Quantitative Determination of Platelet Factor 3 Activity

Abstract

SummaryA method for the quantitative determination of platelet factor 3 (PF 3) is described. It is based on the prothrombin consumption and allows the determination of the total PF 3, of the PF 3 made available under various conditions and of PF 3 like activity.The material to be tested is recalcified in the presence of a normal PPP pool to maintain the intrinsic clotting factors in the optimal concentration range. After an appropriate incubation the coagulation is stopped by a citrate solution and the clot removed. The residual prothrombin activity in citrated serum is indirectly proportional to the PF 3 activity. This activity can be expressed in per cents by means of a reference curve which can be established with Cephaloplastin (Dade) dilutions. The 100% value is given by the total average PF 3 activity when the platelet count in PRP is adjusted to 100,000 platelets/mm3. An appropriate correction is needed when the prothrombin concentration is too low in the tested PRP.In 50 healthy blood donors the PF 3 activity ranged between 70-130% with quite small day to day variations.

Thrombocytopathia with Abnormalities in Platelet Release Reaction

“…The latter was defined as 100°/o at same volunteer, a dilution curve was obtained for each individual. Quan titative determination of PF 3 activity was also tested according to Poi.aSek and Duckert [25].…”

Diagnosis of Quinine Hypersensitivity, Use of Platelet Factor 3 and Acid Phosphatase Availability Tests

“…(b) Quantitative assay based on the prothrombin consumption [15]. The test system has been slightly modified.…”

“…At various time in tervals 0.2 ml PPP-pool and 0.1 ml kaolin suspension are added to the incubated plasma and the mixture recalcified. The restprothrombin is then determined aftei stopping the reaction with citrate and removal of the clot according to the original method [15].…”

“…In some experiments the assay was made in presence of CaCl2 to study the effect of Ca ions on the demasking of the acid phosphatase. The assays were performed as follows: 0.15 ml 0.1 m CaCI2 containing 15 units heparin were added to 1 ml citrated normal or patient's PRP followed by 0.1 ml of the tested drug or Tris sa line. In control experiments the calcium chloride solution was replaced by 0.15 ml Tris saline containing 15 units heparin.…”

“…lb). Using the quantitative assay for PF 3 [15] it can be demonstrated that 3-5 times more PF 3 activity is de-masked under the influence of 2.5 X 10~3 M quinine as compared with Tris saline alone which does not liberate appreciable amount of PF 3. In case 2 again the other drugs are without effect ( fig.…”