IN-VITRO EFFECTS OF AMINO-ACID-BASED VERSUS GLUCOSE-BASED CONTINUOUS AMBULATORY PERITONEAL-DIALYSIS FLUIDS ON PERITONEAL MACROPHAGE FUNCTION

We studied the in vitro effects of peritoneal dialysis fluids (PDF) co ntaining 1 and 1.5% amino acids (AA) as compared to approximately equi osmolar glucose (GLU)-based PDF (1.5 and 4.25%) and control buffer, re spectively, on peritoneal macrophage (PMO) function. The media were te sted at original pH (5.3-5.5) and after pH adjustment to 7.4. PMO were isolated from the effluents of 10 on continuous ambulatory peritoneal dialysis (CAPD) patients and tested for luminol- and lucigenin-enhanc ed chemiluminescence (CL), superoxide generation measured by cytochrom e c reduction, killing capacity and phagocytosis after incubation (30 min, 37 degrees C) in the PDF used. All AA-based PDF exhibited a stati stically significant depressive effect on integral CL response, O-2(-) production and bacterial killing of PMO at pH 7.4 in comparison with pH-adjusted GLU-based PDF of similar osmolality and buffer. Exposure o f PMO to acidic AA-based media did not result in a significantly diffe rent suppression of the oxidative metabolism and the killing capacity as compared to fresh GLU-based fluids. Phagocytosis of PMO did not sho w significant differences after incubation in the solutions studied. T hus, the AA-based PDF employed compromise the oxidative metabolism and the killing capacity of PMO at pH 7.4 in vitro significantly more tha n GLU-based fluids. Since pH-identical and almost equiosmolar PDF were compared, the specific composition of the AA-based fluids, especially the high content of lactate and several essential AA, could be respon sible for this detrimental impact.