title: Immunopathologic effects associated with Sarcocystis neurona-infected interferon-gamma knockout mice.
abstract: Interferon-gamma knockout (IFN-gamma KO) mice were infected with Sarcocystis neurona merozoites to characterize the immunopathology associated with infection. By day 14 postinfection (PI), mice developed splenomegaly and lymphadenopathy, characterized by marked lymphoid hyperplasia with increased numbers of germinal centers. Additional histopathologic changes included increased extramedullary hematopoiesis, multifocal mixed inflammatory infiltrates in the liver, perivascular infiltrate of the liver and lung, and interstitial pneumonia. The total number of B-cell splenocytes (P < 0.05) and the percentage of B-cells increased on day 14 PI in the spleen and on day 28 PI in the lymph nodes (P < 0.05). By day 28 PI, the number of B-cell splenocytes decreased significantly. A non-subset-specific decrease in percentages of CD4 lymphocytes throughout all lymphoid organs was observed on day 14 PI. However, total CD4 and CD44/CD4 splenocytes increased significantly by day 28 PI. Early-activation CD8 lymphocytes were reduced in the blood and spleen, whereas memory CD8 lymphocyte percentages and total numbers were significantly increased. On the basis of the results, we propose that S. neurona-infected IFN-gamma KO mice are immunocompromised and unable to clear the infection. Thus, they develop B-cell exhaustion and a delayed, but sustained, increased number of memory CD4 and CD8 lymphocytes due to chronic antigen stimulation.
authors: Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061-0442, USA. switonsk@vt.edu
authors: Sharon G
authors: SG
authors: Witonsky
authors: Robert M
authors: RM
authors: Gogal
authors: Robert B
authors: RB
authors: Duncan
authors: David S
authors: DS
authors: Lindsay
mesh_terms: D000372:Agglutination Tests; D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis* / Q000097:blood; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D001921:Brain / Q000473:pathology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology*; D008099:Liver / Q000473:pathology; D008168:Lung / Q000473:pathology; D008198:Lymph Nodes / Q000276:immunology / Q000473:pathology; D018655:Lymphocyte Count; D051379:Mice; D018345:Mice, Knockout; D012522:Sarcocystis / Q000276:immunology*; D012523:Sarcocystosis / Q000276:immunology* / Q000473:pathology*; D013154:Spleen / Q000276:immunology / Q000473:pathology
chemical_list: D000913:Antibodies, Protozoan; D007371:Interferon-gamma