title: Effects of dexamethasone on cell-mediated immune responses in cattle sensitized to Mycobacterium bovis.
abstract: Systemic administration of dexamethasone led to a significant reduction in the size of the tuberculin reaction in response to intradermal injection of bovine purified protein derivative in 18 cattle experimentally sensitized to Mycobacterium bovis (P < 0.01) and 8 cattle naturally infected with M bovis (P < 0.001). The reaction in 6 of the 7 M bovis infected cattle that received dexamethasone was classified as negative for the standard interpretation of the single intradermal comparative tuberculin test. Significantly fewer BoCD2+ (P < 0.05) and BoCD4+ T cells (P < 0.001) were present at the reaction site and in blood of dexamethasone-treated cattle, compared with untreated control cattle. Significantly fewer cells expressing the interleukin-2 receptor and WC1+ gamma delta T cells (P < 0.001), and a significantly greater number of cells expressing the ACT2 antigen (P < 0.05) were found at the reaction site in dexamethasone treated cattle than in controls. The number of BoCD8+ T cells at the reaction site and in blood was not significantly affected by administration of dexamethasone. In vitro production of interferon-gamma by lymphocytes incubated with bovine purified protein derivative also was significantly lower (P < 0.01) in the dexamethasone treated cattle.
authors.affiliation: Faculty of Veterinary Medicine, University College Dublin, Ballsbridge, Ireland.
authors.forename: M L
authors.initials: ML
authors.lastname: Doherty
authors.forename: H F
authors.initials: HF
authors.lastname: Bassett
authors.forename: P J
authors.initials: PJ
authors.lastname: Quinn
authors.forename: W C
authors.initials: WC
authors.lastname: Davis
authors.forename: M L
authors.initials: ML
authors.lastname: Monaghan
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D018801:CD2 Antigens / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D002417:Cattle; D003907:Dexamethasone / Q000494:pharmacology*; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D007111:Immunity, Cellular / Q000187:drug effects; D007114:Immunization / Q000662:veterinary; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000096:biosynthesis; D007958:Leukocyte Count / Q000662:veterinary; D009163:Mycobacterium bovis / Q000276:immunology*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology; D015375:Receptors, Interleukin-2 / Q000276:immunology; D012867:Skin / Q000187:drug effects / Q000276:immunology; D014373:Tuberculin / Q000494:pharmacology; D014374:Tuberculin Test / Q000662:veterinary; D014380:Tuberculosis, Bovine / Q000276:immunology*
chemical_list: D000893:Anti-Inflammatory Agents; D018801:CD2 Antigens; D016692:Receptors, Antigen, T-Cell, gamma-delta; D015375:Receptors, Interleukin-2; D014373:Tuberculin; D003907:Dexamethasone; D007371:Interferon-gamma