Morphological changes in eosinophils are reliable markers of the severity of an acute asthma exacerbation in children.

BACKGROUND Early identification of the severity of asthma exacerbation would be helpful for the management of patients. We aimed to evaluate the correlation of morphological change in activated eosinophils and the severity of an asthma exacerbation. METHODS Blood was collected from 55 asthmatic children: 40 of whom were having an exacerbation, 15 symptom-free, and 15 healthy controls. The percentage of eosinophils with morphological changes (emission of single or multiple pseudopods, presence of cytoplasmic vacuoles, releasing a small, moderate, or large quantity of granules, spreading, eosinophil death, and presence of cluster of free eosinophil granules) was quantified after the adherence to a slide and compared using the Mann-Whitney test. The correlation between the severity of the asthma exacerbation and the percentage changed eosinophils was tested with Spearman's correlation. RESULTS The proportion of activated eosinophils was higher in asthmatic symptom-free children than in the control group, and acute asthma exacerbation produced an additional increase in eosinophil activation (P < 0.01). More significantly increased morphological changes were emissions of multiple pseudopods, presence of cytoplasmic vacuoles, spreading, and presence of a cluster of free eosinophil granules (P < 0.001). The following were correlated with the severity of an asthma exacerbation: ≥14% of eosinophils emitting single pseudopod, 8% emitting multiple pseudopods, 17% with vacuoles, 28% eosinophils releasing a large quantity of granules, and 66% of spread eosinophils. CONCLUSIONS Quantifying the morphological changes in eosinophils is a feasible, easy, and reliable manner to identify the severity of an asthma exacerbation and therefore might improve the clinical management of asthmatic children.