Visualization of oxidative processes at the cellular level during neutrophil‐mediated cytotoxicity against a human hepatoma cell line, HCC‐M

Human neutrophil‐mediated oxidative processes against a human hepatoma cell line, HCC‐M, was visualized at the cellular level by using a silicon‐intensified target camera and subsequently processing with a computer‐assisted digital‐imaging processor. Neutrophils were activated by a streptococcal preparation, OK‐432. A hydroperoxide‐sensitive tracer, dichlorofluorescin diacetate, was loaded in HCC‐M and temporal and spatial changes of lipid peroxides in this cell after addition of stimulated neutrophils were analyzed. The luminol‐dependent chemiluminescence activity of neutrophils was significantly enhanced and continued for at least 2 hr by stimulation with OK‐432, and its activity was shown to be accumulated at the site where a neutrophil attached with HCC‐M. The intensity of dichlorofluorescein fluorescence in HCC‐M rapidly increased after adding stimulated neutrophils, and their reaction was significantly attenuated by superoxide dismutase. The number of non‐viable cells was increased as the dichlorofluorescein fluorescence increased. It is suggested that oxidative stress may play an important role in neutrophil‐mediated tumor‐cell damage.