NASAL IMMUNOTHERAPY IN WEED-INDUCED ALLERGIC RHINITIS

Background: Nasal immunotherapy with single allergen extracts, followi ng premedication with cromolyn, has been reported to be effective in t reating seasonal and perennial allergic rhinitis. Methods: We conducte d a double-blind, placebo-controlled study to assess the efficacy, tol erability, and mechanism of action of nasal immunotherapy for allergic rhinitis caused by weed pollens from three unrelated families. Twenty -seven weed-allergic patients underwent baseline nasal provocation and titrated skin test with a mixed weed extract containing ragweed, sage , and Chenopod extracts. Patients were randomized to receive either mi xed weed extract or placebo. Nasal immunotherapy was self-administered daily to alternate nostrils preceded by 5.2 mg intranasal cromolyn. B eginning with 1:2500 wt/vol the concentration was increased to 1:10 wt /vol over an average period of 36 days. The maintenance dose (1:10 wt/ vol) was administered daily for 12 to 16 weeks through the weed pollen season, Patient: recorded nasal and eye symptoms and the use of rescu e medications throughout the study. A nasal lavage for cytokine levels and nasal scraping with Rhinoprobe for nasal cytology were performed at the peak of the weed season. Nasal provocation and titrated skin te sts with mixed weed extract were repeated after the weed season. Nasal lavage and scraping were also performed before and 24 hours after the final nasal provocation, Results: During the peak weeks of the weed s eason the group receiving mixed weed extract by nasal instillation, co mpared with those treated with placebo, had significantly lower total nasal symptom scores, total eye symptom scores, and symptom medication scores. There were no significant differences in the nasal cytology o r cytokines levels between the two groups, except for elevated IL-10 i n the nasal lavage in the treated group at the peak of the season. Nas al symptoms and medication use were higher preseasonally in the active treatment group. Conclusion: Nasal immunotherapy with aqueous mixed w eed extract administered with cromolyn sodium pretreatment for 17 to 2 1 weeks was effective in reducing both nasal and ocular symptoms of we ed pollen-induced allergic rhinitis. There were increased nasal sympto ms in the treated group preseasonally.