What is the Ideal Technique for Testing the Biocompatibility of Peritoneal Dialysis Solutions?

T he past few years have seen significant advances in our understanding of the inflammatory proc esses that occur in the peritoneal cavity of patients being treated for end-stage renal failure with peritoneal dialysis. These investigations have confirmed the importance of the peritoneal membrane and the mesothelium, in particular, as a site for the production of mediators important in the activation and control of inflammation (1-3). While it is apparent that peritonitis is still the major problem associated with continuous ambulatory peritoneal dialysis therapy, it is also clear that structural and functional changes in the peritoneal membrane occur in its absence (4,5). This has strengthened the belief that other factors, in addition to infection, are responsible for the long-term loss of peritoneal membrane function. Over the past 15 years, since the publication of the seminal paper by Duweet al. (6), extensive research effort has been focused on the question of peritoneal dialysis fluid (PDF) biocompatibility and the effects of components of commercial PDF on cell viability and function. These experiments have been performed on many different cell populations including peripheral and peritoneal leukocytes, as well as the cells of the peritoneal membrane, both in viva and in vitro [see Jörres et al. (7) for review]. The sum of these observations suggests that conventional PDF has significant modulatory and in some cases toxic effects on peripheral and peritoneal cell function. Little is known, however, about the impact of long-term exposure of the peritoneum to PDF and how its function as a dialyzing organ is altered. The current review will examine the field of PDF biocompatibility testing. It will seek to address the following questions: (1) What are the current test systems? (2) Are these test systems clinically relevant? (3) How can we improve biocompatibility testing? (4) What do the results ofbiocompatibility testing mean?