The effect of intravenously injected Ehrlich ascites tumour cells in cycloheximide-treated mice.

An intravenous injection of 5 X 10(6) washed, viable Ehrlich ascites tumour cells given to mice 2 hr before, immediately before, or 2 hr after a dose of 60 microgram/g body weight of cycloheximide, results in such animals being either dead or moribund 48 hr later. No fatalities occur when a similar number of tumour cells are given 2 hr before or 2 hr after a dose of 30 microgram/g body weight of cycloheximide. Similarly, 5 X 10(6) tumour cells are well tolerated when given to mice 18 hr after 60 microgram/g cycloheximide. It is suggested that an undefined minimum level of recipient protein synthesis is required for maintenance of life in the presence of a challenge by 5 X 10(6) tumour cells. A minimum period (less than 6 hr) is needed for an irreversible illness to result from interaction of tumour cells with a recipient animal under the maximal influence of the 60 microgram/g dose of cycloheximide. The irreversible illness is not avoided by the use of tumour cells pretreated for 2 hr with 30 microgram/g of cycloheximide, nor is the outcome altered when both recipient and tumour cells are together subjected to a 60 microgram/g dose of cycloheximide.