title: Cytotoxicity and cytokine production by bovine alveolar macrophages challenged with wild type and leukotoxin-deficient Mannheimia haemolytica.
abstract: Leukotoxin (LKT) is a virulence factor for Mannheimia haemolytica. In this study, bovine alveolar macrophages (BAMs) were challenged with wild type (wt) and LKT deficient (lkt(-)) M. haemolytica at a concentration of 1 bacterium/BAM and the cytokine response was quantified by ELISA and real-time reverse transcriptase-PCR. Significant increases in protein concentrations of tumor necrosis factor (TNF)-α and interleukin (IL)-10 were observed in supernatants obtained from BAMs challenged with the lkt(-) strain of M. haemolytica compared with wt challenged BAMs. There were no significant differences in mRNA expression of TNFα, IL-1ß, IL-6, IL-8 or IL-10 between BAMs challenged with the lkt(-) strain of M. haemolytica compared with wt challenged BAMs. BAMs challenged with the wt strain exhibited, on average, 43% more cytotoxicity than lkt(-) challenged BAMs (P<0.01).
authors.affiliation: Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078, USA. ksingh08@illinois.edu
authors.forename: Kuldeep
authors.initials: K
authors.lastname: Singh
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Confer
authors.forename: Jayne C
authors.initials: JC
authors.lastname: Hope
authors.forename: Theresa
authors.initials: T
authors.lastname: Rizzi
authors.forename: John H
authors.initials: JH
authors.lastname: Wyckoff
authors.forename: Hsin-Yi
authors.initials: HY
authors.lastname: Weng
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Ritchey
mesh_terms: D000818:Animals; D002417:Cattle / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D003603:Cytotoxins / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005098:Exotoxins / Q000172:deficiency*; D007166:Immunosuppressive Agents; D016676:Macrophages, Alveolar / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D016978:Mannheimia haemolytica / Q000378:metabolism* / Q000472:pathogenicity; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D037521:Virulence Factors
chemical_list: D016207:Cytokines; D003603:Cytotoxins; D005098:Exotoxins; D007166:Immunosuppressive Agents; D037521:Virulence Factors; C018579:leukotoxin