Ectopia tímica cervical: una entidad poco frecuente / Cervical ectopic thymus: a rare condition

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Interruption of recently induced immune responses by oral administration of antigen.

Interest in oral tolerance has been renewed in the last few years as a possibility of intervention in human autoimmune diseases. An obstacle in this direction is that, although easily induced in animals virgin of contact with the antigen, oral tolerance becomes hard to induce in previously immunized animals. The present results show that there is an early period after primary immunization in which prolonged oral exposure to the antigen may arrest ongoing immune responses. Beyond this period, oral exposures to the antigen become ineffective and may actually boost immune responses. The end of the susceptible period coincides with the emergence of free specific antibodies in serum. However, the previous administration of purified anti-ovalbumin antibodies (40 micrograms) was unable to block the induction of oral tolerance to ovalbumin in normal mice.

Interruption of recently induced immune responses by oral administration of antigen

Interest in oral tolerance has been renewed in the last few years as a possibility of intervention in human autoimmume diseases. An obstacle in this direction in that, although easily induced in animals virgin of contact with the antigen, oral tolerance becomes hard to induce in previously immunized animals. The present results show that there is an early period after primary immunization in which prolonged oral exposure to the antigen may arrest ongoing immune responses. Beyond this period, oral exposures to the antigen become ineffective and may actually boost immune responses. The end of the susceptible period coincides with the emergence of free specific antibodies in serum. However, the previous administration of purified anti-ovalbumin antibodies (40 mug) was unable to block the induction of oral tolerance to ovalbumin in normal mice.

Immunological induction of flavour aversion in mice. II. Passive/adoptive transfer and pharmacological inhibition.

Mice immunized with ovalbumin develop a strong aversion to ingesting sweetened egg white dilutions or ovalbumin solutions. In immunized animals, gavage or voluntary ingestion of ovalbumin triggers an increase of vascular permeability in the intestine; pretreatment with a mixture of histamine and serotonin antagonists blocked this reaction, but not the aversion; dexamethasone inhibited both the aversion and the increase in permeability. The aversion was transferred to normal recipient mice with high-titre anti-Ova sera obtained with complete Freund's adjuvant, but not with lower-titre serum pools of mice immunized with the help of Al(OH)3 adjuvant. However, the aversion was also (adoptively) transferred with whole spleen cells from immune donors. This later condition is inefficient to transfer the formation of high titres of specific antibodies.

Immunological induction of flavor aversion in mice.

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.

Immunological induction of flavor aversion in mice

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.