HIGHLY SENSITIVE ASSAY OF PLATELET FACTOR-3 USING A CHROMOGENIC SUBSTRATE

A sensitive method for the determination of platelet factor 3 (PF 3) is described. The principle of the method is to measure thrombin generation in a mixture of prothrombin complex concentrate, Russell's viper venom, Ca2+ and the sample containing PF 3 activity. Thrombin generation is determined by spectrophotometric measurements using a chromogenic synthetic peptide HDPhePipArgp-nitroanilide (S-2238), as a substrate for thrombin. The assay is about ten times as sensitive as the Stypven clotting time, commonly used to determine PF 3. Determinations in eighteen normal blood donors showed varying levels of PF 3 activity that seemed to be individually related. For most individuals the values obtained were essentially the same from one occasion to another. © 1979.