Abstract
We studied whether a streptococcal immunopotentiator, OK-432, could reactivate natural killer (NK) cell activity following the readministration of OK-432 in cancer patients.
Microassay methods were employed for a 5-hr51Cr release test using mononuclear cells separated from peripheral blood as effector cells and 51Cr-labeled K562 cells as target cells with an effectorto-target ratio of 20: 1.
In the patients before or after surgery, the first course of OK-432 strongly augmented the NK activity within three days after the initial administration of OK-432.
Enhanced cytotoxicity occurred with reintroduction of OK-432. But the maximum level was lower than that of the first course when the duration between the first and second course of OK-432 administration was short, whereas the maximum level of cytotoxicity was high and almost same as that of the first course when the duration was long.
