Eosinophil count in nasal secretions of subjects with and without nasal symptoms

The aim of this paper, based on a cross-sectional study of 129 patients wit h nonallergic chronic nasal symptoms and 40 healthy controls, was to examin e the leucocyte differential count in nasal secretions as a diagnostic test . Nasal secretions were collected using preweighed suction glass canulas un der controlled conditions (-100Pa, 30 sec). Leucocyte and differential coun ts were performed using a Thoma hemocytometer and on cytospin slides after May-Grunwald-Giemsa staining The percentage of eosinophils eosinophils (Eo) was significantly higher in patients (mean+/-SEM: 15.1+/-2.3%) than in con trols (5+/-2.6%) (p<0.04). Comparison of the frequency distribution of the percentage of Eo in patients and controls clearly showed a subgroup of pati ents presenting with nasal secretion hypereosinophilia, and allowed us to s et the positivity criterion at Eo=20%. Diurnal variations in Eo count in 11 controls and 8 patients confirmed the value of the cutoff point. In 28 pat ients with nasal polyposis who underwent surgery, a correlation was found b etween secretion and tissue eosinophelia (r=0.58, p=0.001). Patients with n asal secretion hypereosinophilia had no more leucocytes in their secretions than healthy controls, the increase in eosinophils being balanced by a dec rease in neutrophils. Inpatients without hypereosinophilia, the number of l eucocytes per milligram of secretion was four times higher (8672+/-2521) th an in the controls (2020+/-823) (p=0.06) (cut-off point = 2500 leu/mg). The se data show that the nasal cytogram can be modified either in qualitative or quantitative way, probably depending on the underlying inflammatory proc ess.