Nasal eosinophils display the best correlation with symptoms, pulmonary function and inflammation in allergic...

The pathogenesis of allergic rhinitis and its link with asthma are well known. Nevertheless, a complete cross-sectional evaluation of the usually available clinical, functional and immunological parameters has never been made. We assessed nasal symptoms and flow, cytology, cytokines, pulmonary function and methacholine positivity in a large number of patients with pure pollinosis.

Young men presenting at a military hospital for routine follow-up were recruited for the study. They had to suffer from rhinitis alone (without asthma) for at least 2 years and had to have a positive skin prick test to pollens only. During the pollen season, they underwent symptom evaluation, measurement of nasal flow, nasal scraping and lavage (cell count and assay for IL-4, IL-5, IL-8 and IFNgamma), pulmonary function tests and methacholine challenge.

Fifty subjects (23.7+/-4.9 years old) were enrolled. All patients had high clinical scores (9.5+/-1.6) and inflammatory cells (eosinophils: 10.5+/-4 and neutrophils 21.3+/-6) and low nasal flow (482+/-111 ml/s). We found that the number of eosinophils in nasal scrapings highly correlated with all the above-mentioned parameters, including nasal flow, cytokines and spirometric values. A significant positive correlation was found between all inflammatory cells and all cytokines. IL-8, IL-4 and neutrophils displayed only a partial correlation with pulmonary parameters (FEV1, FVC and FEF25-75%), at variance wit IL-5 and eosinophils. Methacholine test positivity significantly correlated with the number of eosinophils in the nasal smear.

Eosinophils in the nasal smear display the best correlation with all the clinical and immunological parameters in allergic rhinitis and also correlate well with methacholine response.