title: Effect of Pseudomonas aeruginosa exotoxin A on IFN-gamma synthesis: expression of costimulatory molecules on monocytes and activity of NK cells.
abstract: The aim of the study was (1) to evaluate the effect of Pseudomonas aeruginosa Exotoxin A (P-ExA) on the production of IFN-gamma in anti-CD3 induced human peripheral blood mononuclear cells (PBMC) and (2) to establish the effect of P-ExA on the IFN-gamma dependent cellular activities such as the expression of costimulatory molecules on monocytes and cytotoxicity of NK cells. The toxin in a high dose (100 ng/ml) inhibited IFN-gamma synthesis. Inhibitory effect of P-ExA was abolished by IL-1alpha which in a combination with P-ExA exerted a strong synergistic effect on IFN-gamma synthesis. Other monokines such as IL-1beta, IL-6, TNF-alpha neither reversed the inhibitory effect of P-ExA nor induced production of IFN-gamma. P-ExA also inhibited IFN-gamma-induced cellular events: (1) expression of costimulatory molecules on monocytes (CD80, CD86, ICAM-1, HLA-DR); (2) cytotoxic activity of NK cells. Inhibition of NK cells activity by P-ExA was not reversed by cytokines such as IL-2, IFN-alpha and TNF-alpha, which are known to enhance effector functions of NK cells. From these results we conclude that: (1) inhibition of IFN-gamma synthesis, as well as IFN-gamma-induced expression of costimulatory molecules and NK-cell effector functions may lead to suppression of specific and non-specific defense mechanisms, respectively, which are necessary for elimination of PA bacteria; (2) enhancement of IFN-gamma synthesis induced by P-ExA in a combination with IL-1alpha may cause harmful, Th1 cells dependent, inflammatory reactions of the host (septic shock, tissue damage) during infection with Pseudomonas aeruginosa.
authors.affiliation: Department of Ihnmunology, Child Health Center, Warsaw, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Michałkiewicz
authors.forename: J
authors.initials: J
authors.lastname: Stachowski
authors.forename: C
authors.initials: C
authors.lastname: Barth
authors.forename: J
authors.initials: J
authors.lastname: Patzer
authors.forename: D
authors.initials: D
authors.lastname: Dzierzanowska
authors.forename: K
authors.initials: K
authors.lastname: Madaliński
mesh_terms: D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D002478:Cells, Cultured; D005098:Exotoxins / Q000276:immunology*; D006801:Humans; D016898:Interferon-alpha / Q000096:biosynthesis; D007371:Interferon-gamma / Q000096:biosynthesis*; D007376:Interleukin-2 / Q000096:biosynthesis; D007694:Killer Cells, Natural / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D009000:Monocytes / Q000276:immunology*; D011550:Pseudomonas aeruginosa / Q000276:immunology*; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
chemical_list: D036002:ADP Ribose Transferases; D001427:Bacterial Toxins; D005098:Exotoxins; D016898:Interferon-alpha; D007371:Interferon-gamma; D007376:Interleukin-2; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A