The Effect of Irradiated Feeder Cells on the X-Ray Survival Curve Shape of Freshly Explanted Human Tumor Cells and a Standard Human Tumor Cell Line

Abstract

Curves for the survival of reproductive capacity in vitro were obtained for freshly explanted human tumor cells and the standard human tumor cell line HeLa ${\rm S}\text{-}3_{{\rm oxf}}$ following X irradiation. The results suggest that preirradiated feeder cells have a more significant effect at doses of about 700-900 rad (in terms of increased survival of an initially viable irradiated test cell population) than effective feeder cells produced in the test cell population. A direct effect of using irradiated feeder cells is an increase in the size of the shoulder as measured by $D_{{\rm q}}$ and an increase in the gradient of the high-dose region of the survival curve.