Accelerated Development of Transplanted Mammary Tumors in Mice Pretreated With the Methanol Extraction Residue of BCG and Prevention of Acceleration by Concomitant Specific Immunization

Abstract

Pretreatment of mice with the methanol extraction residue (MER) of BCG 14 and 3 days before challenge with syngeneic MTV+ mammary tumors resulted in an increased incidence of tumors compared with that in the saline-treated controls. When the animals were treated with MER several weeks before tumor challenge, tumor development was also accelerated. Faster tumor development did not seem related to the immunogenicity of these tumors, since acceleration was noted in syngeneic BALB/cfC3H (MTV+) mice in which these tumors were not detectably immunogenic, and also in syngeneic BALB/c (MTV-) hosts in which the tumors were strongly immunogenic. When MER treatment of either MTV+ or MTV- hosts was combined with specific tumor immunization, more rapid development of the challenge tumors did not occur, but there appeared to be no added beneficial effect of the combined treatment over immunization alone.