title: Spectratype analysis of the T cell receptor δ CDR3 region of bovine γδ T cells responding to leptospira.
abstract: Gamma delta T cells comprise the majority of blood T cells in ruminants at birth and remain at high levels for several years with most expressing the WC1 co-receptor. A subpopulation of Bos taurus WC1(+) cells expressing a restricted set of WC1 molecules respond immediately by proliferation and interferon-γ production to leptospira following vaccination, preceding the response by CD4 T cells. Our goal is to define the γδ T cell recognition elements involved. Previously, we showed that the responding cells employed a variety of TRDV genes indicating that the CDR1 and CDR2 of TCRδ could vary and may not be principally involved in antigen specificity. Murine and human γδ T cells bind T22 and self lipids through their CDR3δ. Like mice, cattle use up to five TRDD genes in a single CDR3δ adding flexibility to length and configuration for antigen binding. Here, we used spectratyping to evaluate the CDR3δ of leptospira-responsive cells. Little or no compartmentalization of CDR3δ was found for antigen-responsive cells that incorporated TRDV1, TRDV2, or TRDV3 even though they comprise the majority of the leptospira-responding population. Compartmentalization occurred for TRDV4-containing transcripts and was maintained over time and among cattle. However, no common amino acid motif was apparent in those CDR3δ sequences, although a bias in D gene usage occurred. We hypothesize that the restricted set of WC1 co-receptors expressed by the responding cells may lend specificity to the response through their ability to bind bacteria facilitating interaction of various TCRs with bacterial components resulting in cross-linking and activation.
authors.affiliation: Department of Veterinary and Animal Sciences, University of Massachusetts, Integrated Sciences Building, 661 N. Pleasant St, Amherst, MA, 01003, USA.
authors.forename: Carolyn T A
authors.initials: CT
authors.lastname: Herzig
authors.forename: Vanessa L
authors.initials: VL
authors.lastname: Mailloux
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Baldwin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000942:Antigens, Bacterial; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000382:microbiology*; D002417:Cattle / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D022801:Complementarity Determining Regions / Q000737:chemistry / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D019676:Genes, T-Cell Receptor delta; D006801:Humans; D007919:Leptospira / Q000276:immunology* / Q000472:pathogenicity; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid
chemical_list: D000942:Antigens, Bacterial; D022801:Complementarity Determining Regions; C086500:DMBT1 protein, Bos taurus; D017931:DNA Primers; D008562:Membrane Glycoproteins; D016692:Receptors, Antigen, T-Cell, gamma-delta