title: Coagulant activity of leukocytes. Tissue factor activity.
abstract: Peritoneal leukocytes harvested from rabbits which have received two spaced doses of endotoxin have significantly greater (10-fold) coagulant activity than leukocytes from control rabbits. The coagulant activity accelerates the clotting of normal plasma and activates factor X in the presence of factor VII and calcium and is therefore regarded as tissue factor. A total of 40-80 mg tissue factor activity was obtained from the peritoneal cavity of single endotoxin-treated rabbits. In leukocyte subcellular fractions, separated by centrifugation, the specific tissue factor activity sedimented mainly at 14,500 g and above. The procoagulant activity was destroyed after heating for 10 min at 65 degrees C but was preserved at lower temperatures. Polymyxin B, when given with the first dose of endotoxin, reduced both the number of peritoneal leukocytes and their tissue factor activity by two-thirds. When given immediately before the second dose of endotoxin, polymyxin B had no inhibitory effect.
mesh_terms: D000818:Animals; D001777:Blood Coagulation; D002403:Cathepsins / Q000097:blood; D004211:Disseminated Intravascular Coagulation / Q000097:blood; D004731:Endotoxins / Q000494:pharmacology; D005167:Factor VII; D005170:Factor X; D006801:Humans; D007962:Leukocytes / Q000187:drug effects / Q000201:enzymology; D008297:Male; D011113:Polymyxins / Q000494:pharmacology; D011817:Rabbits; D012790:Shwartzman Phenomenon / Q000097:blood; D014020:Tissue Extracts
chemical_list: D004731:Endotoxins; D011113:Polymyxins; D014020:Tissue Extracts; D005167:Factor VII; D005170:Factor X; D002403:Cathepsins