A new assay based on thrombin generation inhibition to detect both protein C and protein S deficiencies in plasma.
Activated protein C reduces thrombin generation by inactivating factors V and VIII in the presence of protein S. This prompted us to develop an assay which would allow specific exploration of this reaction. The total amount of thrombin formed in plasma after activation by tissue factor and phospholipids was reduced by adding thrombomodulin. This addition allowed protein C to be activated by endogenous thrombin. The inhibition of thrombin generation (ITG) due to protein C activation could be measured by comparing thrombin formation in the presence and in the absence of thrombomodulin. ITG increased with both protein C and protein S concentrations. Normal values of ITG expressed as a percentage were between 40 and 65% and were not influenced by age or sex. ITG increased in patients under heparin therapy, decreased in patients under oral anticoagulant therapy and was decreased in women using oral contraceptives. This method could be used for screening patients for protein C and protein S deficiencies.
INSERM CJF 91-01, UFR des Sciences Pharmaceutiques et Biologiques, Université Paris V, France.
J
J
Duchemin
J L
JL
Pittet
M
M
Tartary
S
S
Béguin
P
P
Gaussem
M
M
Alhenc-Gelas
M
M
Aiach
D000595:Amino Acid Sequence; D000818:Animals; D001780:Blood Coagulation Tests / Q000379:methods*; D001793:Blood Preservation; D002863:Chromogenic Compounds; D005165:Factor V / Q000037:antagonists & inhibitors; D005169:Factor VIII / Q000037:antagonists & inhibitors; D005260:Female; D014644:Genetic Variation; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000494:pharmacology; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism; D011486:Protein C / Q000032:analysis; D020151:Protein C Deficiency; D017293:Protein S / Q000032:analysis; D018455:Protein S Deficiency; D011817:Rabbits; D012016:Reference Values; D015203:Reproducibility of Results; D013917:Thrombin / Q000096:biosynthesis*; D018180:Thrombomodulin / Q000378:metabolism; D013925:Thromboplastin / Q000378:metabolism
D002863:Chromogenic Compounds; D016682:Lupus Coagulation Inhibitor; D010743:Phospholipids; D011486:Protein C; D017293:Protein S; D018180:Thrombomodulin; D005165:Factor V; D005169:Factor VIII; D013925:Thromboplastin; D013917:Thrombin