title: Non-immunological enhancement of tumour transplantability in x-irradiated host animals.
abstract: MSC-10 tumour cells (derived from a chemically induced pulmonary squamous-cell carcinoma in DBA/2 mice) were inoculated intramuscularly into thymectomized, X-irradiated isogeneic mice, either 48 h or 6 weeks after thymectomy and X-irradiation. Normal mice and immunologically reconstituted mice served as controls. A marked enhancement in frequency of tumour takes was observed in all groups of animals inoculated with tumour cells 48 h after whole:-body X-irradiation, whether thymectomized, immunologically reconstituted or not. The TD50 decreased to less than 1/10 of that observed in unirradiated controls. When mice were inoculated with tumour cells 6 weeks after X-irradiation, the incidence of tumour takes was similar to that of unirradiated controls, including the thymectomized-irradiated group, which was still severely immunodeficient as measured by antibody formation and skin graft rejection. The experiments indicate that whole-body X-irradiation creates a condition that favours tumour cell survival or growth. This "permissive state" exists only shortly after X-irradiation and is not correlated with the host's level of immunocompetence.
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell; D006085:Graft Survival / Q000528:radiation effects*; D007111:Immunity, Cellular; D008297:Male; D051379:Mice; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental; D016038:Skin Transplantation; D013934:Thymectomy; D014184:Transplantation, Homologous; D014965:X-Rays