Protein C 

Activity and Antigen assays

Introduction

Protein C (PC) is a vitamin K dependent human protein of the coagulation system, synthesized in the liver, of about 62 KDa. PC is usually present in plasma as a proenzyme, at a concentration of about 4-5 µg/ml. When activated by thrombin (and thrombomodulin), in presence of calcium and phospholipids, activated Protein C, in presence of Protein S, inhibits and regulates coagulation through specific cleavages of Factors Va and VIIIa, suppressing their procoagulant cofactor activity. Protein C action is very efficient in micro blood circulation, where the thrombomodulin density is dramatically increased respectively to blood volume.

By definition, the 100 % Protein C concentration corresponds to the concentration in a normal human citrated plasma pool, obtained by pooling plasmas from healthy males or females aged from 18 to 55 years, and out of any medication. The Protein C concentration in adults is usually between 70 and 140%1. The Protein C concentration is decreased in neonates.  It is then independent from age or gender.

A Protein C concentration ≤60 % indicates the presence of a deficiency, which must be confirmed by another measurement, or another sample collected from the patient1. Protein C activity is reduced during dicoumarol therapy, in hepatic diseases, in disseminated intravascular coagulation (DIC), or in presence of a congenital deficiency. The latest is most of the time associated with recurrent venous thrombosis. Both quantitative and qualitative decreases in PC exist, the former being type I deficiency and the latter, type II.

Overview Assays

Product Name Assay principle Refrence Package
BIOPHENTM Protein C (LRT) (CE-IVD)  Chromogenic method for in vitro quantitative determination of Protein C activity on human citrated plasma3,4. Reagents are in the liquid presentation, ready to use (LRT, Liquid Reagent Technology). 221211  R1: 3 x 3 ml

R2: 3 x 3 ml

More info
HEMOCLOT Protein C    (CE-IVD)  Clotting based Protein C activity test for the quantitative determination of Protein C in human citrated plasma. CK031K   3 x 1ml  More info
 ZYMUTESTTM Protein C  (CE-IVD)  A highly sensitive two-site immuno-assay for measuring human Protein C in citrated plasma, or in any biological fluid where Protein C can be present. RK027A  96 tests

 

References

  1. Mannucci P.M., Vigano S. : Deficiencies of Protein C, an inhibitor of blood coagulation. Lancet, 2, 463-467, (1982).
  2. Pabinger I. : Clinical relevance of Protein C. Blut 53, 63-75 (1986).
  3. Horellou M.H. : Intérêt du dosage de la Protéine C dans les accidents thromboemboliques veineux. Feuil. Biol., 26,27-31, (1985).
  4. Stenflo J. : Structure and Function of Protein C. Semin. Thromb. Haemostasis, 10,2, 109-121, (1984).
  5. Esmon C.T.: Protein C activation. Semin. Thromb. Haemostasis, 10,2, 122-133, (1984).
  6. Dahlbäck B., Villoutreix B.O., Molecular recognition in the protein C anticoagulant pathway. J. Thromb. Haemost., 1, 1525-34, (2003).