title: Opsonin-independent adherence and intracellular development of Legionella pneumophila within U-937 cells.
abstract: Legionella pneumophila adhered to and multiplied intracellularly in the human histiocytic lymphoma U-937 cell line. The infectious process was evaluated by viable bacterial cell colony counts and documented by transmission and scanning electron microscopy. In the absence of opsonins, wash-resistant bacterial adherence to host cells occurred within 1 h and attachment of 1 or 2 organisms per U-937 host cell involved close surface interactions at the prokaryotic and eukaryotic membranes. Intracellular multiplication of bacteria was maximal by 24 h after inoculation of cell monolayers. Release of L. pneumophila from these cells appeared as a lytic process that resulted in an increase in the numbers of microorganisms in the extracellular fluids and a concomitant decline in the number of intracellular bacteria. The course of cellular infection was completed by 72 h. The cellular and ultrastructural events of L. pneumophila adherence and uptake by U-937 cells in the absence of antibody or complement have been defined. In addition, this work further establishes the U-937 cell as a suitable model for investigating Legionella--host cell interactions.
authors.affiliation: Department of Microbiology, Spaulding Life Science Center, University of New Hampshire, Durham 03824-3544.
authors.forename: F G
authors.initials: FG
authors.lastname: Rodgers
authors.forename: F C
authors.initials: FC
authors.lastname: Gibson
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology*; D015169:Colony Count, Microbial; D006801:Humans; D016952:Legionella pneumophila / Q000254:growth & development* / Q000648:ultrastructure*; D016403:Lymphoma, Large B-Cell, Diffuse / Q000648:ultrastructure*; D009895:Opsonin Proteins / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D009895:Opsonin Proteins