Influence of Neonatal Thymectomy on the Development of Primary Rous Sarcomas in two Inbred Strains of Rats*

Abstract

In a number of experimental systems it has been shown, that neonatal thymectomy
renders the animals more susceptible to the action of oncogenic viruses - polyoma virus
in mice (7) and rats (10), SV 40 virus in rats (2), Rous sarcoma virus in chidtens (8).
Tumour specific transplantation antigens have been demonstrated in mice (5) and in
rats (4) carrying sarcomas induced by Rous sarcoma virus of the Schmidt-Ruppin
strain (RSV-SR). It was the aim of the present investigation to study the role of the
immunologic impairment following neonatal thymectomy for the course of development
of primary sarcomas induced by RSV-SR in two inbred strains of rats.
In the search for suitable experimental animals five strains of rats were studied in
advance for the effect of neonatal thymectomy upon their lymphoid tissue and their
immunological capacity (3); neonatally thymectomized and sham-operated rats were
immunized with sheep red blood cells when adult, and their haemolysin titers measured;
also the cell content of particular lymph nodes was determined. A significant reduction
in haemolysin titers and of cell counts of lymph nodes in the groups of neonatally
thymectomized animals as compared with their sham-operated litter mates was observed
in the inbred Wistar/Fu (W/Fu) and Bladt/Norway (BIN) strains of rats. Therefore
these two strains were selected for the present long term experiment.