Genesis of fibronectin in ascites--detection of cellular and plasma fibronectin in portal and malignant ascites

Measurement of fibronectin in ascites has been proposed for the differentiation of ascites either due to malignant growth in the peritoneal cavity or liver cirrhosis with portal hypertension. The high ascitic fibronectin concentration in patients with peritoneal carcinomatosis was thought to be due to the synthesis of this protein by neoplastic cells. Therefore in ascites of malignant origin cellular fibronectin should be present as it is synthesized by neoplastic cells. On the other side the transsudative ascites due to liver cirrhosis with portal hypertension should mainly contain plasma-fibronectin, which is secreted by hepatocytes into the bloodstream. With the aid of two different monoclonal antibodies and immunoblotting of partially digested or intact ascitic fibronectin, cellular fibronectin could be demonstrated in ascitic fluid of 10 patients with peritoneal carcinomatosis, 13 patients with liver cirrhosis, one patient with right-sided heart failure and one patient with Budd-Chiari-Syndrome. As determined by a specific ELISA 8 out of 10 samples of malignant ascites contained more than 30 mg/l of cellular fibronectin, whereas 10 out of 13 samples of ascites due to liver cirrhosis contained less than 10 mg/l. Whereas in ascites of malignant origin cellular fibronectin represented about 20% of total fibronectin, in portal ascites fibronectin represented sometimes more than 50% of total fibronectin. Cellular fibronectin of non-malignant origin is probably produced by mesothelial cells or peritoneal macrophages. Therefore, fibronectin accumulating in peritoneal carcinomatosis is only to some extent locally produced, but mainly caused by an unhindered exsudation of plasma-fibronectin.