Enzyme-linked immunosorbent assay for the determination of blood coagulation factor XIII A-subunit in plasma and in cell lysates

A new one-step ELISA was developed for the determination of the concentrati on of blood coagulation factor XIII subunit A (FXIII-A) in plasma and in ce ll lysates. Monoclonal antibodies directed against different epitopes on FX III-A were used for the assay. The capture antibody was biotinylated on its carbohydrate moiety and the detection antibody was labelled with horseradi sh peroxidase. The antigen-antibody reaction was carried out in the well of a streptavidin-coated microplate. Complex formation with FXIII subunit B ( FXIII-B) and association to fibrinogen did not influence the accessibility of the antibodies to FXIII-A. The method could be performed within 2 h and demonstrated good reproducibility, recovery and sensitivity. Plasma samples could be assayed after storage at - 20 degreesC for at least 6 months. How ever, in the case of platelet lysates freezing and rethawing resulted in a significant loss of FXIII-A. FXIII-A concentrations measured in the plasma samples of healthy individuals and patients correlated well with the concen trations of complexed plasma FXIII (A(2)B(2)) and with the results of FXIII activity measurements. A reference range of 46-82 fg/platelet was establis hed for platelet FXIII-A. (C) 2001 Elsevier Science B.V. All rights reserve d.