A neoantigenic determinant in coiled coil region of human fibrin β-chain

IntroductionThe transformation of fibrinogen into fibrin by thrombin exposes neoantigenic determinants that are buried in fibrinogen. Fibrin-specific monoclonal antibodies (mAbs) to these neoantigenic determinants, which don't react with fibrinogen, can be obtained. The aim of our investigation was to obtain fibrin-specific mAbs, to study their influence on fibrin polymerization and to use them for quantification of soluble fibrin in human blood plasma.Materials and methodsHuman fibrin desAABB in 2 M urea was used as an antigen. Standard hybridoma technique was used for production of mAbs. Turbidity analysis and transmission electron microscopy were used to study the effect of mAbs and their Fab-fragment on fibrin polymerization. The localization of epitope for mAb in fibrin molecule was determined using ELISA and immunoblot analysis with fibrinogen, fibrin desAA, fibrin desAABB and various fibrin(ogen) fragments.ResultsA mAb FnI-3C has been obtained that doesn't bind to fibrinogen and reacts with fibrin desAA and fibrin desAABB with KD value of 9.76·10- 10 M. The epitope for this mAb proved to be localized in the fibrin fragment Bβ118-134. MAb FnI-3C and its Fab retarded specifically the stage of fibrin protofibril lateral association.ConclusionsA fibrin-specific mAb FnI-3C has been obtained to fibrin fragment Bβ118-134 which may be a contact site taking a part in protofibril lateral association. MAb FnI-3C was used as a “catch”-one in double-sandwich ELISA for soluble fibrin quantification in human blood plasma.