title: Intracellular trafficking in Mycobacterium tuberculosis and Mycobacterium avium-infected macrophages.
abstract: Despite the potential role of the macrophage in the eradication of invading microbes, Mycobacterium species have evolved mechanisms to ensure their survival and replication inside the macrophage. Particles phagocytosed by macrophages normally will be delivered into acid lysosomal compartments for degradation. Mycobacterium must, in some way, avoid this fate by modulation of their phagosome. Immunoelectron microscopy of macrophages infected with Mycobacterium avium or Mycobacterium tuberculosis indicates that the vacuolar membrane surrounding the bacilli possesses the late endosomal/lysosomal marker, LAMP-1 (lysosomal-associated membrane protein-1), but lacks the vesicular proton-ATPase. Analysis of the intersection of the bacteria-containing vacuoles with the endocytic network of the macrophage supports previous studies indicating that these bacilli restrict the fusion capability of their intracellular compartments. The occurrence of vesicles containing lipoarabinomannan, discrete from those containing Mycobacterium, indicate that material does traffic out from the mycobacterial vacuole. To compensate for this loss of membrane, the vacuole must remain dynamic and fuse with LAMP-1-containing vesicles to maintain the density of this marker.
authors.affiliation: Department of Molecular Microbiology, Washington University Medical School, St. Louis, MO 63110.
authors.forename: S
authors.initials: S
authors.lastname: Xu
authors.forename: A
authors.initials: A
authors.lastname: Cooper
authors.forename: S
authors.initials: S
authors.lastname: Sturgill-Koszycki
authors.forename: T
authors.initials: T
authors.lastname: van Heyningen
authors.forename: D
authors.initials: D
authors.lastname: Chatterjee
authors.forename: I
authors.initials: I
authors.lastname: Orme
authors.forename: P
authors.initials: P
authors.lastname: Allen
authors.forename: D G
authors.initials: DG
authors.lastname: Russell
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000502:physiology; D001854:Bone Marrow Cells; D004705:Endocytosis / Q000502:physiology; D008070:Lipopolysaccharides / Q000276:immunology; D008264:Macrophages / Q000382:microbiology* / Q000648:ultrastructure*; D051379:Mice; D008807:Mice, Inbred BALB C; D016253:Microscopy, Immunoelectron; D009162:Mycobacterium avium / Q000276:immunology*; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D014617:Vacuoles / Q000382:microbiology
chemical_list: D008070:Lipopolysaccharides; C050016:lipoarabinomannan