Intercellular contact and the radiation response of cells of human melanoma xenografts.

Cells from two human melanoma xenografts (E.E. and V.N.) were irradiated at various times up to 24 hours after dispersion of the tumors. The surviving fraction for cells exposed to 5.0 (E.E.) and 4.0 Gy (V.N.) did not change with time, and was not significantly different for cells kept at 4 degrees C and 37 degrees C in the time interval between tumor dispersion and irradiation. The complete survival curves for cells irradiated 1.5, 6, 12, and 24 hours (E.E.) and 1.5, 6, and 18 hours (V.N.) after tumor dispersion were not significantly different. It is concluded that an intercellular contact effect similar to that reported for V79 Chinese hamster spheroids and murine KHT sarcomas is not present for E.E. and V.N. human melanoma xenografts.