Paradoxical effect of three-day thymectomy on sarcogenesis in the mouse with different dosages of methylcholanthrene.

Past studies have shown that thymectomy in the mouse at 3 days of age but not at birth or after 7 days produces, in later life, a variety of localized autoimmune lesions. In the present work, 3-day thymectomy facilitated subsequent sarcogenesis by low dosages of 3-methylcholanthrene but inhibited oncogenesis by a high dosage. If the presence of autoimmunity implies an increased antitumor immunity, it then follows that increased immunity facilitated low-dose sarcogenesis but inhibited sarcogenesis with a high dose.