Clinical and immunologic factors associated with the presence or absence of airways hyper-responsiveness in childhood asthma

Background During the baseline period of a clinical trial comparing different dosage schedules of inhaled steroids, asthmatic children (aged 6-10 years) were expected to meet the inclusion criterion of airways hyper-responsiveness (PD20 methacholine <80 mug) after withdrawal of inhaled corticosteroids for 2-8 weeks. However, many children failed to do so. Objective It has been shown that young wheezing children may outgrow their symptoms. We investigated if differences between children with and without airways hyper-responsiveness after withdrawal of inhaled corticosteroids were compatible with differences between transient and persistent wheezers found in other studies. Methods Seventy-eight children entered the study, of which 41 developed airways hyper- responsiveness after withdrawal of inhaled corticosteroids, and 37 did not. These two groups of children were compared with respect to differences in demographic, clinical, and immunological features (IL-4, IL-5, IL-10, and IFN-gamma produced by Con A stimulated peripheral mononuclear cells (PBMCs) and serum IL-4, IL-5 and soluble intercellular adhesion molecule-1 (sICAM-1)). Results Hyper-responsive children had more atopic features (positive RAST, high IgE, eczema), lower levels of FEV1 and lower concentrations of sICAM-1 than non-hyper-responsive children. Apart from a borderline significantly higher IL-4 production in the hyper-responsive group, other immunologic parameters were comparable. Multivariate logistic regression analysis showed that high serum IgE, low FEV1 , and low sICAM-1 levels were independently associated with the presence of airways hyper-responsiveness after stopping inhaled corticosteroids. Atopy was associated with higher concentrations of IL-4 in the hyper-responsive group. Conclusion After withdrawal of inhaled corticosteroids many children previously diagnosed with asthma did not develop airways hyper-responsiveness. We conclude that hyper-responsive children share features with persistent wheezers as found in previous studies, whereas the non-hyper- responsive children may represent transient wheezers