SERUM PAF-ACETYLHYDROLASE IN SEVERE RENAL OR HEPATIC-DISEASE IN MAN -RELATIONSHIP TO CIRCULATING LEVELS OF PAF AND EFFECTS OF NEPHRECTOMY OR TRANSPLANTATION

(1) PAF-acetylhydrolases form a major pathway for the degradation of p latelet-activating factor (PAF). Here we investigate the role of the k idney and the liver in the control of PAF-acetylhydrolase levels by co mparing normal subjects to patients with abnormal liver or kidney func tion. These patients had either severe chronic liver disease, chronic renal failure or were anephric. In a few cases PAF was also measured. (2) In those patients where PAF was measured there was no evidence tha t circulating PAF levels determined PAF-acetylhydrolase release. (3) I n anephric patients serum PAF-acetylhydrolase levels were normal or ev en raised. Therefore the kidney is unlikely to be the usual major sour ce of serum PAF-acetylhydrolase in man. (4) Liver patients with chroni c cholestasis had elevated serum PAF-acetylhydrolase especially in sta ge III or IV primary biliary cirrhosis, as well as in a patient with s econdary biliary cirrhosis and one with cholangiocarcinoma. Since norm alisation of liver function following liver transplantation was accomp anied by a reduction to normal or near normal PAF-acetylhydrolase leve ls, it is likely that the liver can play an important role in regulati ng levels of this enzyme in serum.