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Expression and localization of tissue factor-based procoagulant activity (PCA) in pigeon monocyte-derived macrophages
M Gupta1, G J Doellgast, T Cheng
1Department of Pathology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157-1092.
Abstract:
Monocyte-derived macrophages, focal to initiation and progression of atherosclerosis, have been implicated in thrombotic complication of this disease. In the present study we demonstrated tissue factor based procoagulant activity in cultured macrophages from the White Carneau pigeon following endotoxin (1-2 micrograms/ml) stimulation. This macrophage procoagulant activity paralleled activity obtained with pigeon brain homogenate. We used Enzyme-Linked Coagulation Assay (ELCA), an ultrasensitive microtiter plate assay, to measure procoagulant activity in these cells. Through the use of clotting factors purified from pigeon plasma, procoagulant activity could be detected with as few as 1-3 cells. Tissue factor antigen, detected through the use of immunogold labelling in conjunction with a polyclonal antibody which was highly specific to human tissue factor, was distributed uniformly over the plasma membrane of the endotoxin-stimulated cells. These studies suggest that this procoagulant activity might play an important role in the pathobiology of atherosclerosis in White Carneau pigeons by initiating fibrin polymerization and thus leading to thrombotic complications of the disease.
Insights
Macrophages in White Carneau pigeons exhibit tissue factor-based procoagulant activity after endotoxin stimulation. This finding suggests a role for these cells in initiating fibrin polymerization and thrombotic complications of atherosclerosis.
Area of Science:
- Cardiovascular Biology
- Immunology
- Hematology
Background:
- Monocyte-derived macrophages are central to atherosclerosis initiation and progression.
- These cells have been linked to thrombotic complications in cardiovascular disease.
Purpose of the Study:
- To investigate tissue factor-based procoagulant activity in cultured macrophages from White Carneau pigeons.
- To explore the role of this activity in the pathobiology of atherosclerosis and its thrombotic complications.
Main Methods:
- Cultured macrophages from White Carneau pigeons were stimulated with endotoxin.
- Enzyme-Linked Coagulation Assay (ELCA) was used to measure procoagulant activity.
- Immunogold labeling with a polyclonal antibody specific to human tissue factor detected tissue factor antigen.
Main Results:
- Endotoxin stimulation induced significant tissue factor-based procoagulant activity in pigeon macrophages.
- This activity was comparable to that observed in pigeon brain homogenate.
- Tissue factor antigen was uniformly distributed on the plasma membrane of stimulated macrophages.
- Procoagulant activity was detectable with as few as 1-3 cells.
Conclusions:
- Cultured pigeon macrophages possess potent procoagulant activity mediated by tissue factor.
- This macrophage-derived procoagulant activity may contribute to fibrin polymerization and thrombotic events in atherosclerosis.
- These findings highlight a potential mechanism in the pathobiology of atherosclerosis in this avian model.