Ultraviolet Carcinogenesis in C₃H Athymic Nude Mice

Abstract

The induction of skin tumors by ultraviolet irradiation (UV) in C₃H mice and congenic C₃H nude mice was examined. Prior to UV-irradiation, C₃H nude mice were reconstituted with thymus grafts from C₃H mice. C₃H nude skin was grafted onto the backs of C₃H mice before UV treatment. UV-induced tumors were tested for antigenicity and were examined histologically. The probability of tumor development was similar for UV-irradiated C₃H nude mice, UV-irradiated C₃H nude mice reconstituted with thymus grafts and UV-irradiated C₃H mice grafted with C₃H nude skin. UV-irradiated C₃H mice had a longer latency period of tumor development than the other three treatment groups. The probability of tumor development was significantly (P < 0.0048) lower for the UV-irradiated C₃H mice when compared to the other UV-irradiated treatment groups. All UV-induced tumors in the study were squamous cell carcinomas. Tumors from all of the UV-irradiated treatment groups were antigenic. This study indicates that the differences in latency period and probability of tumor incidence in the nude mouse are due to intrinsic properties of the skin and not to the lack of a functioning thymus.