The Effect of Adult Thymectomy and Adult Splenectomy on the Production of Leukemia and Stomach Neoplasms in Mice by N-[4-(5-Nitro-2-furyl)-2-thiazolyl]acetamide¹

The effect of thymectomy and splenectomy at 3 to 4 weeks of age on the oncogenicity of N-[4-(5-nitro-2-furyl)-2-thiazolyl]acetamide was tested in female Swiss mice. The drug was administered at 0.1% for 14 weeks beginning when the mice were 5 weeks old; the mice were then placed on control diet until their death or until 35 or 45 weeks of age. Without thymectomy the incidence of lymphocytic leukemia was 26 of 27; in partial thymectomized mice, it was 7 of 7; and in totally thymectomized mice, it was 0 of 15. The incidences of forestomach papillomas in these three groups were 1 of 27, 0 of 7, and 12 of 15, respectively, with infiltrative and metastatic squamous cell carcinoma of the forestomach in three of the latter group. Thus, thymectomy appears to prevent the appearance of lymphocytic leukemia in mice fed N-[4-(5-nitro-2-furyl)-2-thiazolyl]acetamide but allows for a greater incidence and degree of malignancy of the forestomach neoplasms. Splenectomy and sham operations had no effect on the incidence of leukemia or forestomach neoplasms.