title: Lymphocyte subset proliferative responses of Mycobacterium bovis-infected cattle to purified protein derivative.
abstract: Despite highly successful eradication efforts in several countries, Mycobacterium bovis infection of cattle remains a significant health concern worldwide. Immune mechanisms of resistance to and/or clearance of M. bovis infection of cattle, however, are unclear. Recent studies have provided evidence supporting a role for CD4(+), CD8(+), and gammadelta TCR(+) T cells in the response of cattle to M. bovis. In the present study, we utilized a flow cytometric-based proliferation assay to determine the relative contribution of individual lymphocyte subsets in the response to M. bovis infection and/or sensitization with mycobacterial purified protein derivative (PPD). Peripheral blood mononuclear cells (PBMC) from M. bovis-infected cattle proliferated in response to in vitro stimulation with M. bovis PPD. CD4(+) T cells and gammadelta TCR(+) cells were the predominate subsets of lymphocytes responding to PPD. gammadelta TCR(+) cells also proliferated in non-stimulated cultures; however, the gammadelta TCR(+) cell proliferative response of infected cattle was significantly (p<0.05) greater in PPD-stimulated cultures as compared to non-stimulated cultures. Intradermal injection of PPD for comparative cervical testing (CCT) induced a boost in the in vitro proliferative response of CD4(+) but not gammadelta TCR(+) cells of infected cattle. Administration of PPD for CCT also boosted interferon-gamma (IFN-gamma) production by PBMC of infected cattle following in vitro stimulation with M. bovis PPD. Injection of PPD for CCT did not, however, elicit a proliferative or IFN-gamma response in cells isolated from non-infected cattle. These data indicate that CD4(+) and gammadelta TCR(+) cells of M. bovis-infected cattle proliferate in a recall response to M. bovis PPD and that the CD4(+) cell response is boosted by intradermal injection with PPD for CCT.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, National Animal Disease Center, Bacterial Diseases of Livestock Unit, PO Box 70, Ames, IA 50010-0070, USA. rwaters@nadc.ars.usda.gov
authors.forename: W R
authors.initials: WR
authors.lastname: Waters
authors.forename: M V
authors.initials: MV
authors.lastname: Palmer
authors.forename: B A
authors.initials: BA
authors.lastname: Pesch
authors.forename: S C
authors.initials: SC
authors.lastname: Olsen
authors.forename: M J
authors.initials: MJ
authors.lastname: Wannemuehler
authors.forename: D L
authors.initials: DL
authors.lastname: Whipple
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002417:Cattle; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000032:analysis; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D014373:Tuberculin / Q000276:immunology*; D014380:Tuberculosis, Bovine / Q000276:immunology*
chemical_list: D016692:Receptors, Antigen, T-Cell, gamma-delta; D014373:Tuberculin; D007371:Interferon-gamma