Nasal histamine reactivity; Relationships to skin-test responses, allergenprovocation and symptom severity in patients with long-continuing allergicrhinitis

It has been reported that skin-test reactivity and rhinitis symptom severit y weaken in the course of time. A corresponding weakening might also be see n in non-specific nasal hyper-reactivity, but the relationships of these re sponses 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 provo cation 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 alle rgens were performed and the presence of nasal allergy was confirmed by all ergen 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 nasa l discharge and mucosal swelling and measuring nasal airway resistance. Sne ezing and discharge scores showed that milder non-specific nasal hyper-reac tivity was associated with lack of reactivity in skin prick tests and nasal allergen challenge. No association was observed between allergy test resul ts 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 allerg ic rhinitis, reactivity to histamine is associated with a concomitant chang e in skin and nasal mucosal reactivity to allergens.