Two distinct, stable inflammatory phenotypes have been described in adults with asthma: eosinophilic and non-eosinophilic. This study evaluated sputum cytology in 51 children with severe asthma and 28 with mild to moderate asthma who were followed over 3–6 months.
78% of the children had increased levels of inflammatory cells in at least one sputum sample. In the longitudinal analysis, 63% of children demonstrated two or more phenotypes.
Change in phenotype was not related to change in inhaled corticosteroid (ICS) dose or asthma control, nor was it reflected in a change in exhaled nitric oxide (FENO).
Remarkably, 41% of children fulfilled the criteria for non-eosinophilic asthma on one occasion and eosinophilic on another. There were no differences in severity, asthma control, atopy, ICS dose or FEV1 between those who were always non-eosinophilic and those always eosinophilic.
Eosinophil. Image source: Wikipedia.
The authors concluded that sputum inflammatory phenotypes are not stable in children with asthma.
This study was included in the monthly review of the top asthma articles at the website of the World Allergy Organization (WAO) (I am the web editor of the project).
Sputum inflammatory phenotypes are not stable in children with asthma. Louise Fleming et al. Thorax 2012;67:675-681 doi:10.1136/thoraxjnl-2011-201064