The monoclonal antibody that recognizes an epitope in the C-terminal region of the fibrinogen α-chain reacts with soluble fibrin and fibrin monomer generated by thrombin but not with those formed as plasmin degradation products

IntroductionThe presence of soluble fibrin (SF) provides evidence of thrombin activation in the blood; therefore, SF is a useful marker for diagnosing blood coagulation diseases such as disseminated intravascular coagulation (DIC). The antibody that specifically detects SF could be a useful tool for diagnosing thrombotic diseases.Materials and methodsBy using an acid-solubilized desAA-FM (fibrin monomer) as an immunogen, we developed a monoclonal antibody, namely J2-23, which specifically reacts with SF and FM. We examined the specificity of J2-23 by ELISA and immunoblotting and confirmed the reactivity of J2-23 with SF and FM by gel filtration.Results and conclusionsJ2-23 specifically reacted with SF, but not with fibrinogen or plasmic fibrinogen-derived Fbg-X, Fbg-Y, Fbg-E, and D; thrombin-treated Fbn-X, Fbn-Y, and Fbn-E; and plasmic cross-linked fibrin (DD, XDP). The epitope recognized by J2-23 was located within the Aα 502–521 region on the C-terminal of the fibrinogen α-chain. The reactivity of J2-23 disappeared following the action of the fibrinolytic enzyme plasmin. Furthermore, J2-23 reacted not only with SF but also with FM in plasma from DIC patients. This indicated that J2-23 specifically detected coagulation without reflecting the plasmin action. We demonstrated the potential of J2-23 as a useful antibody for detecting SF for diagnosing blood coagulation.