title: Mycoplasma pneumoniae-induced activation and cytokine production in rodent mast cells.
abstract: BACKGROUND
  Mycoplasma pneumoniae is a respiratory tract pathogen that has been associated with severe exacerbations in patients with chronic asthma. Murine models of infection have recently been established, with disease manifestations similar to those observed in human subjects. Previous studies have suggested that this organism is capable of producing activation of a wide range of immunologic cell types.
  
  
  OBJECTIVE
  We sought to determine whether M pneumoniae can induce mast cell activation in the rodent mast cell line RBL-2H3.
  
  
  RESULTS
  After 4 hours of coculture, morphologic changes indicative of activation were observed by means of electron microscopy, and M pneumoniae was identified, by means of immunoelectron microscopy, adhering to mast cell membranes. Coculture of rat basophilic leukemia cells with viable M pneumoniae for 4 hours resulted in net release of beta-hexosaminidase and serotonin into the supernatant. Live, but not heat-killed, organisms induced the release of IL-4 protein into the culture supernatant, with a peak at 4 hours. During coculture with M pneumoniae, production of mRNA for IL-4, IL-6, and TNF-alpha was upregulated after 2 hours and had returned to near baseline by 24 hours after infection.
  
  
  CONCLUSIONS
  We conclude that viable M pneumoniae induces activation of mast cells with release of granule contents, as well as cytokine production.
authors.affiliation: Division of Developmental and Clinical Immunology, Department of Pediatrics and Microbiology, University of Alabama, Birmingham 35294-3300, USA.
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Hoek
authors.forename: Gail H
authors.initials: GH
authors.lastname: Cassell
authors.forename: Lynn B
authors.initials: LB
authors.lastname: Duffy
authors.forename: T Prescott
authors.initials: TP
authors.lastname: Atkinson
mesh_terms: D000818:Animals; D015550:Cell Degranulation; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism; D008854:Microscopy, Electron; D009177:Mycoplasma pneumoniae / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014407:Tumor Cells, Cultured; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D001619:beta-N-Acetylhexosaminidases