title: Altered proximal T-cell receptor signalling events in mouse CD4+ T cells in the presence of anti-CD4 monoclonal antibodies: evidence for reduced phosphorylation of Zap-70 and LAT.
abstract: Anti-CD4 monoclonal antibodies are potential therapeutic agents for the prevention of autoimmune disease and treatment of rejection after organ transplantation and are capable of both restoring tolerance to self-antigens and inducing tolerance to antigens introduced under the cover of the antibody therapy in vivo. Tolerance to donor alloantigens can be induced in vivo by administering donor alloantigen in combination with either depleting (YTA 3.1) or nondepleting (YTS 177) anti-CD4, 28 days before heart transplantation in the mouse. The effect of anti-CD4 on proximal T-cell receptor (TCR) signalling pathways and proliferation was investigated in vitro and in vivo in the presence and absence of YTA 3.1 or YTS 177. Anti-CD4 was found to perturb proximal signalling events upon TCR/CD3 ligation, resulting in reduced tyrosine phosphorylation of Zap-70 and LAT (linker for activation of T cells) and reduced association of tyrosine-phosphorylated LAT with lck. This ultimately resulted in severely reduced proliferation of the responding CD4+ T cells. The signalling profile of the anti-CD4-treated cells resembled that of anergic T cells. This could be a result of a common mechanism involving perturbation in the formation of the central supramolecular activation cluster of the immunological synapse by impaired recruitment of CD4 and CD28, thereby resulting in severely reduced lck activation.
authors.affiliation: Nuffield Department of Surgery, University of Oxford, John Radcliffe Hospital, Oxford, UK.
authors.forename: C E
authors.initials: CE
authors.lastname: Pullar
authors.forename: P J
authors.initials: PJ
authors.lastname: Morris
authors.forename: K J
authors.initials: KJ
authors.lastname: Wood
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000494:pharmacology; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D002455:Cell Division / Q000276:immunology; D005260:Female; D015759:Ionomycin / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000276:immunology; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D010750:Phosphoproteins / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000276:immunology / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D015375:Receptors, Interleukin-2 / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D002352:Carrier Proteins; C491734:Lat protein, mouse; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D015375:Receptors, Interleukin-2; D015759:Ionomycin; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; C497262:Zap70 protein, mouse; D013755:Tetradecanoylphorbol Acetate