House dust mite-specific immunoglobulin E and longitudinal exhaled nitric oxide measurements in children with atopic asthma

PURPOSE House dust mite (HDM) has been suggested to be the most important aeroallergen responsible for atopic asthma in Korea. We aimed to investigate that specific IgE antibodies to HDM and other common indoor aeroallergens contribute differently to total serum IgE and show different relationships with longitudinal fractional exhaled nitric oxide (FeNO) measurements in Korean atopic asthmatic patients. METHODS A total of 193 children aged 8 to 16 years with intermittent or mild persistent atopic asthma were recruited. Sera were assayed for total IgE and specific IgE antibodies to HDM and other common indoor allergens. FeNO was serially measured 10 times or more over 2 years when subjects were not receiving controller medications. RESULTS In 152 children who completed the study, IgE antibodies to specific HDM were more prevalent than those to other common indoor aeroallergens. In addition, IgE antibody titers to HDM were the strongest contributor to total IgE increases. Furthermore, only HDM-specific IgE antibody titer significantly correlated with maximum FeNO (r=0.21, P=0.029) and the rate of FeNO higher than 21 parts per billion (ppb) (r=0.30, P=0.002). Eight patients (5%) were found to have maximum FeNO of 21 ppb or less, suggesting the presence of a low FeNO phenotype among atopic asthmatic patients. CONCLUSION The quantity of HDM-specific IgE antibody provides a possible explanation for increases of total IgE and significantly correlates with the amount and frequency of FeNO increases in Korean atopic asthmatic patients.