Immunological reaction to horseradish peroxidase of the palatine tonsil of the rabbit.

Detection of the immune response to external antigen of the palatine tonsil of the rabbit is an interesting problem. Employing horseradish peroxidase (HRP) as an external antigen, the reactions of a perfusion sensitized group and those of a group sensitized by intravenous injection were examined. The results were as follows: 1. Hypertrophy of the palatine tonsil was recognized only in the perfusion sensitized group. 2. The serum titer level of the antibody to HRP was recognized to be high in the intravenous injection sensitized group, which was confirmed by the production of antibody in the spleen. It was also confirmed in the repeated perfusion sensitized group at a low level. 3. Antigen invasion through the epithelium of the crypt was possible by repeated intravenous injection sensitization as for perfusion sensitization. Also, invading HRP was observed electron microscopically to be phagocytized by macrophages and dendritic reticular cells. 4. In the perfusion sensitized group, production of antibody was not found in the palatine tonsils but in the regional lymph nodes of the neck. 5. In the perfusion sensitized group, a large number of eosinophils were noted mainly on the basal side of the interfollicular zone. 6. In the intravenous injection sensitized group, anti-HRP was found in the palatine tonsils and also in the spleen. Participation of the tonsils has been revealed in general human immunity.