title: Chicken CRTAM binds nectin-like 2 ligand and is upregulated on CD8+ αβ and γδ T lymphocytes with different kinetics.
abstract: During a search for immunomodulatory receptors in the chicken genome, we identified a previously cloned chicken sequence as CRTAM homologue by its overall identity and several conserved sequence features. For further characterization, we generated a CRTAM specific mab. No staining was detectable in freshly isolated cell preparations from thymus, bursa, caecal tonsils, spleen, blood and intestine. Activation of splenocytes with recombinant IL-2 increased rapid CRTAM expression within a 2 h period on about 30% of the cells. These CRTAM(+) cells were identified as CD8(+) γδ T lymphocytes. In contrast, CRTAM expression could not be stimulated on PBL with IL-2, even within a 48 h stimulation period. As a second means of activation, T cell receptor (TCR) crosslinking using an anti-αβ-TCR induced CRTAM on both PBL and splenocytes. While CRTAM expression was again rapidly upregulated on splenocytes within 2 h, it took 48 h to reach maximum levels of CRTAM expression in PBL. Strikingly, albeit the stimulation of splenocytes was performed with anti-αβ-TCR, CRTAM expression after 2 h was mainly restricted to CD8(+) γδ T lymphocytes, however, the longer anti-TCR stimulation of peripheral blood lymphocytes (PBL) resulted in CRTAM expression on αβ T lymphocytes. In order to characterize the potential ligand we cloned and expressed chicken Necl-2, a member of the nectin and nectin-like family which is highly homologous to its mammalian counterpart. Three independent assays including a reporter assay, staining with a CRTAM-Ig fusion protein and a cell conjugate assay confirmed the interaction of CRTAM with Necl-2 which could also be blocked by a soluble CRTAM-Ig fusion protein or a CRTAM specific mab. These results suggest that chicken CRTAM represents an early activation antigen on CD8(+) T cells which binds to Necl-2 and is upregulated with distinct kinetics on αβ versus γδ T lymphocytes.
authors: Institute for Animal Physiology, Department of Veterinary Sciences, University of Munich, Munich, Germany.
authors: Maria
authors: M
authors: Zechmann
authors: Sven
authors: S
authors: Reese
authors: Thomas W
authors: TW
authors: Göbel
mesh_terms: D000818:Animals; D030161:Avian Proteins / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002645:Chickens; D005786:Gene Expression Regulation / Q000276:immunology*; D057809:HEK293 Cells; D006801:Humans; D007136:Immunoglobulins / Q000276:immunology*; D008213:Lymphocyte Activation; D011485:Protein Binding / Q000276:immunology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology*; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013997:Time Factors
chemical_list: D030161:Avian Proteins; D007136:Immunoglobulins; D016693:Receptors, Antigen, T-Cell, alpha-beta; D016692:Receptors, Antigen, T-Cell, gamma-delta; C408522:class-I restricted T cell-associated molecule