title: Standardization of activated protein C resistance testing: effect of residual platelets in frozen plasmas assessed by commercial and home-made methods.
abstract: We investigated 42 plasmas prepared at different centrifugation speeds with three activated protein C (APC) resistance methods. The APC ratio for fresh platelet-poor plasma declined significantly after freezing and thawing. This effect was more evident with the original method (average reduction 11.3%) than with either the home-made (3.8%) or the modified method (3.2%). No significant decrease in the APC ratio was observed after freezing and thawing of platelet-free plasmas from the same patients. When frozen platelet-poor plasma was centrifuged at high speed after thawing and before testing, there was no significant decrease in the APC ratio, in comparison with fresh platelet-poor plasma using the home-made and modified methods.
authors.affiliation: Angelo Bianchi Bonomi Haemophilia and Thrombosis Centre, Department of Internal Medicine, University and IRCCS Maggiore Hospital, Milan, Italy. armando.tripodi@unimi.it
authors.forename: Armando
authors.initials: A
authors.lastname: Tripodi
authors.forename: Carla
authors.initials: C
authors.lastname: Valsecchi
authors.forename: Veena
authors.initials: V
authors.lastname: Chantarangkul
authors.forename: Tullia
authors.initials: T
authors.lastname: Battaglioli
authors.forename: Pier Mannuccio
authors.initials: PM
authors.lastname: Mannucci
mesh_terms: D020016:Activated Protein C Resistance / Q000175:diagnosis*; D001781:Blood Component Removal; D001792:Blood Platelets; D002498:Centrifugation; D005165:Factor V / Q000235:genetics; D006579:Heterozygote; D006801:Humans; D009154:Mutation / Q000235:genetics; D010314:Partial Thromboplastin Time; D010949:Plasma / Q000737:chemistry; D011486:Protein C / Q000032:analysis; D012015:Reference Standards; D012680:Sensitivity and Specificity
chemical_list: D011486:Protein C; C095381:factor V Leiden; D005165:Factor V