title: Increased macrophage-derived chemokine in exhaled breath condensate and plasma from children with asthma.
abstract: BACKGROUND
  Type 2 helper T lymphocyte-specific chemokines including macrophage-derived chemokine (MDC), thymus and activation-regulated chemokine (TARC) and eotaxin are important mediators for allergic airway inflammation.
  
  
  OBJECTIVE
  We investigated whether these chemokines can be detected in exhaled breath condensate (EBC) and their relation to childhood asthma.
  
  
  METHODS
  Asthmatics recruited from paediatric clinics of a university teaching hospital were classified into intermittent asthma (IA) and persistent asthma (PA) according to Global Initiative for Asthma guidelines. EBC was collected by a disposable collection kit, whereas fractional exhaled nitric oxide (FENO) was measured by a chemiluminescence analyser. Concentrations of MDC, TARC and eotaxin in both EBC and plasma were measured using sandwich enzyme immunoassay. The intra-subject reproducibility of exhaled chemokine measurements was determined by co-efficients of variation (CV).
  
  
  RESULTS
  Forty-eight patients with PA, 36 children with IA and 18 controls were recruited. MDC and eotaxin were present in EBC from nearly all subjects, whereas TARC could be measured in EBC from 33 (32%) subjects only. The median MDC concentration in EBC was higher in PA (117 pg/mL) as compared with IA (106 pg/mL) and controls (105 pg/mL; P=0.003 for both). The median plasma MDC concentration in PA (648 pg/mL) was also higher than that in IA (520 pg/mL; P=0.002) and controls (490 pg/mL; P=0.008). The median plasma TARC concentration was also increased in PA as compared with IA (72 pg/mL vs. 35 pg/mL; P=0.004). MDC concentrations in EBC were lower in patients with PA who received high-dose inhaled corticosteroid (P=0.005). FENO was significantly higher in asthmatics than controls (P<0.0001), but it was not associated with chemokines in EBC or plasma. The mean (range) CV for measuring MDC, TARC and eotaxin in EBC (n=6) were 5.5 (2.0-7.2%), 8.8 (3.6-14.4%) and 5.2 (2.8-7.9%), respectively.
  
  
  CONCLUSIONS
  Our results suggest that MDC in EBC and MDC and TARC in plasma are increased in children with PA as compared with IA or control. MDC concentrations in EBC are suppressed in patients on high-dose inhaled corticosteroid treatment.
authors.affiliation: Departments of Paediatrics, The Chinese University of Hong Kong, Hong Kong SAR, China. leung2142@cuhk.edu.hk
authors.forename: T F
authors.initials: TF
authors.lastname: Leung
authors.forename: G W K
authors.initials: GW
authors.lastname: Wong
authors.forename: F W S
authors.initials: FW
authors.lastname: Ko
authors.forename: C W K
authors.initials: CW
authors.lastname: Lam
authors.forename: T F
authors.initials: TF
authors.lastname: Fok
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001249:Asthma / Q000188:drug therapy / Q000276:immunology*; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D001944:Breath Tests; D016022:Case-Control Studies; D054413:Chemokine CCL11; D054414:Chemokine CCL17; D054422:Chemokine CCL22; D018925:Chemokines / Q000032:analysis* / Q000097:blood; D019742:Chemokines, CC / Q000032:analysis / Q000097:blood; D002648:Child; D002908:Chronic Disease; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D008264:Macrophages / Q000276:immunology*; D008297:Male; D018709:Statistics, Nonparametric; D018418:Th2 Cells / Q000276:immunology
chemical_list: D015415:Biomarkers; C515456:CCL11 protein, human; C106230:CCL17 protein, human; C515482:CCL22 protein, human; D054413:Chemokine CCL11; D054414:Chemokine CCL17; D054422:Chemokine CCL22; D018925:Chemokines; D019742:Chemokines, CC; D005938:Glucocorticoids