To determine the influence of local antigen exposure doses of Japanese cedar pollen on the sensitization and severity of hay fever, we examined three groups of Brown Norway rats. These consisted of a high exposure group, a lower exposure group and controls. In the high exposure group, the rats were exposed daily to 20μg Cry j I, one of the major allergens for Japanese cedar pollinosis, 5 days per week for 6 months pernasally. In the lower exposure group, the rats were exposed to 2μg Cry j I, and nil in the controls. After local exposure, these rats were immunized twice on day 0 and day 13 with intraperitoneal injections of 10μg Cry j I with 4.5mg aluminium hydroxide gel.
The serum levels of anti-Cry j I IgE antibodies were determined by the method of reverse IgE-capture enzyme-linked immunosorbent assay (ELISA). The mean value of the serum specific IgE level in the high exposure group was significantly higher than that in the low group.
The mean value of the serum specific IgE in the low group was significantly higher than that in the controls. The extent of the local eosinophilia of the nasal mucosa in the high group was significantly greater than that in the controls but not than that in the low group. The extent of the laryngeal eosinophilia in the high group was significantly greater than that in the low group on the controls.
Only small eosinophil accumulations were observed in the tracheal mucosa of the three groups.
