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Effect of platelet phospholipid exposure on activated protein C resistance: implications for thrombophilia screening
Author(s) -
Luddington Roger,
Brown Karen,
Baglin Trevor
Publication year - 1996
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 - 10.1046/j.1365-2141.1996.391924.x
Subject(s) - platelet , factor v , activated protein c resistance , platelet activation , protein c , medicine , protein s , andrology , chemistry , endocrinology , immunology , biology , factor v leiden , thrombosis , venous thrombosis
The effect of platelet contamination and freeze‐thawing on the activated protein C sensitivity ratio (APCsr) was determined. With increasing platelet count there was a progressive reduction in the ratio. Filtration of samples through a 0.2 μm filter before or after freeze‐thawing abolished the development of resistance to the addition of activated protein C indicating that the phenomenon is due to the presence of a particulate factor. Contamination of normal plasma with platelets from a patient with homozygous factor V (FV) deficiency was also associated with the same development of resistance to activated protein C, indicating that the phenomenon was not due to exposure of platelet‐derived factor V that might be inaccessible to APC. 82% (96/117) of FVQ506 and 32% (138/430) of FV R506 individuals had APC resistance on analysis of unfiltered plasma. However, 85% (42/50) of FVQ506 individuals had APC resistance on analysis of filtered plasma, whilst only 1/50 FV R506 individuals had APC resistance after filtration. For the purpose of identifying individuals at increased risk of venous thromboembolism due to the presence of the FVQ506 and associated APC resistance a PCR‐based genotypic analysis is recommended.