Influence of factor XIIIa activity on human whole blood clot lysis in vitro
Jansen, J.W.; Haverkate, F.; Koopman, J.; Nieuwenhuis, H.K.; Kluft, C.; Boschman, T.A.
Thrombosis and Haemostasis 57(2): 171-175
1987
ISSN/ISBN: 0340-6245 PMID: 2440124 Document Number: 289114
We studied the influence of Factor XIIIa (F XIIIa) activity on the lysis rate of fresh whole human blood clots, without using anticoagulants. Clotting was induced by exogenous thrombin, lysis by tissue-type Plasminogen Activator (t-PA) added before clotting. After various periods of time, lysis rates were determined by measuring the radioactivity in the supernatant of the clot originating from 125I-Fibrinogen added before clotting. Lysis rates were determined in the presence of endogenous F XIIIa and compared with those obtained after specific inhibition of F XIIIa activity. We used an IgG fraction of an antiserum quenching the f XIIIa activity. Addition of increasing amounts of the antibodies to normal blood resulted in a dramatic increase in clot lysis rate, concomitant with loss of F XIII activity. Lysis of blood clot from a patient with a congenital, homozygous, functional .alpha.2-Antiplasmin (.alpha.2-AP) deficiency (.alpha.2-AP-Enschede) was not or slightly increased by the anti F XIII antibodies indicating that fibrin-fibrin crosslinking per se does not contribute essentially to resistance of the blood clot against fibrinolysis. Both active .alpha.2-AP and F XIII a are required for the major part of the F XIII-dependent resistance of whole blood clots against lysis.