Leukemia Induced by 7 ,12-Dimethylbenz[a]anthracene in Germfree Rats2

Abstract

Lobund germfree and conventional Sprague-Dawley, Fischer, and Wistar rats were inoculated repeatedly with 7,12-dimethylbenz[a]-anthracene (DMBA) in Fat. The rats that survived the toxic effects of the DMBA developed myelogenous leukemia, breast tumors, and carcinomas of the ear canal. The primary transformation to leukemia was associated with a depletion of cells in the spleen and, subsequently, the appearance of expanding masses of anaplastic lymphoid cells in the red pulp. Thereafter, leukemic cells appeared in liver and adrenal tissues. The disease was induced in newborn rats by cells derived from leukemic organs. Germfree rats with DMBA-induced myelogenous leukemia, adenocarcinomas of the breast, and carcinomas of the ear canal were examined extensively for evidence of virus, but none was found.