Dynamics of tumor growth in Brattleboro and WAG rats injected with Walker 256 carcinosarcoma cells in different doses

The peculiarities of Walker 256 tumor growth depending on the dose of transplanted cells were studied in rats differing by vasopressin production. Transplantation of 105 cells does not lead to tumor development. The dose of 7×105 cells induces progressively growing tumors in WAG rats, while in Brattleboro rats tumors regressed after a short period of growth. Increasing the dose to 2.8×106 cells was inessential for the dynamics of tumor growth in WAG rats, but stimulated regression of tumor growth in Brattleboro rats, producing no vasopressin. This dose dependence suggests the involvement of the immune system into the dynamics of tumor growth.