title: Airway hyperresponsiveness, elevation of serum-specific IgE and activation of T cells following allergen exposure in sensitized Brown-Norway rats.
abstract: T lymphocytes may play a regulatory role in the development of allergic airway hyperresponsiveness (AHR). We have studied the relationship between airway responsiveness and a number of immunological changes in Brown-Norway rats sensitized intraperitoneally and repeatedly exposed to ovalbumin (OVA) aerosol. Acetylcholine provocation concentration (PC)150 (the concentration of acetylcholine causing a 150% increase of base-line lung resistance) was measured and peripheral blood and bronchoalveolar lavage (BAL) cells were collected 18-24hr after the final exposure. Total and OVA-specific IgE in serum was measured by enzyme-linked immunosorbent assay (ELISA). Mononuclear cells were analysed by flow cytometry after labelling with monoclonal antibodies against CD2 (pan T-cell marker), CD4, CD8 (T-cell subsets) or CD25 (interleukin-2 receptor). There were significant differences in PC150 (P < 0.05) and in OVA-specific IgE levels in serum (P < 0.002); CD4+ T cells expressed a significantly increased level of CD25 immunoreactivity in BAL, but not in peripheral blood, of rats sensitized and exposed to OVA, compared with saline-exposed controls (P < 0.02). There was a significant correlation between CD25 expression and BAL eosinophil numbers (r = 0.74, P < 0.001), PC150 (r = 0.63, P < 0.003) and OVA-specific IgE (r = 0.77, P < 0.001). These data suggest that activated T cells may be involved in the regulation of allergen-induced AHR in a relevant animal model of allergic asthma.
authors.affiliation: Department of Allergy and Clinical Immunology, National Heart and Lung Institute, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Haczku
authors.forename: K F
authors.initials: KF
authors.lastname: Chung
authors.forename: J
authors.initials: J
authors.lastname: Sun
authors.forename: P J
authors.initials: PJ
authors.lastname: Barnes
authors.forename: A B
authors.initials: AB
authors.lastname: Kay
authors.forename: R
authors.initials: R
authors.lastname: Moqbel
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D016535:Bronchial Hyperreactivity / Q000276:immunology*; D001985:Bronchial Provocation Tests; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D005260:Female; D007073:Immunoglobulin E / Q000097:blood*; D008213:Lymphocyte Activation / Q000276:immunology*; D010047:Ovalbumin / Q000276:immunology; D051381:Rats; D011914:Rats, Inbred BN; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D000485:Allergens; D007073:Immunoglobulin E; D010047:Ovalbumin