Nasal Histamine Reactivity; Relationships to Skin-test Responses, Allergen Provocation and Symptom Severity in Patients with Long-continuing Allergic Rhinitis

It has been reported that skin-test reactivity and rhinitis symptom severity weaken in the course of time. A corresponding weakening might also be seen in non-specific nasal hyper-reactivity, but the relationships of these responses are poorly understood. Our aim was to measure nasal responsiveness to histamine in a series of patients with long-continuing allergic rhinitis and to compare these measurements with skin test responses, allergen provocation and changes in severity of allergic rhinitis symptoms. A total of 73 patients in whom allergic rhinitis had been verified over 20 years earlier were re-interviewed and re-investigated. Skin prick tests with common allergens were performed and the presence of nasal allergy was confirmed by allergen provocation. Non-specific nasal hyper-reactivity was determined with nasal histamine challenge using four concentrations of histamine phosphate. The response was registered by counting sneezes, recording changes in nasal discharge and mucosal swelling and measuring nasal airway resistance. Sneezing and discharge scores showed that milder non-specific nasal hyper-reactivity was associated with lack of reactivity in skin prick tests and nasal allergen challenge. No association was observed between allergy test results and changes in nasal airway resistance during the histamine provocation. In most patients the symptoms of rhinitis had become milder or disappeared during the follow-up, but the results of the histamine challenge showed no relationship with the changes in symptom severity. In patients with allergic rhinitis, reactivity to histamine is associated with a concomitant change in skin and nasal mucosal reactivity to allergens.