Matteo Gelardi, Mariangela Bosoni, Marco Morelli, Silvia Beretta, Cristoforo Incorvaia, Serena Buttafava, Massimo Landi, Simonetta Masieri, Franco Frati, Nicola Quaranta, Gian Vincenzo Zuccotti

In patients polysensitized to pollen allergens, the priming effect, by which the sensitivity of the nasal mucosa to an allergen is increased by the previous exposure to another allergen, is a known phenomenon. This study was aimed at evaluating the degree of nasal inflammation, assessed by nasal cytology, in children with allergic rhinitis (AR) from ragweed pollen according to being monosensitized or polysensitized. The study included 47 children. Of them, 24 suffered from AR caused by sensitization to grass pollen and ragweed pollen (group A) and 23 were sensitized only to ragweed pollen (group B). In all patients, the severity of AR was assessed according to the Allergic Rhinitis and Its Impact on Asthma guidelines, and comorbidities were also evaluated. In group A, 16.7% of children had a mild intermittent AR, 4.2% a moderate-to-severe intermittent, 33.3% a mild persistent, and 45.8% a moderate-to-severe persistent; in group B, 26.1% of children had a mild intermittent AR, 0% a moderate-to-severe intermittent, 52.2% a mild persistent, and 21.7% a moderate-to-severe persistent. No significant difference was detected in the number of the considered comorbidities between the two groups. The cell counts of neutrophils, eosinophils, lymphocytes/plasma cells, and mast cells were high but not significantly different in the two groups. These findings show that the degree of nasal inflammation found in children with ragweed-induced AR is not influenced by additional allergy to grass pollen and confirm the previously reported absence of priming effect in ragweed allergy.