Is there a role for measurement of nasal IgE antibodies in diagnosis of Alternaria-induced rhinitis in children?

BACKGROUND Rhinitis is a very common disease, frequently caused by sensitisation to inhalant allergens. Negative results from skin prick tests (SPT) and in vitro IgE tests generally lead to a diagnosis of non-allergic rhinitis. However, it is possible, as indicated by studies addressed with dust mites or pollens that the production of specific IgE occurs exclusively at nasal level. METHODS We measured specific nasal IgE in children suffering from rhinitis in the periods when Alternaria spores were present in the air. All subjects underwent SPT with a standard panel of aeroallergens (Stallergenes, Milan, Italy) and, in the same session, to nasal IgE test (NT). Nasal provocation test (NPT) with Alternaria was used as reference. RESULTS Fifty-six subjects were included in the study. Of them, 20 (37.5%) were positive to SPT and 45 (80.3%) were positive to NT. In particular, 11 subjects (19.6%) had a positive SPT and a negative NT; 36 (64.3%) had a negative SPT and a positive NT; and 9 (16.1%) were positive to both tests. Positivity of NT and NPT was observed in 36 patients (69.6%), while positivity of SPT and NPT was observed in 15 patients (26.8%). This difference was highly significant (p<0.0001). CONCLUSIONS These findings suggest that sensitisation to Alternaria is frequently expressed by exclusive production of specific IgE in the nasal mucosa. Thus, measuring nasal IgE in children with rhinitis and negative SPT during the period of presence of Alternaria spores seems helpful to avoid a mistaken diagnosis of non-allergic rhinitis.