title: An in vivo model to investigate lymphocyte-mediated immunity during acute hemoparasitic infections. Use of a monoclonal antibody to selectively deplete CD4+ T lymphocytes from thymectomized calves.
abstract: Thymectomized calves were selectively depleted of CD4+ T lymphocytes with a monoclonal antibody (mAb) specific for the bovine CD4 monomer (ILA-11). Calves were treated with high loading doses of ILA-11 during the first week of the study then treated with subsequent lower maintenance doses. Depletion of CD4+ T lymphocytes was assessed weekly by flow cytometric analysis of PBMC and mononuclear cells from lymph node and spleen biopsies. Treatment with high doses of ILA-11 resulted in rapid and marked depletion of CD4+ T lymphocytes from the peripheral blood, peripheral lymph nodes, and spleen. Although CD4+ T lymphocytes slowly returned to the peripheral blood, peripheral lymph nodes, and spleen by day 21 post-treatment, the numbers of CD4+ T lymphocytes in depleted calves remained below pre-depletion levels for the duration of the study. CD4+ T lymphocytes failed to be effectively depleted from a non-thymectomized calf treated with the mAb ILA-11. Development of a T lymphocyte depletion model in thymectomized calves will permit testing of the hypothesis that CD4+ T lymphocytes and IFN-gamma are required in cattle for control of acute anaplasmosis. In subsequent planned studies, thymectomized calves depleted of CD4+ T lymphocytes will be experimentally infected with A. marginale and parameters of disease compared between depleted and non-depleted calves.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Animal Disease Research Unit, P.O. Box 646630, Pullman, WA 99164-6630, USA. reg@vetmed.wsu.edu
authors.forename: R A
authors.initials: RA
authors.lastname: Valdez
authors.forename: T C
authors.initials: TC
authors.lastname: McGuire
authors.forename: W C
authors.initials: WC
authors.lastname: Brown
authors.forename: W C
authors.initials: WC
authors.lastname: Davis
authors.forename: D P
authors.initials: DP
authors.lastname: Knowles
mesh_terms: D000712:Anaplasmosis / Q000276:immunology*; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002417:Cattle; D007111:Immunity, Cellular; D008198:Lymph Nodes / Q000276:immunology; D008212:Lymphocyte Depletion / Q000379:methods*; D013154:Spleen / Q000276:immunology; D013934:Thymectomy
chemical_list: D000911:Antibodies, Monoclonal