title: Assay of prekallikrein as plasminogen proactivator in plasma specimens from reactors to dextran or to contrast media.
abstract: In a previous study of plasma specimens from reactors to clinical dextran, it was concluded that a factor activated by acetone converted the high-molecular-weight kininogen (HMrK) into a non-functional state. We recently identified the HMrK-destroying factor as a plasma kallikrein modification with high plasminogen activator (PGA) activity. The aim of the present work was to investigate whether the level of plasma kallikrein, assayed as PGA on fibrin plates, was higher than normal in plasma from patients reacting to dextran or radiographic contrast media. Plasma specimens from 10 reactors and 16 controls were examined. No difference in PGA level could be detected between reactors and controls in citrated plasma stabilized with benzamidine 9 mM, whereas a significant loss of PGA activity took place in citrated reactor plasma during the acetone activation procedure. The loss of PGA activity could not be due to known inhibitors of plasma kallikrein. It was only partial, and did not influence the amidase effect against the tripeptide substrate H-D-Pro-Phe-Arg-pNA. The results might indicate the presence in plasma of different amounts of an unknown constituent important for the obtainable level of plasma kallikrein with high PGA activity. The significant loss of PGA activity in reactor plasma might indicate an abnormally high level of the unknown plasma factor.
mesh_terms: D000096:Acetone; D000328:Adult; D000581:Amidohydrolases / Q000097:blood; D003287:Contrast Media / Q000276:immunology*; D003911:Dextrans / Q000276:immunology*; D004342:Drug Hypersensitivity; D004950:Esterases / Q000097:blood; D005260:Female; D006801:Humans; D007610:Kallikreins / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010960:Plasminogen Activators / Q000097:blood*; D011288:Prekallikrein / Q000276:immunology*
chemical_list: D003287:Contrast Media; D003911:Dextrans; D000096:Acetone; D011288:Prekallikrein; D004950:Esterases; D007610:Kallikreins; D010960:Plasminogen Activators; D000581:Amidohydrolases