Latent Period and Antigenicity of Murine Tumors Induced in C3H Mice by Short-Wavelength Ultraviolet Radiation

Abstract

Skin tumors were induced in C3H/HeNCr1BR mice with chronic short-wavelength ultraviolet (UVC) irradiation using a germicidal lamp (254 nm). Fifty percent of mice had developed tumors by 9 1/2 months (range 8-12 months). With progressive irradiation, mice developed multiple tumors on the back reaching a mean of 2.9 tumors/mouse at 11 1/2 months. No tumors developed on the ears. Of 83 lesions examined histologically 66 (80%) were squamous cell carcinomas, 6 (7%) were fibrosarcomas, and 10 (12%) were proliferative squamous lesions without evident invasion. Twenty-two squamous cell carcinomas were transplanted s.c. into normal syngeneic mice and into mice immunosuppressed by adult thymectomy, lethal x-irradiation, and bone marrow or neonatal liver reconstitution. Transplantation of squamous cell carcinomas was successful in a total of 17/22 (77%) cases. Only 11/22 (50%) tumors grew progressively in normal mice. Six of 22 (27%) tumors grew progressively in immunosuppressed mice but not normal syngeneic recipients. Three fibrosarcomas were also transplanted. All 3 grew progressively in immunosuppressed hosts but failed to grow in normal syngeneic recipients. Two fibrosarcomas that were induced by a germicidal lamp were found to grow significantly better in UVB-irradiated (280-320 nm) mice than in normal mice. Conversely, a UVB-induced fibrosarcoma showed enhanced growth in UVC-irradiated mice compared to growth in normal, age-matched controls.