A new collection method for the evaluation of nasal mucus proteins

Abstract

Background: Different sampling techniques for collecting nasal mucus have been used. The eosinophil and its granule toxin proteins, especially the eosinophil cationic protein (ECP), is an important inflammatory cell. Objective: In the healthy subjects (with no acute or chronic disease of the respiratory tract), no detailed quantitative data on mucus nasal proteins have been reported, so the aim of the study is to demonstrate a simple and reliable method for the collection of nasal mucus and for measuring nasal ECP. Methods: Our method consists in collecting two specimens of mucus from each nasal fossa, using a square of sterile pre‐humidified gauze, centrifuged at 2000 g for 20 min and stored at −20°C until tested. To evaluate the reproducibility of the technique, 30 healthy subjects were retested after 24 h. Results: The amounts of secretion gathered in the 89 collections did not show any statistical difference between the sexes. In the pooled subjects (n = 59), the mean levels of ECP were 108 ng/mL and 325 ng/g and total protein (TP) levels were 701 mg/dL and 2.5 mg/g (expressed in absolute concentration and concentration related to the weight in grams). In the classes, according to age, no statistical differences were found on analysis of the groups by: sex, recovery rate, and ECP and TP concentrations. The Reproducibility Index was very good for the recovery rate (0.78), ECP (ng/mL = 0.95, ng/g = 0.83) and TP (mg/dL = 0.89, mg/g = 0.76). Conclusion: With our method, the sample collections were taken with minimal stimulation of the mucosa and it was well tolerated by the subjects; the low known dilution factor is also adequate for analysing small quantities of mucus recovered, and the protein concentration can be measured as an absolute value.