title: The effect of Pasteurella haemolytica A1 leukotoxic culture supernate on the in vitro proliferative response of bovine lymphocytes.
abstract: The effect of sublethal concentrations of the Pasteurella haemolytica leukotoxic culture supernate on bovine lymphocyte blastogenesis was investigated. Blastogenesis in cultures stimulated with either concanavalin A (Con A) or pokeweed mitogen (PWM) was inhibited in the presence of the supernate, as was the response to purified protein derivative in lymphocytes from BCG-vaccinated cattle. Partially purified leukotoxin had a similar effect. Pre-incubation of the leukotoxic supernate with a polyclonal rabbit antiserum raised to the immunogenic molecule of recombinant leukotoxin (r LktA) abrogated this effect, implicating leukotoxin as the factor responsible for the inhibition. B cell enriched cultures tended to be more sensitive to leukotoxic effects than did T cell enriched cultures. Although only ruminant cells are susceptible to the lethal effects of P. haemolytica leukotoxin, the toxin did inhibit both Con A- and PWM-induced proliferation of human and dog lymphocytes. As well, at high leukotoxin doses, Con A-stimulated pig lymphocyte proliferation was reduced. Rabbit lymphocytes were not affected by leukotoxin in either Con A- or PWM-stimulated cultures.
authors.affiliation: Department of Veterinary Microbiology and Immunology, University of Guelph, Canada.
authors.forename: A L
authors.initials: AL
authors.lastname: Majury
authors.forename: P E
authors.initials: PE
authors.lastname: Shewen
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D001427:Bacterial Toxins / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D002417:Cattle; D003470:Culture Media; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D004285:Dogs; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D016978:Mannheimia haemolytica / Q000276:immunology*; D011817:Rabbits; D011994:Recombinant Proteins / Q000276:immunology; D013552:Swine; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D001427:Bacterial Toxins; D003470:Culture Media; D011994:Recombinant Proteins