Rapid detection of cross-linked fibrin degradation products in plasma using monoclonal antibody-coated latex particles.

Conformational and structural changes on conversion of fibrinogen to fibrin and its cross-linking by Factor XIIIa lead to the development of new antigenic determinants that permit differentiation between their plasminolytic cleavage products. A monoclonal antibody (DD-3B6/22) that is specific for cross-linked fibrin derivatives containing the D dimer configuration has been used in developing a latex agglutination procedure that can detect fibrin degradation products in either plasma or serum. Fibrinogen or its degradation products do not cross-react with this antibody. Results were calibrated with an enzyme immunoassay, which used a purified D dimer standard. Plasmas from 40 normal subjects, all having D dimer levels below 250 ng/mL measured by enzyme immunoassay, were all negative by latex assay. In contrast, positive latex agglutination titers were obtained with 87 of 88 patients with demonstrated deep venous thrombosis, pulmonary embolism, or disseminated intravascular coagulation. Compared to enzyme immunoassay, latex agglutination assay is less sensitive, but this latex procedure provides a rapid and less elaborate test for elevated levels of cross-linked fibrin degradation products in patients with thrombosis. Plasma assays for fibrin degradation products are preferable to those using serum.