Increased levels of platelet-activating factor in blood from patients with cirrhosis of the liver.

The levels of platelet-activating factor (paf-acether) were measured in blood and ascitic fluid from cirrhotic patients and in blood from a group of controls, using a recently described technique for extraction and measurement. In addition, activity of acetylhydrolase, the main catabolic enzyme for paf-acether, was also measured. The highest levels of paf-acether in blood were found in decompensated cirrhotics (1.78 +/- 0.62 ng ml-1; mean +/- SD, n = 8). Compensated cirrhotics showed lower blood values (0.79 +/- 0.21, n = 4), but higher than controls (0.20 +/- 0.04, n = 12). Paf-acether levels in ascitic fluid were similar to those of blood. Values of acetylhydrolase in serum were similar in all the groups studied (3.0 +/- 0.4 in cirrhotics vs. 2.3 +/- 0.4 nmol min-1 mg-1 of protein in controls). These data suggest an enhanced production of paf-acether in cirrhotic patients rather than a decreased catabolism. High levels of paf-acether in blood could be involved in the impaired haemodynamics of cirrhotic patients and in their renal function alterations.