A single administration of peritoneal dialysis fluid in the rat induces an acute inflammatory exudate.

Peritoneal macrophages from uninfected continuous ambulatory peritoneal dialysis (CAPD) patients in general show two different, endogenous peroxidatic activity (PA) patterns: exudate and negative. This suggests, in accordance with the animal model, that a chronic inflammatory state is present in CAPD patients, which may be caused by mechanical stimulation or the dialysis fluid. Therefore we studied in the rat model the intraperitoneal (i.p.) administration of peritoneal dialysis fluid and physiological saline. Our results on the number of neutrophilic granulocytes, the number of macrophages and the PA pattern indicate that a single i.p. administration of commercial dialysis fluid induced an acute exudate, especially when compared with the minor saline effect. These results are confirmed by the lower percentage of macrophages positive for the differentiation antigen ED2 and in addition the higher number of Fc-receptor positive peritoneal cells, when compared with the saline effect. These findings strongly suggest that the continuous administration of the dialysis fluid, as used in CAPD patients, is the inducer of the chronic inflammatory exudate in these patients.