title: Inhibition of Chlamydia pneumoniae growth in HEp-2 cells pretreated with gamma interferon and tumor necrosis factor alpha.
abstract: An in vitro culture system was used to study the effects of increasing concentrations of human cytokines on the intracellular replication of Chlamydia pneumoniae. HEp-2 cell monolayers, pretreated for 24 h with 200 U of human recombinant gamma interferon (IFN-gamma) per ml restricted the intracellular replication of C. pneumoniae. Tumor necrosis factor alpha (TNF-alpha; 25 ng/ml) exhibited a synergistic effect with IFN-gamma by reducing the concentration of IFN-gamma necessary to restrict intracellular growth to 100 U/ml. The addition of 200 micrograms of tryptophan per ml significantly reversed the inhibitory effects of IFN-gamma and TNF-alpha, suggesting involvement of the indoleamine-2,3-dioxygenase pathway in the restriction process.
authors.affiliation: Division of Infectious Diseases, University of Louisville School of Medicine, Kentucky, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Summersgill
authors.forename: N N
authors.initials: NN
authors.lastname: Sahney
authors.forename: C A
authors.initials: CA
authors.lastname: Gaydos
authors.forename: T C
authors.initials: TC
authors.lastname: Quinn
authors.forename: J A
authors.initials: JA
authors.lastname: Ramirez
mesh_terms: D016993:Chlamydophila pneumoniae / Q000254:growth & development*; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma