ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the relationship between leukotriene expression in blood polymorphonuclear leukocytes (PMNL) and the efficacy of inhaled corticosteroids (ICS) in children with asthma.</p><p><b>METHODS</b>Thirty-two children with asthma (5-12 years) and ten healthy children (control group) were enrolled. The asthmatic children were subdivided into ICS well-controlled and ICS poorly-controlled groups based on their clinical symptoms and lung function. The level of leukotriene C4 synthase (LTC4S) mRNA in PMNL was detected by fluorescence quantitative polymerase chain reaction. The level of LTC4S mRNA was expressed by the value of qCt, and the value of qCt was diversely correlated with the level of LTC4S mRNA expression. The concentration of urinary leukotriene E4 (LTE4) was measured using ELISA.</p><p><b>RESULTS</b>The expression of LTC4S mRNA in PMNL was significantly higher in children with asthma (qCt: 1.12+/-0.27) than that in the control group (qCt: 1.42+/-0.12; P< 0.05). The expression of LTC4S mRNA in PMNL in the ICS poorly-controlled group (qCt: 1.03+/-0.17) was significantly higher than that in the ICS well-controlled group (qCt: 1.24+/-0.33; P< 0.05) and the control group(1.42+/-0.12; P< 0.01). There was no significant difference in the level of urinary LTE4 among the the ICS poorly-controlled, the ICS well-controlled and the control groups.</p><p><b>CONCLUSIONS</b>LTC4S mRNA expression in PMNL in asthmatic children increases, and the LTC4S mRNA expression in the ICS poorly-controlled group is higher than that in the ICS well-controlled group. This suggests that an increased leukotriene expression might be associated with poorly-controlled asthma.</p>