Factors that affect the allergic rhinitis response to ragweed allergen exposure.

BACKGROUND: People with seasonal allergic rhinitis (SAR) respond to allergen exposure differently.
OBJECTIVE: To determine the factors that affect the rate and degree of symptom development upon controlled allergen exposure.
METHODS: Study participants underwent skin prick testing (SPT) to selected aeroallergens, completed the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) and the 36-Item Short Form Health Survey, and provided a detailed allergy and exposure history. Nasal eosinophil counts and late-phase responses to SPT were measured. Eligible participants underwent a 3-hour ragweed pollen exposure in the Environmental Exposure Unit, rating rhinoconjunctivitis symptoms every 30 minutes. Data were analyzed using a mixed-effects model for repeated measures.
RESULTS: One hundred twenty-three participants completed the study. Skin test reactivity to ragweed was not correlated with the rate of symptom development or with severity. Participants with positive SPT reactions to dust mite, dog, or grass and those with self-reported symptoms to dog or cat exposure tended to develop symptoms earlier and to a greater degree by 90 minutes. Self-report of SAR symptoms during the ragweed or grass season and RQLQ scores were positively associated with the rate and degree of symptom development. No other significant associations were detected.
CONCLUSIONS: The rate of symptom development upon ragweed exposure was related to concomitant hypersensitivity to perennial allergens and grass pollen as determined by SPT and clinical history. The RQLQ was a powerful predictor of the priming response to ragweed, showing a dose-response-type association. These data suggest that a "prepriming" phenomenon is present in patients with SAR. No correlation was shown between symptomatic responses and degree of SPT reactivity.