Mice allografted with different sarcomas, induced by the Schmidt-Ruppin variant of Rous sarcoma virus (RSV-SR), showed a resistance against subsequent isografting of 9 different Rous sarcomas. Transplantation resistance could also be induced by Rous mouse tumor cells x-irradiated with 8000 r or with cell-free tumor extracts, containing no demonstrable virus. No transplantation resistance could be demonstrated after allograft pretreatment with various polyoma tumors or non-viral tumors. Allograft pretreatment with Rous tumors induced no demonstrable resistance against isografting of polyoma tumors. Inoculation of RSV-SR or Rous chicken sarcoma suspension into adult mice gave no clear cut resistance against isografting of mouse sarcomas. Neither after allografting of Rous tumors nor after virus or chicken sarcoma inoculation into adult mice could virus-neutralizing activity be demonstrated in the sera.
The results demonstrate the presence of common, specific transplantation antigen(s) in different Rous sarcomas in mice and speak against an identity between the transplantation antigen(s) and viral antigen(s).