Effects of the depletion of CD8(+) T cells and monocytes on the proliferative responses of peripheral blood leucocytes from Trypanosoma evansi-infected sheep.
Sheep peripheral blood mononuclear cells and those depleted of CD8(+) T cells and/or monocytes were stimulated with polyclonal mitogens and specific antigens, and analysed by means of cell proliferation assay procedure to examine whether these cell populations are involved in Trypanosoma evansi-induced immunosuppression. The removal of CD8(+) T cells failed to normalize the proliferative responses of peripheral blood mononuclear cells from infected sheep to concanavalin A stimulation while the depletion of monocytes resulted in full and enhanced response, showing that macrophages are mainly responsible for the suppression. Although the depletion of CD8(+) T cells, monocytes or both restored the responses of the cells to lipopolysaccharide stimulation, the responsiveness of the undepleted cells to this mitogen was significantly higher from day 24 post infection (p<0.01). The results were discussed in relation to current known mechanisms of depressed lymphocyte proliferation in tsetse-transmitted African trypanosome infections.
Onah
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DN
Centre for Tropical Veterinary Medicine, University of Edinburgh, Scotland, Edinburgh, UK. denis@fc.miyazaki-med.ac.jp
Hopkins
J
J
Luckins
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AG
D000818:Animals; D000942:Antigens, Bacterial / Q000494:pharmacology; D000953:Antigens, Protozoan / Q000494:pharmacology; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D009000:Monocytes / Q000502:physiology*; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology*; D014352:Trypanosomiasis / Q000662:veterinary*
D000942:Antigens, Bacterial; D000953:Antigens, Protozoan; D008070:Lipopolysaccharides; D003208:Concanavalin A