Antigen-induced eustachian tube obstruction: an intranasal provocative challenge test

ETO and symptoms of AR have been demonstrated to develop after an intranasal provocative antigen-challenge test. To determine the antigen dose required to produce ETO, intranasal insufflations of increasing amounts of pollen (ragweed or timothy) from 0.1 to 100 mg were delivered to 29 patients, ages 20 to 31 yr with AR who were skin test positive or had elevated serum-IgE antibodies to ragweed or timothy but not pine pollen. Our results demonstrated ETO developed in four ears at 0.05 mg of pollen, in one at 0.5 mg, in four at 1 mg, in 28 at 10 mg, in 15 at 50 mg, and in two at 100 mg of pollen. ETO persisted from 2 to 120 hr. Dose responses and duration of ETO were compared to patients' serum-IgE antibodies that ranged from 3% to 36% B/T (median 26.4%). The patients with the highest serum-IgE antibody values (greater than or equal to 26.4%) required lower antigen-dose challenges (less than or equal to 10 mg) to develop ETO (p less than or equal to 0.01) that also persisted longer (less than or equal to 48 hr) p less than or equal to 0.05. Symptoms of AR developed with an antigen dose that was less than the antigen dose that resulted in the development of ETO in 22 patients and at the same antigen dose in the other seven subjects. At a later date, these same subjects were also challenged intranasally with 50 mg of pine pollen after which no symptoms of AR or development of ETO were noted. In summary, the expression of ETO after provocative intranasal pollen challenge in AR patients is an immune-mediated reaction that is antigen-dose dependent and related to serum-IgE antibody titer.