Instrumentation Laboratory

Instrumentation Laboratory S.r.l.

Luigi Preda

Antonio Lombardi

The present invention provides a method for determining thrombotic risk in an individual. The method involves determining the activity of Protein C and Protein S in the plasma of the individual thought to be at thrombotic risk by adding to a plasma sample obtained from the individual (i) a first reagent in an amount sufficient to induce or activate coagulation in the plasma, (ii) a second reagent which activates endogenous protein C in the plasma, and (iii) a third reagent comprising calcium salts, phospholipids or tissue thromboplastin, or a combination thereof. To a second plasma sample from the same subject is added a reagent which induces or activates coagulation, and a buffer or other material which does not activate protein C, and a third reagent as described above. The time, rate or both, necessary for the conversion of endogenous fibrinogen to fibrin in both the first and second samples is measured. The same steps are performed on normal control plasma, and the difference or ratio in the times, rates, or both, obtained above are determined. The difference or ratio is indicative of the thrombotic risk in the subject. A kit adapted to carry out the method also is the subject of the present invention. The methods and kits of the invention in other embodiments may comprise a first reagent comprising a synthetic substrate, a second reagent which in the first sample from the subject activates protein C, and in the second sample, a second reagent which does not activate protein C. In these embodiments, the rates of hydrolysis of the synthetic substrates are measured and compared.

Protein C pathway screening test

To determine the biological activity of protein S in a sample of human plasma, the suitably diluted sample is added to a substrate formed from plasma deficient in protein S, in which protein C is activated. The functionality of protein is evaluated by a coagulometric test using bovine thromboplastin with added calcium as the phospholipid source. Also disclosed is a kit for determining the activity of Protein S in a human plasma sample. The kit includes a first reagent which is human plasma deficient in protein S, a second reagent which contains an activator for protein C, and a third reagent which contains bovine thromboplastin.

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Verano Brianza, Italy

Luigi Preda