Purification of human complement factor D from the peritoneal fluid of patients on chronic ambulatory peritoneal dialysis.

We describe a simple procedure for the purification of human factor D from the peritoneal fluid (PF) of patients with end stage renal failure (ESRF) on chronic ambulatory peritoneal dialysis (CAPD). The main advantages of this method are: (1) a relative enrichment of factor D in PF versus plasma (factor D/total protein enriched 3.8-fold); thus, added to the elevated concentration of factor D in ESRF, the enrichment compared to normal human serum is approximately 50 fold. (2) This biological source of factor D is almost unlimited, since around 10 liters of PF are removed per day from each patient. The purification is performed in three simple steps-Bio Rex 70, Heparin Sepharose CL 6B and Mono S FPLC- and milligrams of highly purified factor D are obtained. Peritoneal fluid might be a valuable source for the purification of other low MW proteins which accumulate in renal failure.