ABSTRACT
Lipid-protein particles with platelet factor 3 measured by the Stypven clotting-time test [Hardisty & Hutton (1966) Br. J. Haematol. 12, 764-776] have been isolated from platelet-release supernatant. Starting material was washed platelets, which were released by treatment with collagen. Purification of the particles from other components in the release material was accomplished by gel filtration on Sepharose CL-4B followed by affinity chromatography on poly-L-lysine-Sepharose CL-4B gel. Chemical characterization showed that the particles were composed of 40% protein, 42% phospholipids, 13% cholesterol and 5% triacylglycerols. The phospholipid composition was 38% phosphatidylcholine, 25% phosphatidylethanolamine, 9% phosphatidylserine, 2% phosphatidic acid and 26% sphingomyelin. No carbohydrate was detected. Electron-microscopic studies revealed the presence of membranous particles with diameters between 70 and 170 nm.
Subject(s)
Blood Coagulation Factors/isolation & purification , Blood Platelets/analysis , Membrane Lipids/blood , Membrane Proteins/blood , Platelet Factor 3/isolation & purification , Blood Platelets/ultrastructure , Carbohydrates/analysis , Centrifugation , Chromatography, Affinity , Chromatography, Gel , Electrophoresis, Polyacrylamide Gel , Humans , Lipids/blood , Microscopy, ElectronSubject(s)
Blood Coagulation Factors/isolation & purification , Platelet Factor 3/isolation & purification , Animals , Antibodies , Blood Coagulation Tests , Chemical Phenomena , Chemistry , Chromatography, Gel , Cross Reactions , Electrophoresis, Polyacrylamide Gel , Female , Humans , Immunodiffusion , Lipids/analysis , Lipids/pharmacology , Molecular Weight , Neutralization Tests , Platelet Factor 3/immunology , RabbitsSubject(s)
Blood Coagulation Factors , Platelet Factor 3 , Animals , Blood Coagulation Factors/isolation & purification , Blood Coagulation Tests , Butanols/pharmacology , Cattle , Ethanol/pharmacology , Humans , Lipoproteins/isolation & purification , Phospholipases/pharmacology , Platelet Factor 3/analysis , Platelet Factor 3/isolation & purification , Platelet Factor 3/metabolism , Solvents/pharmacology , Trypsin/pharmacologyABSTRACT
The studies reviewed in the present manuscript outline the effects of bacterial endotoxins on human and animal platelets. In animals the endotoxin administration is followed by thrombocytopenia, presence of platelet aggregates in the blood vessels of several organs, appearance of appreciable quantities of serotonin in plasma and increased platelet factor 3 availability. These in vivo effects can readily be explained by the in vitro demonstration that endotoxin aggregates platelets, induces release of vasoactive amines and adenine nucleotides and activates platelet factor 3. There is substantial evidence suggesting that the mechanism of this animal platelet-endotoxin interaction is immunological and complement dependent. In humans thrombocytopenia is frequently observed in endotoxemia as encountered during Gram-negative sepsis indicating that platelets are involved in some of the biological effects endotoxin. In vitro experiments demonstrate that several endotoxin preparations significantly enhance a weak procoagulant activity of human platelets different from platelet factor 3.
