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The endotoxin-induced coagulant activity of human monocytes
Abstract:
Leucocyte suspensions, exposed to endotoxin in vitro, develop coagulant activity which has been identified as tissue factor. Pure suspensions of polymorphonuclear (PMN) neutrophils, lymphocytes and monocytes were exposed to endotoxin and tested for tissue factor activity after 4 h incubation at 37 degrees C. The results indicate that the monocyte is the cell primarily responsible for the endotoxin-induced coagulant activity of mixed leucocyte suspensions, the small amount of activity demonstrated in PMN neutrophil and in lymphocyte suspensions at high cell concentrations being accounted for by monocyte contamination of less than 1%.
Insights
Endotoxin exposure in vitro induces coagulant activity in white blood cells (leukocytes). Monocytes are the primary cells responsible for this endotoxin-induced tissue factor activity in mixed leukocyte suspensions.
Area of Science:
- Immunology
- Hematology
- Cell Biology
Background:
- Leukocytes, upon in vitro exposure to endotoxin, exhibit coagulant activity.
- This coagulant activity has been identified as tissue factor (TF).
Purpose of the Study:
- To determine which specific leukocyte subset is primarily responsible for endotoxin-induced TF activity.
- To investigate the role of polymorphonuclear (PMN) neutrophils, lymphocytes, and monocytes in this response.
Main Methods:
- Preparation of pure suspensions of PMN neutrophils, lymphocytes, and monocytes.
- Incubation of these cell suspensions with endotoxin for 4 hours at 37°C.
- Assay of tissue factor activity in the incubated cell suspensions.
Main Results:
- Monocytes were identified as the principal cell type mediating endotoxin-induced coagulant activity.
- Minimal TF activity observed in PMN neutrophil and lymphocyte suspensions was attributed to less than 1% monocyte contamination.
Conclusions:
- Monocytes are the primary effector cells responsible for endotoxin-induced tissue factor generation in leukocyte populations.
- The contribution of PMN neutrophils and lymphocytes to endotoxin-induced coagulant activity is negligible, likely due to minor monocyte contamination.
