous activation of fibrinolytic system and may provide useful diagnostic information on a pathologic process that often remains undetectable by routine laboratory methods.