A latex immunoassay of fibrin/fibrinogen degradation products in plasma using a monoclonal antibody.

We have developed a latex immunoassay using an anti D neo monoclonal antibody (F2C5) which recognizes an epitope present in fragment D but which is hidden in intact fibrinogen and in early fibrinogen degradation products. This technique was applied directly to plasma of both healthy donors and patients, and was shown to be very convenient for clinical investigation, especially in emergency cases for diagnosis of intravascular coagulation. The use of plasma samples instead of serum offers several advantages: it is not time consuming since blood clotting is not required; it avoids overestimation when fibrinogen cannot be totally clotted, and underestimation due to the binding of nonclottable fibrin degradation products to the clot during clotting in vitro. This monoclonal antibody, which reacts more with FbDP (expressed in fragment D) than with fragment D, does not allow fibrin and fibrinogen degradation products to be differentiated. However, this discrimination does not seem critical for its clinical use since the level of fragment D neo antigen remained within the normal range in 12 cases of spontaneous or venous occlusion-induced hyperfibrinolysis.