Local allergic asthma to cat allergens.

Background: Cat allergy is a well-established risk factor for developing allergic respiratory diseases. However, relying solely on the detection of systemic allergen-specific IgE may underestimate the true prevalence of these conditions. Objective: This study assessed asthmatic patients who exhibited symptoms triggered by cat allergen exposure but tested negative for systemic cat-specific IgE. Methods: Asthmatic patients (study group, SG) from a tertiary-care hospital, presenting symptoms induced by cat exposure but negative for systemic cat-specific IgE (skin prick test and Fel d 1 sIgE), underwent a nasal provocation test with cat extract. The procedure began with saline instillation, followed by 4 incremental dilutions of cat allergen extract, starting at 0.0024 μg/mL. At each stage, respiratory and skin symptoms were monitored, alongside spirometry, peak nasal inspiratory flow, and vital signs. Two control groups were included: one with patients diagnosed with cat-related respiratory allergy (AG) and another with patients without cat-related respiratory allergy. Results: All patients but one in the SG and all in the AG demonstrated positive responses to the cat allergen nasal provocation test, while the no-cat-allergy group showed no response. Delayed respiratory reactions were observed in 6.7% of SG and 10% of AG patients (bronchospasm), while nasal symptoms occurred in 33.3% of SG and 20% of AG patients. Conclusions: nasal provocation test with cat allergen extract is a valuable diagnostic tool for confirming local allergic asthma triggered by cat exposure. However, because of the potential for severe reactions, it should only be performed by trained personnel in an appropriate clinical setting.