title: Absence of circulating products of oxygen derived free radicals in acute severe asthma.
abstract: Oxygen derived free radicals (ODFRs), generated by eosinophils, neutrophils, alveolar macrophages and mast cells, have been proposed as important mediators of inflammatory damage in asthma. We attempted to assess the role of these free radicals in patients with acute asthma by determining serum concentrations of phospholipid-esterified 9, 11 and the parent 9, 12-linoleic acid isomers (9, 11-LA, 9, 12-LA), using HPLC and diode array detection. The diene conjugate, 9, 11-LA, has been shown to be a sensitive and specific marker of free radical activity in other inflammatory conditions. Eight patients (6 female, aged 19-42 years) with acute asthma (mean peak expiratory flow 92 +/- (26) m (SEM) l.min-1, mean PaO2 8.4 (1.0) kPa were studied at 0, 6, 12, 24 and 48 hours after admission to hospital and again 4-6 weeks later. Initial blood samples were taken prior to the administration of oxygen or drug therapy. On admission, mean concentrations of 9, 11-LA and 9, 12-LA were normal at 18.0 (2.8) and 1024 (118) mumol.l-1. All subsequent 9, 11-LA serum concentrations were likewise in the normal range. The serum 9, 11-LA/9, 12-LA ratio was 1.9 (0.4) on admission and 1.6 (0.2) in convalescence (Normal Range 1.0-3.8). These findings in peripheral blood do not support a major role or oxygen derived free radical production in acute asthma, but local airway production cannot be excluded.
authors.affiliation: Department of Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London.
authors.forename: E R
authors.initials: ER
authors.lastname: Chilvers
authors.forename: H
authors.initials: H
authors.lastname: Garratt
authors.forename: M K
authors.initials: MK
authors.lastname: Whyte
authors.forename: R
authors.initials: R
authors.lastname: Fink
authors.forename: P W
authors.initials: PW
authors.lastname: Ind
mesh_terms: D000328:Adult; D001249:Asthma / Q000097:blood* / Q000209:etiology; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005609:Free Radicals; D006801:Humans; D007536:Isomerism; D008041:Linoleic Acids / Q000097:blood*; D044243:Linoleic Acids, Conjugated; D008297:Male; D010100:Oxygen / Q000378:metabolism
chemical_list: D005609:Free Radicals; D008041:Linoleic Acids; D044243:Linoleic Acids, Conjugated; C046938:9,11-linoleic acid; D010100:Oxygen