title: A platelet derived inhibitor of plasma prekallikrein activation.
abstract: Platelet products released by ADP mediated platelet aggregation or by repeated freeze-thawing of platelet-rich-plasma caused inhibition of the dextran sulphate induced activation of prekallikrein, measured amidolytically, in subsequently prepared platelet-poor-plasma. Platelet products did not inhibit the amidolytic activity of contact activated-plasma. Addition of antiserum to platelet factor-4 (PF4) neutralized the inhibitory effect of platelet products towards prekallikrein activation. When platelet released products were fractionated by heparin affinity chromatography, 93% of the PF4 applied and 86% of the inhibitory activity of the starting material was recovered in the high-affinity fraction.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000328:Adult; D000918:Antibody Specificity; D002846:Chromatography, Affinity; D003911:Dextrans / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007610:Kallikreins / Q000096:biosynthesis*; D010949:Plasma / Q000032:analysis; D010974:Platelet Aggregation / Q000187:drug effects; D010978:Platelet Factor 4 / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*; D011288:Prekallikrein / Q000096:biosynthesis*
chemical_list: D003911:Dextrans; D007106:Immune Sera; D010978:Platelet Factor 4; D000244:Adenosine Diphosphate; D011288:Prekallikrein; D007610:Kallikreins