Thrombin inhibition by malignant and normal cells: a cell-bound antithrombin effect

Analysis of fresh surgical specimens of normal tissue and tumor tissue show a cellular antithrombin activity to be present in certain organs. In normal tissues it was noted chiefly in normal colon, testes, breast, and uterus. In malignant tissues it was prominent in adenocarcinomas of the colon, breast, and lung. No epidermoid tumors showed evidence of thrombin binding. The thrombin- binding activity required the presence of intact cells and was distinct from the soluble antithrombins normally present in plasma and serum. There is growing evidence to suggest an interrelationship between clotting and the growth and dissemination of cancer. The implications of cellular antithrombins are reviewed in this context.