title: Effects of whole-body irradiation on neonatally thymectomized mice. Incidence of benign and malignant tumors.
abstract: The individual and combined effects of neonatal thymectomy and whole-body irradiation on the prevalence of benign and malignant tumors in germ-free female mice of the Charles Rivers line were studied to determine if a portion of the tumorigenic effects of irradiation can be attributed to injury of the thymic-dependent component of the immune response. Neonatal thymectomy increased a) the incidence of benign and malignant tumors and b) the prevalence of multiple primary neoplasms in an individual mouse. Whole-body exposure to 700 rad at 6 weeks of age further increased th incidence of tumors, but the relative magnitude of this increase was less pronounced than in sham-operated controls. Thus, the cumulative effects of thymectomy plus irradiation are less pronounced than the sum of the individual effects. One of several possible explanations for this observation is that a portion of the carcinogenic effects of whole-body irradiation is mediated by suppression of the thymic-dependent component of the immune response.
mesh_terms: D000818:Animals; D005260:Female; D051379:Mice; D009369:Neoplasms / Q000209:etiology*; D009378:Neoplasms, Multiple Primary / Q000209:etiology*; D011829:Radiation Dosage; D011839:Radiation, Ionizing / Q000009:adverse effects*; D013934:Thymectomy; D013950:Thymus Gland / Q000502:physiology*