Heparin Inhibition of Endotoxin-Dependent Limulus Amebocyte Lysate Coagulation^[*]

Summary

Addition of commercial heparin to preparations of the coagulation system obtained by hypotonic lysis of Limulus amebocytes, prior to the addition of endotoxin from gram-negative bacteria, inhibited gelation. Activation of the cell-lysate proclotting enzyme, utilizing a diluted lysate preparation and synthetic substrates, was inhibited to a comparable extent with either anticoagulantly active or inactive heparin. Other glycosaminoglycans, including heparan sulfate, dermatan sulfate, chondroitin 4-sulfate, and chondroitin 6-sulfate, did not inhibit the generation of clotting enzyme activity. Experiments conducted with preparations of proactivator(s) and proclotting enzyme, obtained by fractionation of lysate with heparin-Sepharose, revealed that inhibition of endotoxin-dependent activation of amebocyte lysate by heparin is mediated by precipitation of the proactivator(s) and can be prevented by increasing the salt concentration.

Keywords

Heparin - Coagulation - Amebocyte lysate - Limulus

Supported, in part, by a Summer Fellowship (Marine Biological Laboratory, Woods Hole, MA) awarded to J.A.M.; Research Grants HL34800 and HL31035 from the National Heart, Lung, and Blood Institute, N. I. H., Bethesda, MD; and the Veterans Administration.

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