A functional assay for protein C in human plasma.
We describe a functional assay for protein C in human plasma samples based on the ability of activated protein C to prolong the kaolin-cephalin activated partial thromboplastin time of normal plasma. Protein C is separated from its inhibitor by elution of a barium citrate precipitate, and activated by incubation with human alpha-thrombin for one hour. Thrombin is then inhibited by antithrombin III and heparin, heparin neutralized by protamine sulfate, and protein C activity measured in the partial thromboplastin time. 24 normal subjects had a mean protein C level of 94 +/- 12% (SD) of the activity in pooled normal plasma. Seven patients with severe liver disease had a mean protein C of 28%. Eleven patients with disseminated intravascular coagulation had a mean protein C of 29%. Eight patients receiving warfarin therapy had a mean protein C of 17%. The assay is relatively simple and should be suitable for general laboratory use.
D004211:Disseminated Intravascular Coagulation / Q000097:blood; D006023:Glycoproteins / Q000097:blood* / Q000502:physiology; D006801:Humans; D008107:Liver Diseases / Q000097:blood; D010314:Partial Thromboplastin Time; D010949:Plasma / Q000032:analysis; D011486:Protein C
D006023:Glycoproteins; D011486:Protein C