title: Recombinant interleukin-6 increases the intracellular and extracellular growth of Mycobacterium avium.
abstract: Human monocytes were isolated from the peripheral blood of normal donors and allowed to differentiate in vitro into macrophages. The susceptibility of these cells to infection with a virulent Mycobacterium avium and its modulation by some soluble factors was monitored. The virulent strain of Mycobacterium avium grew progressively in untreated macrophage monolayers. Interleukin-6 (IL-6) was tested for its ability to modulate the macrophage-mycobacteria interaction. Surprisingly, IL-6 was shown to increase M. avium growth in macrophage monolayers by twofold as compared with untreated cells, when added before or after infection. Moreover, addition of rIL-6 to replicating mycobacteria in vitro enhanced their growth two- to three-fold as compared with cultures treated with rIL-6 and a rabbit antiserum to rIL-6. Treatment with IL-6 and interferon-gamma (IFN-gamma) or IL-4 did not modify the growth promoting effect of IL-6 in human macrophages. Overall, our results suggest that IL-6 may contribute significantly to the pathogenesis of infections with M. avium by promoting mycobacterial growth.
authors.affiliation: ICI Pharmaceuticals, Macclesfield, Cheshire, England.
authors.forename: M
authors.initials: M
authors.lastname: Denis
authors.forename: E O
authors.initials: EO
authors.lastname: Gregg
mesh_terms: D006801:Humans; D015850:Interleukin-6 / Q000494:pharmacology*; D007700:Kinetics; D008264:Macrophages / Q000382:microbiology*; D009162:Mycobacterium avium / Q000254:growth & development*; D011994:Recombinant Proteins / Q000494:pharmacology
chemical_list: D015850:Interleukin-6; D011994:Recombinant Proteins