title: CD45RO expression on bovine T cells: relation to biological function.
abstract: The 180,000 MW isoform of CD45 (CD45RO) has been identified in cattle with a novel monoclonal antibody (mAb) (IL-A116). This has allowed a more precise analysis of T-cell function in relation to CD45 isoform expression. Within the CD4+ and CD8+ T-cell populations, CD45RO+ and CD45RO- subsets were evident. Most CD4+ and CD8+ T cells that expressed the CD45RO isoform did not express the 220,000 and 205,000 MW isoforms recognized by mAb CC76. In contrast, the WC1+, CD2-, CD4-, CD8-, gamma delta T-cell receptor (TCR)+ T cells in bovine peripheral blood mononuclear cells (PBMC) were all CD45RO+. Monocytes and granulocytes were CD45RO+ but B cells were CD45RO-. Sorting experiments with CD4+ T cells from an immunized calf demonstrated that proliferative responses to ovalbumin (OVA) were entirely within the CD45RO+ subset. Following stimulation with concanavalin A (Con A) the CD45RO- subset of CD4+ T cells produced transcripts for interleukin-2 (IL-2) but not IL-4 or interferon-gamma (IFN-gamma), while the CD45RO+ subset produced mRNA for IL-2, IL-4 and IFN-gamma. Biologically active IL-2 was present in supernatants from both CD45RO+ and CD45RO-, CD4+ T cells, and IFN-gamma protein was identified by ELISA in supernatants from the CD45RO+ subset, confirming the production of cytokines implied by polymerase chain reaction (PCR). In contrast, sorting experiments with CD8+ T cells from animals immune to the protozoan parasite Theileria parva revealed substantial numbers of cytotoxic T-lymphocyte precursors in both the CD45RO+ and CD45RO- subsets. Thus it appears that although all antigenically primed CD4+ T cells remain CD45RO+, and expression of this molecule consequently identifies memory cells within PBMC, antigenically primed CD8+ T cells down-regulate CD45RO expression after activation.
authors.affiliation: Institute for Animal Health, Compton Laboratory, UK.
authors.forename: G P
authors.initials: GP
authors.lastname: Bembridge
authors.forename: N D
authors.initials: ND
authors.lastname: MacHugh
authors.forename: D
authors.initials: D
authors.lastname: McKeever
authors.forename: E
authors.initials: E
authors.lastname: Awino
authors.forename: P
authors.initials: P
authors.lastname: Sopp
authors.forename: R A
authors.initials: RA
authors.lastname: Collins
authors.forename: K I
authors.initials: KI
authors.lastname: Gelder
authors.forename: C J
authors.initials: CJ
authors.lastname: Howard
mesh_terms: D000818:Animals; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D002417:Cattle / Q000276:immunology*; D002455:Cell Division / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D007371:Interferon-gamma / Q000096:biosynthesis; D007378:Interleukins / Q000096:biosynthesis; D017493:Leukocyte Common Antigens / Q000097:blood*; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D007378:Interleukins; D007371:Interferon-gamma; D017493:Leukocyte Common Antigens