A humanised therapeutic CD4 mAb inhibits TCR-induced IL-2, IL-4, and IL-10 secretion and expression of CD25, CD40L, and CD69.
The actions of a humanised therapeutic CD4 mAb YHB.46 on T cell activation were investigated in vitro. Soluble YHB.46 IgG or YHB.46-derived F(ab')2 fragments caused inhibitions of up to 100% of the proliferation of purified CD4+ T cells activated with immobilised CD3 mAb. The inhibitory effects of the CD4 mAb were equally potent in both CD45RA+ and CD45RO+ T cell subset proliferation assays. Inhibitory effects on DNA synthesis were nto explicable by increased T cell apoptosis. YHB.46 was inhibitory even when added 70 h after exposure of cells to immobilised CD3 mAb, but it had little effect on IL-2 receptor-driven proliferation signals. The CD4 mAb inhibited the CD3-induced expression of the CD25 and CD69 activation markers on the T cell surface and suppressed CD40 ligand expression, but not that of CD25 and CD69, when their expression was induced by phorbol ester plus ionomycin. YHB.46 also exerted a profound inhibitory effect on the production of IL-2, IL-4, and IL-10, irrespective of whether T cells were activated with CD3 mAb or with phorbol ester plus ionomycin. The inhibitory effects of YHB.46 on CD4+ T cell proliferation were partially prevented by the addition of exogenous IL-2 or autologous monocytes and were completely prevented by activating T cells with a novel CD3-CD28 bivalent F(ab')2 reagent. However, the inhibitory effects of YHB.46 on T cell proliferation were equipotent in the presence or the absence of CTLA-4Ig, showing that the CD4 mAb was not acting on CD28-induced activation signals per se. Our results show that the inhibitory effects of YHB.46 on T cell activation do not involve CD28 or IL-2 receptor signalling, but are directed at the TCR-mediated G0-G1 transition. These findings in vitro predict that YHB.46 may act as a potent immunosuppressant in the clinical context.
Woods
M
M
Department of Immunology, Babraham Institute, Cambridge, United Kingdom.
Guy
R
R
Waldmann
H
H
Glennie
M
M
Alexander
D R
DR
D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000494:pharmacology* / Q000627:therapeutic use; D015703:Antigens, CD / Q000096:biosynthesis*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis*; D001666:Binding Sites, Antibody / Q000187:drug effects; D001667:Binding, Competitive; D018106:CD28 Antigens / Q000502:physiology; D017252:CD3 Complex / Q000502:physiology; D015704:CD4 Antigens / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D019013:CD40 Antigens / Q000378:metabolism; D023201:CD40 Ligand; D016207:Cytokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D016753:Interleukin-10 / Q000037:antagonists & inhibitors / Q000378:metabolism; D007376:Interleukin-2 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D015847:Interleukin-4 / Q000037:antagonists & inhibitors / Q000378:metabolism; D007378:Interleukins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D037181:Lectins, C-Type; D008024:Ligands; D008213:Lymphocyte Activation / Q000276:immunology; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D008565:Membrane Proteins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D016853:Muromonab-CD3 / Q000494:pharmacology; D010766:Phosphorylation; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism / Q000502:physiology*; D011961:Receptors, Fc / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D014443:Tyrosine / Q000378:metabolism; D015854:Up-Regulation / Q000276:immunology; D000099192:CD69 Antigens
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D018106:CD28 Antigens; D017252:CD3 Complex; D015704:CD4 Antigens; D019013:CD40 Antigens; D023201:CD40 Ligand; D016207:Cytokines; D007166:Immunosuppressive Agents; D016753:Interleukin-10; D007376:Interleukin-2; D015847:Interleukin-4; D007378:Interleukins; D037181:Lectins, C-Type; D008024:Ligands; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D016853:Muromonab-CD3; D011948:Receptors, Antigen, T-Cell; D011961:Receptors, Fc; D015375:Receptors, Interleukin-2; D014443:Tyrosine; D000099192:CD69 Antigens; C054979:antigen T cell receptor, zeta chain