Exhaled nitric oxide, serum ECP and airway responsiveness in mild asthmatic children

The purpose of the present study was to assess the possible relationships b etween exhaled nitric oxide (ENO), a circulating marker of eosinophil activ ation, serum eosinophil cationic protein (SECP), level of airway responsive ness to methacholine and lung function in asthmatic children, as well as to compare these markers between children with and without inhaled steroid th erapy. In a cross-sectional study ENO, SECP and bronchial hyperresponsiveness to m ethacholine were evaluated in a group of 57 asthmatic children (21 without and 36 with regulator inhaled steroid therapy; aged 6-13 yrs), ENO was significantly lower in steroid treated children (p<0.01), No signif icant differences between steroid treated and untreated children were obser ved for the provocative concentration of methacholine causing a 20% faill i n forced expiratory volume in one second (FEV1; PC20), SECP and FEV1. In th e whole study population significant increase correlations were observed be tween PC20 and SECP (r=-0.329, p=0.013) and between ENO and FEV1% of predic ted (r=-0.348, p<0.01). In the group not receiving inhaled steroids the inv erse relationship between PC20 and SECP was more evident (r=-0.581, p<0.001 ). In the steroid-treated group a significant inverse relationship was obse rved between ENO and FEV1 (r=-0.426, p=0.0011). The level of exhaled nitric oxide and the relationships between lung functi on, bronchial reactivity and markers of inflammation are different between steroid-treated and untreated asthmatic children. This has implications for the monitoring of asthma in childhood.