Pseudo-Factor-XI Deficiency: Effect of an Inhibitor of Factor XI Adsorption to Surface

Recently we have described a normal plasma activity that modulates contact activation by inhibiting adsorption of factor XI to activating surfaces. Here we report the first identified case in which a patient has abnormal clotting tests due to an excess of a similar activity. The patient’s plasma had...

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Veröffentlicht in:Blood 1981-03, Vol.57 (3), p.437-443
Hauptverfasser: Schiffman, Sandra, Margalit, Ruth, Rosove, Michael, Feinstein, Donald
Format: Artikel
Sprache:eng
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Zusammenfassung:Recently we have described a normal plasma activity that modulates contact activation by inhibiting adsorption of factor XI to activating surfaces. Here we report the first identified case in which a patient has abnormal clotting tests due to an excess of a similar activity. The patient’s plasma had a prolonged partial thromboplastin time and low apparent factor XI assay. His plasma prolonged the partial thromboplastin time of normal plasma and partially neutralized normal factor XI activity in vivo and in vitro. Analysis in dilute plasma revealed normal amounts of factor XI activity and antigen. Factor XI adsorption from plasma to activating surfaces was tested by adding a small amount of 125l-labeled purified factor XI to plasma, exposing the mixture to a glass tube or kaolin, and determining the amount of factor XI adsorbed to the surface. Whereas normal plasmas and plasmas deficient in factor XII, factor XI, or Fletcher factor yielded about 4% adsorption to glass, factor XI adsorption from patient’s plasma was less than 1%, indicating the presence of an adsorption inhibitor. This inhibitor did not affect factor XI activation or the activity of preformed factor Xla. It was not adsorbed by Al(OH)3 and was present in serum and the macroglobulin peak on gel filtration of the plasma through Sephadex G-200. The patient’s history does not allow a definitive conclusion as to whether this inhibitor was associated with abnormal bleeding.
ISSN:0006-4971
1528-0020
DOI:10.1182/blood.V57.3.437.437