Inducibility of thymic lymphomas in female Hsd: (ICR)BR mice following subcutaneous injection of ethyl- and isopropyl methanesulfonate

Abstract

Isopropyl methanesulfonate (IMS), a direct-acting S N1 alkylating agent, induced thymic lymphomas in 29 of 30 female Hsd: (ICR)BR mice by the 139th day following once a week subcutaneous injections at a dose of 10 μmol/mouse. No such neoplasms were observed at the 450th day following 52 once a week subcutaneous injections (20 μmol/mouse) of the borderline S N1/S N2 alkylating agent ethyl methanesulfonate (EMS). Local sarcomas were observed in 2 and pulmonary adenomas in 20 of the 30 EMS-treated mice, 70% of which were alive at the 450th day. Neoplasms were not observed at local or at distant sites other than the thymus gland following treatment with IMS. The results suggest a sensitivity of hemopoietic tissue to the types of DNA lesions induced by IMS.