Factor XIII of blood coagulation (FXIII), a protransglutaminase, is of tetrameric structure (Aï). With the exception of extremely rare B subunit deficiency, in the plasma all A subunits are complexed while the B subunits are in excess of A subunits. A subunit deficiencies result in severe bleeding disorder which frequently needs life-long supplementation therapy. In normal conditions relatively low concentration (1-5%) of FXIII is sufficient to maintain haemostasis and supplementation therapy usually aims to bring FXIII level into this range. A number of homozygous patients have some residual (below 1 %) FXIII in their plasma which might be related to the severity of bleeding diathesis. The presently available methods are either too cumbersome or not sensitive enough to measure low FXIII levels accurately. We developed a highly sensitive new sandwich ELISA for assaying plasma FXIII. The assay uses monoclonal antibodies against FXIII subunits and detects exclusively the complex tetrameric (A2B2) plasma protein. It is a one step ELISA, can be performed within 2 hours and shows an excellent reproducibility (within batch reproducibility in the normal range is CV 2.0%, and CV 3.3% even at low plasma concentrations, the day to day variations are 6.0% and 8.7%, respectively). The assay is linear up-to 10 ng/ml FXIII. Its sensitivity allows the highly reproducible determination of plasma FXIII even at concentration as low as 0.1% of average normal. Plasma samples not measured immediately can be stored at -20 °C, freezing and re-thawing does not affect the results. The assay can be used for measuring FXIII level in patients with inherited and acquired FXIII deficiencies, and allows reliable monitoring of FXIII supplementation.
|Number of pages||1|
|Journal||Fibrinolysis and Proteolysis|
|Issue number||SUPPL. 1|
|Publication status||Published - Dec 1 1998|
ASJC Scopus subject areas