The effect of in vitro irradiation on human NK cell activity. A preliminary report

Natural killer activity of peripheral blood cells was evaluated after in vitro irradiation at doses ranging between 100 and 1600 cGy. Natural killer (NK) cells from normal donors exhibited a trend towards increased cytotoxicity peaking at about 600 cGy and then gradually decreasing. NK cells isolated from peripheral blood of cancer patients showed a lower baseline of activity, which was less affected by the same doses of in vitro irradiation. A distinction could be made between patients with early disease and those with advanced cancers; patients with early cancers showing NK activity close to that of normal donors.