Thromb Haemost 1983; 49(02): 069-072
DOI: 10.1055/s-0038-1657323
Original Article
Schattauer GmbH Stuttgart

Platelets Stimulate Thromboplastin Synthesis in Human Endothelial Cells

U L H Johnsen
The Research Institute for Internal Medicine, University of Oslo, Rikshospitalet, Oslo, Norway
,
T Lyberg
The Research Institute for Internal Medicine, University of Oslo, Rikshospitalet, Oslo, Norway
,
K S Galdal
The Research Institute for Internal Medicine, University of Oslo, Rikshospitalet, Oslo, Norway
,
H Prydz
The Research Institute for Internal Medicine, University of Oslo, Rikshospitalet, Oslo, Norway
› Author Affiliations
Further Information

Publication History

Received 28 July 1982

Accepted 09 December 1982

Publication Date:
18 July 2018 (online)

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Summary

Human umbilical vein endothelial cells in culture synthesize thromboplastin upon stimulation with phytohaemagglutinin (PHA) or the tumor promotor 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The thromboplastin activity is further strongly enhanced in a time dependent reaction by the presence of gel-filtered platelets or platelet aggregates. This effect was demonstrable at platelet concentrations lower than those normally found in plasma, it may thus be of pathophysiological relevance. The thromboplastin activity increased with increasing number of platelets added. Cycloheximide inhibited the increase, suggesting that de novo synthesis of the protein component of thromboplastin, apoprotein III, is necessary.

When care was taken to remove monocytes no thromboplastin activity and no apoprotein HI antigen could be demonstrated in suspensions of gel-filtered platelets, platelets aggregated with thrombin or homogenized platelets when studied with a coagulation assay and an antibody neutralization technique.