FLUORESCENCE IMAGING OF REACTIVE OXYGEN METABOLITES GENERATED IN SINGLE MACROPHAGE CELLS (NR8383) UPON PHAGOCYTOSIS OF NATURAL ZEOLITE (ERIONITE) FIBERS

In this paper we address the phenomenon of reactive oxygen metabolite generation subsequent to phagocytosis of mineral fibers by macrophages . Natural erionite fibers were chosen because of their established tox icity. Macrophages (cell line NR8383) were loaded with the dye 5-(and 6)-carboxy-2',7'-dichlorodihydronuorescein diacetate and exposed to er ionite particles by centrifuging cells and fibers together to effect a dherence. Reactive oxygen metabolite generation was examined by monito ring the fluorescence of oxidized dye formed via the reaction with oxy gen species produced during phagocytosis. Individual cells were repeat edly scanned for up to 2 hr to monitor the evolution of this fluoresce nce. It was found that erionite-exposed cells had a mean total fluores cence of three times that of controls during the first 35 min, declini ng to two times that of controls at 35-60 min and about the same level as that of controls at 60-80 min. Ultrastructural studies of similarl y treated aliquots of cells showed marked variation in size and number s of the phagocytized particles. This study demonstrates that intracel lular oxidation can be monitored on a single cell basis over a period of time. Quantitative studies are in progress to establish the relatio nship between the phagocytized particulate load and the extent of fluo rescence.