Enhancement of tumor growth following immunization with Bacillus Calmette-Guérin cell walls.

The effect of preimmunization with Bacillus Calmette-Guerin cell walls (BCGcw) on tumor growth was studied with the use of transplantable Morris Hepatoma 3924a in inbred ACl rats. There was an increase in tumor incidence, an increase in the i.m. tumor growth rate, and an increase in the average i.m. tumor mass in animals that were preimmunized with BCGcw. The BCGcw-induced enhancement in tumor growth was dependent upon the amount of tumor present at the time of BCGcw immunization. No enhancement occurred in animals immunized with BCGcw 12 days after the inoculation of tumor cells.