Protein S ELISA

Enzyme immunoassay for the quantitative determination of total and free Protein S in citrated human plasma.

INTENDED USE:Protein S is a solid phase enzyme immunoassay for the quantitative determination of Total and Free Protein S in citrated human plasma. The determination of Total and Free Protein S aids in the risk estimation of thrombosis.

GENERAL INFORMATION:Protein S is a vitamin K dependent glycoprotein of 70 kDa that is mainly synthesized by hepatocytes, but also by endothelial cells, Leydig cells in the testis, and megakaryocytes. In human plasma it is present at a concentration of 25 µg/ml and has a half-life of approximately two days. About 40 % of Protein S circulates in a functionally active free form, whereas 60 % is complexed with C4b-binding protein. Protein S plays an essential role in the Protein C anticoagulant system where the free Protein S functions as a cofactor of activated Protein C (aPC). Among the vitamin K dependent proteins Protein S has the highest affinity for negatively charged phospholipids and therefore increases the affinity of activated Protein C to membranes by forming a complex. This is of physiological importance since aPC inactivates preferentially the membrane-bound coagulation factors Va and VIIIa. Protein S deficiency may be inherited or acquired and increases the risk of thrombotic events such as deep vein thrombosis, pulmonary embolism, or thrombophlebitis. The prevalence of Protein S deficiency has been estimated to be up to one case per 300 in the general population. Nearly 50 % of individuals with inherited Protein S deficiency will experience a thrombotic event before the age of 45. Acquired Protein S deficiency occurs more frequently than the inherited form. Amongst others it can be found during oral anticoagulant therapy, oral contraceptive, pregnancy, liver disease, diabetes mellitus, chemotherapy and various inflammatory syndromes. Protein S deficiency is classified in three states. Type I deficiency is a reduction in the level of both Free and Total Protein S. Type II deficiency is characterized by a reduced Protein S activity, with normal antigen level. Type III deficiency corresponds to reducedA antigen level and activity of Free Protein S only. To determine the type of defect, the laboratory diagnosis of Protein S may require antigen levels of both Free and Total Protein S and functional determination.

KIT CHARACTERISTICS:
- Method: ELISA
- Tests: 96
- Incubation Time / Conditions: 30 min, 30 min (RT); 30 min (RT/dark)
- Standard Range: 12.5 - 150 %
- Sensitivity analytical: 1 %
- Final Sample Volume: 100 µl
- Sample Type: plasma
- Isotope / Substrate: TMB 450 nm
- Internal Controls: 2
- Regulatory Status: CE