SYSTEMIC IMMUNE-RESPONSE AFTER RECTOCOLONIC ADMINISTRATION OF OVALBUMIN IN MICE

The aim of our study was to determine the effect of a rectocolonic pre immunization with ovalbumin on the systemic immune response induced by a subsequent subcutaneous injection of this antigen in Balb/c mice. O ne rectocolonic, but not intragastric, administration of 25 mg of oval bumin induced a detectable increase in serum anti-ovalbumin antibody l evel. The level reached was however much lower than after subcutaneous injection. Both intragastric and rectocolonic immunization with ovalb umin induced specific systemic cellular tolerance. However, after rect ocolonic, but not intragastric, preimmunization there was no systemic humoral tolerance to this antigen. These differences in systemic immun e responses after rectocolonic or intragastric administration of ovalb umin could be due to different stimulation of the systemic immune syst em or to differences between the colonic and small bowel mucosal immun e system, which remain to be elucidated.