Immunological induction of flavor aversion in mice

ABSTRACT

1. Young adult BALB/c and B6D2F1 mice of both sexes (20 +/- 2 g) immunized ip with 2 doses of 10 micrograms ovalbumin (Ova), but not with 2 doses of 10 micrograms bovine gammaglobulins (BGG), show aversion to the ingestion of sweetened egg white or crystallized Ova solutions which are avidly ingested by normal mice. In 24 h, normal mice or mice immunized with BGG ingested, respectively, 340 +/- 80 and 265 +/- 56 mg of sweetened egg white per gram of body weight (mg/gbw); in the same period, Ova-immunized mice ingested less than one tenth these amounts (18 +/- 5 mg/gbw). ELISA-titers of anti-Ova and anti-BGG antibodies in immune mice were of similar magnitude. 2. Aversion arises coincidentally with the emergence of anti-ovalbumin antibodies in serum in the primary response, 14 days after primary immunization. 3. Previous induction of oral tolerance to ovalbumin by a single gavage with 20 mg Ova 7 days before primary ip immunization, which blocks the increase of specific antibodies in serum, also blocks the development of the aversive phenomenon. 4. Aversion was induced to 1 mg/ml but not 0.1 mg/ml sweetened crystallized ovalbumin solutions and was already noticeable 2 h after exposure of immunized mice to sweetened egg white solutions. 5. We conclude that, at least in experimental situations, immunological factors may be of decisive importance in diet selection.