Immuno Aktiengesellschaft

Berta Moritz

Hartmut Lang

Hans Peter Schwarz

Katalin Varadi

Olga Lukas

Manfred Oberreither

An improved assay for determining sensitivity to activated protein C in test samples has been developed to ensure rapid and accurate evaluations. This assay is based on measuring the conversion, by activated factor VIII within a test sample, of added factor X to an activated form. The activated protein C sensitivity of the test sample is determined by the relative inhibition of factor X conversion as compared to a control. A test sample that has decreased sensitivity to activated protein C will show relatively low inhibition, and vice versa.

Assay for determining sensitivity to activated protein C

There is disclosed the use of prothrombin fragments, preferably of human prothrombin fragments, having a thrombin-like activity, in particular of meizothrombin, meizo thrombin (desF1), or mixtures thereof, for diagnostic purposes for assaying thrombin substrates as well as a reagent containing these prothrombin fragments.

Method of assaying plasma proteins with prothrombin fragments

To determine the factor VIII activity of a sample, the latter is reacted with a reagent containing thrombin, factor IXa.beta., phospholipids and calcium ions so as to form a factor VIIIa-factor IXa-phospholipid-calicum ion-containing complex. This complex is reacted with factor X so as to obtain activated factor X. The obtained factor Xa is reacted with chromogenic substrate so as to form a substance to be determined spectrophotometrically. Complex formation and activation of factor X are effected in one stage: The sample is mixed with a mixture of human thrombin, phospholipids, calcium ions, human factor IXa.beta., human factor X and, if desired, human factor XIa and human factor XIIa, as a complex-forming reagent.

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Vienna, Austria

Berta Moritz