Decreased resistance of C3H/HeHa mice to C3HBA tumor transplants; increased resistance due to supplemental vitamin A.

Groups of inbred C3H/HeHa and C3H/HeJ mice were inoculated with either a low or a high number of C3HBA tumor cells, C3H/HeHa mice were less resistant to tumor development and growth than C3H/HeJ mice as judged by tumor incidence, latent period, tumor size (growth rate), and survival time. Resistance to decrease and death following inoculation with tumor cells was related to thymus status in the following way: Thymic involution was associated with decreased resistance of the mice to tumor development. When C3H/HeHa mice were fed supplemental vitamin A, and treatment that increases their thymus size and numbers of thymic small lymphocytes, their resistance to the C3HBA tumor was markedly increased.