Changes in resistance to tumor development in various strains of mice exposed to immunologic agents during the neonatal period

: In the course of exposures to the immunological agents (BCG, complete Freund's adjuvant) during the postnatal period, the resistance to tumor development induced with chemical carcinogens was found to increase in C57BL/6 mice, particularly in BALB/c and random-bred ones; meanwhile in C3H/He mice it declined. At the same time C3H/He mice showed a decrease in the resistance to the development of spontaneous tumors of the mammary glands. The changes recorded correlated with those seen in the immunocompetent organs.