Atopic and Nonatopic Asthma in Children: two Different Diseases?

The majority of the studies in the field of childhood asthma lie within the scope of allergy/atopic asthma; however, airway hyperresponsiveness is considered a marker of asthma, independent of the atopic status and should be regarded as a parallel pathological process that can lead to subsequent symptoms and clinical evidence of asthma in children, without the evidence of atopy. The aim of this study is to estimate the possible differences in clinical and lung functions, and the immunological status of children with atopic and nonatopic asthma phenotypes. In a prospective study design, 54 children (age 3-18 years) in Germany were monitored via active surveillance, by twice-a-week phone calls. All the children were divided into two groups, based on their atopic status, clinical date and lung function tests. The first 27 patients had atopic asthma (AA), whereas the second set of 27 patients had nonatopic asthma (NA). All patients underwent IgE and RAST tests for the most common inhalant allergens, and a quantitative measurement of Eosinophil Cationic Protein (ECP) by CAP-radioallergosorbent test-fluorescence enzyme immunoassay (UniCAP, Pharmacia Diagnostics, Germany). Further, the IgA, IgM, IgG subclasses, IL-6 and CRP levels in the serum were tested. The resultant data showed significant differences in the prevailing IgE level 317.5±58 g/l in AA versus 83±21 in NA. However, there was no significant distinction either in the ECP serum level in children with atopic and nonatopic asthma or in the IL-6 serum level. An unexpected result was the significant drop in the level of serum CRP in group NA – 0.68±0.37 g/l; while in group AA this result was 1.5±0.38 g/l. No significant differences were noted between the mean values of the IgM and IgG levels in patients of all groups; however, the IgG levels increased only in the children with nonatopic asthma. Our study did not reveal any type of immunoglobulin deficiency. The IgA level was relatively decreased in children with nonatopic asthma compared with those with the atopic form. Patients from group NA had significantly higher IgG4 subclass levels than patients from group AA. The results of our study show that both atopic and nonatopic asthma are diseases, with similar inflammatory changes, however having probably different pathogenetic immunological mechanisms.