Background: Airway inflammation, acknowledged as an important feature of asthma, can be assessed by the examination of induced sputum. Objective: To determine the pattern of inflammatory cells in induced sputum from stable steroid-naïve asthmatics, in Florianópolis, Santa Catarina. Method: The induced sputum from 34 asthmatics using exclusively inhaled bronchodilators on demand was examined. The patients' clinical characteristics were obtained at visit 1, and sputum was induced at visit 2. Differential cell count was performed on Giemsa-stained cytospins. Sputum was considered to be eosinophilic if there were ³ 3% eosinophils, and neutrophilic if there were ³ 65% neutrophils. Results: Results are expressed by median and interquartile range. The total cell count was 3.4 (3.7) x 106 cells/ml, and cell viability was 80.0 (16.4) %. The proportion of neutrophils was 14.4 (22.1) %, of eosinophils 6.4 (17.2) %, of macrophages 60.3 (37.5) %, and of lymphocytes 1.1 (1.2) %. Eosinophilic sputum was observed in 24 subjects (70.6%); none of them had neutrophilic sputum. There were no significant differences between the eosinophilic and non-eosinophilic groups concerning the measured clinical outcomes, total cell count and proportions of cells in the sputum, except for the proportion of eosinophils (14.4 [19.3] vs 0.4 [1.1], p < 0.001). Conclusions: In our environment, steroid-naïve asthmatics present a higher proportion of sputum eosinophils, as compared to the established reference values. The clinical and physiological parameters analyzed were unable to predict the presence of eosinophilic inflammation of the airways.

Keywords: Asthma. Inflammation. Sputum. Eosinophils. Neutrophils.

Objective: To determine the reliability of a rapid hematology stain for the cytological analysis of induced sputum samples. Methods: This was a cross-sectional study comparing the standard technique (May-Grünwald-Giemsa stain) with a rapid hematology stain (Diff-Quik). Of the 50 subjects included in the study, 21 had asthma, 19 had COPD, and 10 were healthy (controls). From the induced sputum samples collected, we prepared four slides: two were stained with May-Grünwald-Giemsa, and two were stained with Diff-Quik. The slides were read independently by two trained researchers blinded to the identification of the slides. The reliability for cell counting using the two techniques was evaluated by determining the intraclass correlation coefficients (ICCs) for intraobserver and interobserver agreement. Agreement in the identification of neutrophilic and eosinophilic sputum between the observers and between the stains was evaluated with kappa statistics. Results: In our comparison of the two staining techniques, the ICCs indicated almost perfect interobserver agreement for neutrophil, eosinophil, and macrophage counts (ICC: 0.98-1.00), as well as substantial agreement for lymphocyte counts (ICC: 0.76-0.83). Intraobserver agreement was almost perfect for neutrophil, eosinophil, and macrophage counts (ICC: 0.96-0.99), whereas it was moderate to substantial for lymphocyte counts (ICC = 0.65 and 0.75 for the two observers, respectively). Interobserver agreement for the identification of eosinophilic and neutrophilic sputum using the two techniques ranged from substantial to almost perfect (kappa range: 0.91-1.00). Conclusions: The use of Diff-Quik can be considered a reliable alternative for the processing of sputum samples.

Keywords: Sputum\analysis; Sputum\cytology; Azure stains.