Occlusion of pulmonary vessels by megakaryocytes after treatment with tumour necrosis factor-alpha (TNF-alpha)

Pulmonary thrombosis in the course of shock remains life-threatening, despi te advances in diagnosis, prophylaxis and therapy of the disease. Tumour ne crosis factor-alpha (TNF-alpha) is an important mediator of shock. The aim of this study was to analyze the morphological changes in the pulmonary cap illary bed in rats after intraperitoneal administration of multiple doses o f TNF-alpha (10 mu g TNF-alpha/24 h for 5 days; biological activity of 2-4 x 10(7) U/mg of protein), Morphological investigations were undertaken by l ight and transmission electron microscopy with emphasis on pulmonary thromb opoiesis. The study confirmed that the lungs may be an important site of ex tramedullary thrombopoiesis in the course of shock. The observations also s uggested that megakaryocytes shed large fragments of cytoplasm within the p ulmonary capillary bed and that megakaryocytes with copious cytoplasm occlu de pulmonary vessels. (C) 1999 W.B. Saunders Company Limited.