Influence of Immunosuppression and Immunorestoration on the Formation of Urethan-induced Lung Adenomas2

Abstract

Inbred SWR/J and randombred Swiss mice, given injections of antilymphocytic serum (ALS) for different periods of time, received a single dose of the carcinogen urethan. These mice had, along with symptoms of immune impairment, a significantly increased incidence of urethan-induced lung adenomas, as compared with controls treated with normal rabbit serum (NRS). When neonatally thymectomized, urethan-treated SWR/J mice were implanted repeatedly with syngeneic thymuses, their immunologic competence was restored. Also, their neoplastic response was reduced, the tumor incidence in these mice being similar to that of intact animals and significantly lower than that in thymectomized controls. It appears, therefore, that a) impairment of immunologic competence is accompanied by an increase in the neoplastic response to urethan, and b) this increased susceptibility to the carcinogen could be abolished when the immunologie capacity of the mice was restored.