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Factor XI and Platelets: Evidence that Platelets Contain only Minimal Factor XI Activity and Antigen
Author(s) -
Schiffman Sandra,
Rimon Abraham,
Rapaport Samuel I.
Publication year - 1977
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1977.tb00603.x
Subject(s) - platelet , chemistry , clotting factor , medicine , endocrinology , activator (genetics) , platelet factor 4 , biochemistry , biology , receptor
Factor‐XI activity of platelets has been studied in platelet‐rich plasmas and isolated platelet suspensions. Fresh platelets in both environments had little or no measurable factor‐XI activity. Frozen and thawed platelet‐rich normal plasma had markedly elevated apparent factor‐XI activity and factor‐IX activity as compared to platelet‐poor plasma. Frozen and thawed platelet‐rich and platelet‐poor normal plasmas had equivalent factor‐XI antigen. Platelets isolated from normal blood and from factor‐XI deficient blood had the same small amounts of apparent factor‐XI activity, which increased slightly on freezing and thawing. The data indicates that minimal factor XI is associated with the platelet. The markedly elevated apparent factor‐XI activity of frozen and thawed platelet‐rich plasma is shown to reflect the interaction of a platelet activator with plasma clotting factors to produce a later activated‐clotting‐intermediate.