Protection by glutathione of neutrophils against the toxic effects of peritoneal dialysis fluid.

The possibility of reducing the cytotoxic effect of heat-sterilized peritoneal dialysis (PD) fluid by addition of antioxidants/scavengers during incubation of titanium-adhering cells was investigated. Capillary blood from healthy donors was placed in drops on commercially available titanium pieces and incubated in a humidified chamber at 37 degrees C for 60min. After incubation the adherent polymorphonuclear leukocytes were immersed for 1-4h in PD-fluid, pH 7.4, containing 2.5% glucose with glutathione (GSH), superoxide dismutase, catalase or dithiothreitol (DTT). Luminol- or isoluminol-amplified chemiluminescence was used to measure the zymosan- and phorbol myristate acetate (PMA)-stimulated respiratory burst activity, as an indicator of the cytotoxicity of the PD-fluids. Heat sterilized PD-fluid had inhibitory effect on zymosan-induced respiratory burst and impaired both the extracellular and intracellular PMA-induced respiratory burst. Addition of GSH to the PD-fluid resulted in reduction of cytotoxical effects on the zymosan-induced and extracellular PMA-induced respiratory burst. The intracellular respiratory burst was not affected. The present results show that GSH and DTT have the ability to protect polymorphonuclear leukocytes against the cytotoxic effects of the PD-fluid by keeping the cell membrane in a reduced state.

The respiratory burst response of surface-adhering leukocytes. A key to tissue engineering.

Biomaterials implanted into tissue will participate in the complex signalling between cells during wound healing. Recent studies have revealed that crucial cellular signalling pathways are regulated by the extra- and intracellular redox states and that reactive oxygen species function as intercellular signal molecules. Biomaterials have been shown to affect the respiratory burst response of surface-adhering leukocytes, thus interfering with major regulatory functions of cells also in surrounding tissues. The respiratory burst of surface-adhering leukocytes may thus be a key event in the understanding of biomaterial interaction with tissues, and the aim of this review is to highlight this field of research.

Surface-adhering Human Leucocytes: An In Vitro Model for Cytotoxicity Testing of Fluids.

A rapid screening method was developed for assessment of the toxic effects of fluid materials on the respiratory burst response of polymorphonuclear neutrophils (PMNLs). The method was used to detect adverse effects of peritoneal dialysis (PD) fluids. Intoxication of the respiratory burst response attenuates the bacterial killing capacity of PMNLs, and increases the sensitivity of patients to peritoneal infection. Capillary blood was taken from healthy donors, placed in drops on commercially available titanium pieces, and incubated in a humidified chamber at 37°C for up to 1 hour. The blood was rinsed off with saline, and the adhering cells were characterised by immunofluorescence by using antibodies directed against specific cell-differentiation antigens. A majority (> 95%) of the adhering leucocytes were PMNLs. The surface expression of selectins was down-regulated after 30 minutes, and the expression of integrins was down-regulated after blood exposure for 1 hour. NADPH-oxidase activity of the adhering cells was stimulated by f-MLP peptide and by opsonised zymosan. The zymosan-induced activation showed a lag-phase after 1 hour, consistent with the down-regulated expression of integrin. The zymosan-stimulated enzyme activity was used as an indicator of the cytotoxicity of PD fluids. NADPH-oxidase activity was inhibited by PD fluids with a pH of 5.7 and by heat-sterilised PD fluids. The results were compared with data obtained by using isolated circulating cells and cells from peritoneal dwell fluid.