INDUCTION OF HUMORAL IMMUNITY TOWARD 2-ACETYLAMINOFLUORENE IN MICE - MODULATION OF DNA-BINDING AFTER 4 WEEKS DIETARY EXPOSURE TO THE CARCINOGEN

In order to investigate the modulatory effect of the immune response i nduced by recurrent carcinogen exposure, anti-2-acetylaminofluorene (a nti-2-AAF) IgG were elicited in Swiss mice before subsequent carcinoge n administration, The immunization schedule consisted of three weekly i.p. injections of 2-acetylaminofluorene (2-AAF)-gelatin conjugate, fo llowed by a final immunogen injection 14 days later. At the end of tre atment, the presence of specific anti-2-AAF antibodies in blood serum of all immunized animals was demonstrated, The immunization procedure did not affect liver metabolic activities, as evaluated using liver ho mogenates for the exogenous activation of 2-AAF to mutagen, After immu nization, mice were fed 2-AAF pelleted in the diet at 50 and 150 p.p.m . for 4 weeks and killed at the end of treatment, The determination of DNA adducts by ELISA in liver and spleen of treated animals revealed significantly (P < 0.01-0.001) lower 2-AAF adduct levels in both tissu es of immunized mice with respect to non-immunized animals (both naive and pretreated with the adjuvant alone). This result suggests that th e specific humoral immunity elicited by repeated carcinogen exposure m ay be able to modulate the genotoxic effect induced by subsequent carc inogen administration.