title: Type 1 and type 2 cytokine imbalance in acute respiratory syncytial virus bronchiolitis.
abstract: We examined the in vivo immune response of infants to natural respiratory syncytial virus (RSV) infection through analysis of cytokine levels in nasal lavage fluid and stimulated peripheral blood mononuclear cells. Eighty-eight babies with at least one parent with atopy and asthma were prospectively studied through their first winter. Twenty-eight infants had an upper respiratory tract infection where RSV was detected, of whom nine developed signs of acute bronchiolitis. Nasal lavage specimens were assayed for interferon-gamma, interleukin (IL)-4, IL-10, and IL-12 and the RSV load determined by quantitative polymerase chain reaction. Messenger RNA (mRNA) was extracted from stimulated peripheral blood mononuclear cells and interferon-gamma, IL-4, IL-12, and IL-18 mRNA levels determined by polymerase chain reaction. Cytokine profiles were analyzed in relation to clinical outcome. The IL-4/interferon-gamma ratio for infants with acute bronchiolitis was elevated in nasal lavage fluid on both Days 1-2 (p = 0.014) and Days 5-7 (p = 0.001) of the illness compared with infants with upper respiratory tract infection alone. Those with acute bronchiolitis demonstrated a higher IL-10/IL-12 ratio (p = 0.0015) on Days 1-2. IL-18 mRNA levels were reduced (p = 0.019) and the IL-4/interferon-gamma ratio elevated (p = 0.01) in stimulated peripheral blood mononuclear cells from infants with acute bronchiolitis. There was no difference in initial RSV load. These data strongly implicate excess type 2 and/or deficient type 1 immune responses in the pathogenesis of RSV bronchiolitis.
authors.affiliation: Department of Child Health, Infection, Inflammation and Repair Division, University of Southampton, Southampton SO16 6YD, UK. julianlegg@yahoo.co.uk
authors.forename: Julian P
authors.initials: JP
authors.lastname: Legg
authors.forename: Imran R
authors.initials: IR
authors.lastname: Hussain
authors.forename: Jill A
authors.initials: JA
authors.lastname: Warner
authors.forename: Sebastian L
authors.initials: SL
authors.lastname: Johnston
authors.forename: John O
authors.initials: JO
authors.lastname: Warner
mesh_terms: D000208:Acute Disease; D001990:Bronchiolitis, Viral / Q000175:diagnosis / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D017817:Nasal Lavage Fluid / Q000276:immunology; D016133:Polymerase Chain Reaction; D011336:Probability; D011379:Prognosis; D011446:Prospective Studies; D012367:RNA, Viral / Q000032:analysis; D018357:Respiratory Syncytial Virus Infections / Q000175:diagnosis / Q000276:immunology*; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D018417:Th1 Cells / Q000276:immunology*; D018418:Th2 Cells / Q000276:immunology*
chemical_list: D016207:Cytokines; D012367:RNA, Viral