ABSTRACT
Figure 6.4 Odds ratio (vertical bars show 95% confidence intervals) for the association between sputum eosinophils (top panel), sputum mast cells (bottom panel), and asthma symptoms (p < 0.05), airway hyperresponsiveness (AHR) (p < 0.05), and sex (p < 0.05 for mast cells and male sex). Reproduced
with permission from Gibson PG, Wlodarczyk JW, Clancy RL, et al. Epidemiological association of airway inflammation with asthma symptoms and airway hyperresponsiveness in childhood. Am J Respir Crit Care Med 1998; 158:36-41
ASTHMA EXACERBATIONS
Analysis of sputum has been very useful in studying the mechanisms of asthma exacerbations. This has been done using either spontaneously expectorated sputum or sputum induced with normal saline inhalation since administration of hypertonic saline poses a risk of excessive bronchoconstriction in such cases. Sputum eosinophilia increases several-fold during exacerbations of asthma. In mild exacerbations with symptomatic deterioration, but no major decline in lung function, there is a predominant sputum eosinophilia with eosinophil degranulation and ECP release. These markers parallel the changes in asthma symptoms during an exacemrbation. Importantly, sputum markers deteriorate when symptoms exacerbate even though there is no major decline in lung function. This suggests that sputum is a sensitive marker of disease activity in childhood asthma (Figure 6.5).
