ELEVATED PRODUCTION OF ACTIVE OXYGEN IN BLOOMS SYNDROME CELL-LINES

Based on our previous evidence indicating that the elevated sister chr omatid exchange that characterizes Bloom syndrome (BS) cells may arise in response to elevated production of active oxygen, we have quantita ted the levels of active oxygen in two control, two BS and one BS reve rtant cell lines. Luminol-dependent chemiluminescence was used as a me asure of active oxygen production following treatment of the cells wit h the calcium ionophore A23187 or the chemotactic tripeptide N-formylm ethionylleucylphenylalanine. A peptide factor present in plasma was re quired for priming the cells to undergo the oxidative response. As det ermined with A23187, active oxygen production was elevated in BS cell lines by 48.6% above control. Using N-formylmethionylleucylphenylalani ne, active oxygen production was found to be increased by 250-314%. Ch emiluminescence was inhibited in a dose-dependent manner by diphenylen e iodonium, which specifically binds to and inhibits membrane-associat ed NADPH oxidase activity. This compound inhibited oxygen radical prod uction nearly 3 times more effectively in control cells than in BS cel ls. The capacity to produce elevated levels of oxygen radicals may con tribute to the spontaneous chromosomal instability of BS cells and to the associated high incidence of neoplasia in individuals with BS.