Measurement of soluble fibrin monomer-fibrinogen complex in plasmas derived from patients with various underlying clinical situations.

We previously reported a monoclonal antibody named IF-43 that specifically recognizes thrombin-modified fibrinogen (desAA- and desAABB- fibrin monomer) bound with fibrinogen or other D(1) domain-containing plasmic fragments such as fragments X,Y, and D(1), but not intact fibrinogen or cross-linked fibrin degradation products (XDP). Here, we tentatively named such complexes, soluble fibrin monomer (FM) -fibrinogen complex. By utilizing IF-43, we have developed a kit to measure soluble FM-fibrinogen complex and compared the profiles with those of two established molecular markers for thrombo-embolic disorders: i.e. the thrombin-antithrombin complex (TAT) and the D-dimer in plasma of patients who underwent surgery without any thrombo-embolic complications. The result indicated that soluble FM-fibrinogen complex is a distinct entity from the two established molecular markers. We have also attempted to observe their profiles in patients with the disseminated intravascular coagulation syndrome (DIC). Although the pro-files of soluble FM-fibrinogen complex in individual patients appeared to vary from one patient to the other, the plasma level of soluble FM-fibrinogen complex was found to be increased at the initial phase of disseminated intravascular coagulation syndrome. Thus, the soluble FM-fibrinogen complex may serve as an independent molecular marker for the detection of thrombin generation and the diagnosis of thrombosis. The soluble FM-fibrinogen complex may also serve as a risk factor for thrombosis, because it may precipitate as insoluble complexes beyond its threshold in plasma, or when it is modified by thrombin.