The Dose-response Relationship of the Ehrlich Ascites Tumour

Abstract

THE work described in this paper was carried out as a preliminary study on the " viability" of Ehrlich ascites tumour cells. Several tests have been described, using stains, which purport to distinguish "viable" from "nonviable" cells. However Hoskins, Meynell and Sanders (1956), using the ascites form of the Krebs-2 carcinoma, have pointed out that the results of such tests are not clearly related to the ability of tumours to grow in susceptible hosts.It is plain that there are two factors involved in the production of tumours in animals following the inoculation of tumour cells. The first is the "viability" of the inoculated cells and the second the "susceptibility" of the host. Serial dilutions of a suspension of tumour cells may be inoculated into mice and the proportion developing tumours recorded and plotted against the dose or number of tumour cells inoculated. The resulting dose-response curve may provide information concerning the viability of the cells and the susceptibility of the host animals.The study of dose-response relationships has received most attention in the field of pharmacology where the material comprising the dose is not particulate in the ordinary sense and can theoretically be varied infinitely. In the application of such studies to viruses, recently reviewed by Isaacs (1957), the dose consists of a number of virus particles and results have indicated that the appropriate mathematical distribution is often provided by the Poisson or exponential model. The purpose of some of the work on viruses has been to determine what proportion of particles in a virus suspension are viable and whether a single viable particle can initiate infection. A difficulty frequently encountered in this field has been to obtain a reliable method of counting the total (viable and non-viable) number of particles in a particular preparation. This difficulty does not arise with suspensions of ascites tumour cells as these are easily counted in a haemocytometer. Therefore it seemed that a study of the dose-response relationship of an ascites tumour, along the lines described by virus workers, could provide valuable information concerning the viability of its constituent cells and should, therefore, be investigated. This paper describes the results obtained from the intraperitoneal inoculation of serial dilutions of Ehrlich ascites tumour cells into a strain of white mice.