title: CR3-dependent resistance to acute Toxoplasma gondii infection in mice.
abstract: Studies were performed to determine whether resistance to acute Toxoplasma gondii infection in mice depends on a mechanism involving CR3, the type 3 complement receptor. Nineteen of 22 mice (86%) given multiple injections of the anti-CR3 monoclonal antibody, 5C6, prior to and after intraperitoneal inoculation of cysts of the ordinarily mildly virulent ME49 strain of T. gondii died within 8 to 12 days, whereas control antibody-treated mice survived. All (five of five) anti-CR3-treated BALB/c mice infected via the natural peroral route died within 8 days of infection. Flow cytometric analysis of cells recovered from peritoneal lavages of anti-CR3-treated T. gondii-infected mice revealed that the percentage of Thy-1+ CD4- CD8- cells was reduced to about 50% of that of control antibody-treated mice and to about 20% of the number of such cells in controls. The numbers of macrophages, polymorphonuclear leukocytes, and lymphocytes recovered from the peritoneal cavities of T. gondii-infected mice were all reduced in anti-CR3-treated mice to about 40% of those of controls. In addition, anti-CR3-treated mice had less than 25% of the induced NK cell activity of the controls, and gamma interferon was reduced to undetectable levels. Thus, the rapid death of anti-CR3-treated mice was probably caused by impaired preimmune defenses. Histological examination of anti-CR3-treated T. gondii-infected mice revealed extensive liver pathology compared with that of infected mice given a control antibody or uninfected mice given anti-CR3. The inflammation, degeneration, and necrosis in most of the anti-CR3-treated mice were severe enough to account for the observed mortalities.
authors.affiliation: Trudeau Institute, Inc., Saranac Lake, New York 12983, USA.
authors.forename: L L
authors.initials: LL
authors.lastname: Johnson
authors.forename: G W
authors.initials: GW
authors.lastname: Gibson
authors.forename: P C
authors.initials: PC
authors.lastname: Sayles
mesh_terms: D000208:Acute Disease; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D005260:Female; D007371:Interferon-gamma / Q000032:analysis; D007694:Killer Cells, Natural / Q000276:immunology; D016177:Macrophage-1 Antigen / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D014124:Toxoplasmosis, Animal / Q000276:immunology* / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D016177:Macrophage-1 Antigen; D007371:Interferon-gamma