The purpose of the present study was to assess the possible relationships between exhaled
nitric oxide (ENO), a circulating marker of eosinophil activation,
serum eosinophil cationic protein (SECP), level of airway responsiveness to
methacholine and lung function in asthmatic children, as well as to compare these markers between children with and without inhaled
steroid therapy. In a cross-sectional study ENO, SECP and bronchial hyperresponsiveness to
methacholine 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 significant differences between
steroid treated and untreated children were observed for the provocative concentration of
methacholine causing a 20% fall in forced expiratory volume in one second (FEV1; PC20), SECP and FEV1. In the whole study population significant increase correlations were observed between PC20 and SECP (r=-0.329, p=0.013) and between ENO and FEV1% of predicted (r=-0.348, p<0.01). In the group not receiving inhaled
steroids the inverse relationship between PC20 and SECP was more evident (r=-0.581, p<0.001). In the
steroid-treated group a significant inverse relationship was observed between ENO and FEV1 (r=-0.426, p=0.0011). The level of exhaled
nitric oxide and the relationships between lung function, 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.