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Published on: September 9, 2012
Coagulant activity of leukocytes. Tissue factor activity
The Journal of Clinical Investigation
|February 1, 1972
Summary
Endotoxin administration significantly increases the coagulant activity of rabbit peritoneal leukocytes, identified as tissue factor. Polymyxin B reduces this activity when given with the initial endotoxin dose.
Area of Science:
- Immunology
- Hematology
- Biochemistry
Background:
- Endotoxin exposure can modulate immune cell functions.
- Leukocytes possess procoagulant properties, particularly tissue factor.
- Understanding tissue factor induction is crucial for inflammatory and coagulation research.
Purpose of the Study:
- To quantify the coagulant activity of peritoneal leukocytes following endotoxin administration.
- To characterize the nature and localization of this procoagulant activity.
- To investigate the effect of Polymyxin B on endotoxin-induced leukocyte procoagulant activity.
Main Methods:
- Rabbits received spaced doses of endotoxin.
- Peritoneal leukocytes were harvested and their coagulant activity measured.
- Subcellular fractionation and heat stability assays were performed.
- The impact of Polymyxin B administration timing was assessed.
Main Results:
- Endotoxin-treated rabbits showed a 10-fold increase in leukocyte coagulant activity (tissue factor).
- Tissue factor activity was localized in fractions sedimenting at 14,500 g and above.
- Procoagulant activity was heat-labile above 65°C but stable at lower temperatures.
- Polymyxin B reduced leukocyte numbers and tissue factor activity by two-thirds when given with the first endotoxin dose.
Conclusions:
- Peritoneal leukocytes are a significant source of tissue factor following endotoxin challenge.
- The timing of Polymyxin B administration is critical for its inhibitory effect on endotoxin-induced tissue factor.
- These findings provide insights into the interplay between endotoxin, leukocytes, and the coagulation system.
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