title: The interaction of Naegleria fowleri amoebae with murine macrophage cell lines.
abstract: The present study was undertaken to determine whether murine macrophage cell lines exhibited in vitro amoebicidal activity comparable to that elicited by activated murine peritoneal macrophages. Peritoneal macrophages activated in vivo by bacillus Calmette-Guérin or Propionibacterium acnes demonstrated significant cytolysis of Naegleria fowleri amoebae. The macrophage cell line RAW264.7 also effected cytolysis of amoebae, but to a lesser extent than that elicited by activated peritoneal macrophages. However, the macrophage cell lines, J774A.1 and P388D1, did not exhibit amoebicidal activity. Macrophage conditioned medium prepared from RAW264.7 macrophages mediated cytolysis of L929 tumor cells but had no effect on N. fowleri amoebae. In addition, neither recombinant tumor necrosis factor nor recombinant interleukin-1 exhibited amoebicidal activity. Scanning electron microscopy of co-cultures revealed that N. fowleri bound to activated peritoneal macrophages and RAW264.7 macrophages. These results suggest that RAW264.7 macrophages treated in vitro with lipopolysaccharide are similar to macrophages activated in vivo in that they effect contact-dependent cytolysis of Naegleria fowleri amoebae. The RAW264.7 macrophages are unlike primary macrophage cultures in that they either do not release soluble amoebicidal factors into the conditioned medium or they release insufficient quantities.
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University, Medical College of Virginia, Richmond 23298-0678.
authors.forename: K
authors.initials: K
authors.lastname: Fischer-Stenger
authors.forename: G A
authors.initials: GA
authors.lastname: Cabral
authors.forename: F
authors.initials: F
authors.lastname: Marciano-Cabral
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis; D001685:Biological Factors / Q000276:immunology; D002460:Cell Line; D003602:Cytotoxicity, Immunologic; D008264:Macrophages / Q000276:immunology* / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D008855:Microscopy, Electron, Scanning; D009253:Naegleria / Q000276:immunology* / Q000648:ultrastructure; D009369:Neoplasms / Q000276:immunology; D010529:Peritoneal Cavity / Q000166:cytology; D014407:Tumor Cells, Cultured
chemical_list: D000913:Antibodies, Protozoan; D001685:Biological Factors