Do tryptase, ECP and specific IgE measurement by nasal incubation increase the specific nasal provocation test sensitivity?

Abstract

The specific Nasal Provocation Test (sNPT) is a third level diagnostic tool. Fitted to reproduce natural exposure condition to pick the responsible allergen for nasal symptoms out, it is applied when prick test and RAST responses are doubtful. SNPT results have been evaluated measuring nasal resistance (anterior rhinomanometry) and nasal symptoms (clinical score), reaching 50% of sensitivity. This study focused on the determination of allergic response markers, triggered by nasal challenge: tryptase levels in the nose, specific IgE and ECP (Eosinophil Cationic Protein). The aim was to increase sNPT sensitivity. Twenty patients suffering from allergic rhinitis and 16 age-matched-nonallergic subjects were enrolled in the study. Tryptase, specific IgE and ECP were determined in nasal mucosa applying a new method, based on in situ incubation, before and after sNPT. The latter was performed following a standardized method. Tryptase levels increased in 13 patients (65%), were unchanged in four patients (20%), and slightly decreased in three patients (15%). The increase recorded was significant in mite allergic patients (p=0.005), but not significant (p> 0.05) in pollen allergic patients. ECP values increased in 13 patients (65%), were unchanged in two patients (10%), and highly decreased in five patients (25%). ECP increase was not significant (p> 0.05). Specific IgE levels increased in seven patients (35%), were unchanged in 11 patients (55%) and decreased in two patients (10%). The IgE increase was significant in pollen-allergic patients (p<0.05), while it was not significant in mite-allergic patients (p>0.05). Tryptase, ECP, and specific IgE were not detected in the control group. The data obtained showed a positive sNPT response in 12 patients (60%). Comparing our results with those derived from classical-parameter employment, we gathered an improvement of 10%. On the basis of the usual parameters, in fact, we recorded 50% positivity, while the use of mediators provided an additional 10% improvement in sNPT sensitivity: taking together the usual parameters and nasal allergic mediators values, we reached an sNPT over-all sensitivity of 85%.