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 n eutrophils (PMNLs). The method was used to detect adverse effects of perito neal dialysis (PD) fluids. Intoxication of the respiratory burst response a ttenuates the bacterial killing capacity of PMNLs, and increases the sensit ivity of patients to peritoneal infection. Capillary blood was taken from h ealthy donors, placed in drops on commercially available titanium pieces, a nd incubated in a humidified chamber at 37 degrees 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-d ifferentiation antigens. A majority (> 95%) of the adhering leucocytes were PMNLs. The surface expression of selectins was down-regulated after 30 min utes, and the expression of integrins was down-regulated after blood exposu re for 1 hour. NADPH-oxidase activity of the adhering cells was stimulated by f-MLP peptide and by opsonised zymosan. The zymosan-induced activation s howed a lag-phase after 1 hour, consistent with the down-regulated expressi on of integrin. The zymosan-stimulated enzyme activity was used as an indic ator 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 result s were compared with data obtained by using isolated circulating cells and cells from peritoneal dwell fluid.