Abstract
It was demonstrated by electronmicroscopy and by the determination of enzymic activity in the mesenteric perfusate that horseradish peroxidase (HRP) was absorbed from adult rat intestine. When 1200 units of HRP was infused into the intestinal lumen of normal rats, 2.8 units of the enzyme was recovered in the mesenteric perfusate collected for 90 min. On the other hand, the absorption of HRP decreased specifically in rats immunized with HRP. In an in vitro experiment using everted gut sac, the effect of intraperitoneal immunization (three times) on HRP influx was 2-to 3-fold greater than that of subcutaneous immunization (six times). Although the influx was unchanged in the rats injected subcutaneously three times, the recovery of HRP in the perfusate after the same sensitization decreased significantly compared with the control rats. These results suggest that the absorption of antigen decreases after active sensitization and that the effect of immunization on the intestinal absorption depends on the administration route of antigen.
