Characterization of a murine monoclonal antibody that mimics heparin-induced thrombocytopenia antibodies

摘要: Antibodies to PF4/heparin can be demonstrated in almost all patients with heparin-induced thrombocytopenia/thrombosis (HIT/HITT) and some persons exposed heparin who do not have clinical manifestations. The role of anti-PF4/heparin antibodies the pathogenesis HIT/HITT has been difficult establish because found serum are generally polyclonal polyspecific. To circumvent this problem, we developed a murine monoclonal antibody (mAb) human (h) complexes. A IgG2bκ (designated KKO) was identified that bound specifically hPF4/heparin Maximal binding KKO complexes occurred at similar molar ratios PF4:heparin observed for antibodies. also hPF4 association other glycosaminoglycans. Platelet activation by required abrogated blockade FcγRIIA. In presence PF4, endothelial cells, but CHO cells lacking heparan sulfate proteoglycans. Variants PF4 complexed were recognized equally well sera. competes subset relatively spared mutations 3rd domain PF4. nucleotide predicted amino acid sequences RTO, anti-hPF4 mAb does require binding, revealed no obvious relationship either heavy- or light-chain immunoglobulin variable regions. These studies suggest recapitulates antigenic functional specificity may, therefore, provide insight into thrombocytopenia thrombosis affected persons.