title: Construction and characterization of a humanized anti-human CD3 monoclonal antibody 12F6 with effective immunoregulation functions.
abstract: 12F6 is a murine anti-human CD3 monoclonal antibody, which competes with OKT3 for binding to human T cells and possesses more effective T-cell suppression and activation properties compared to OKT3. It thus exhibits the potential to be developed as an immunoregulation agent for manipulating T-cell functions and preventing acute allograft rejection. In an attempt to minimize the immunogenicity of murine 12F6 (m12F6) for potential clinical application, a humanized version of 12F6, denoted as hu12F6, was successfully constructed by complementary determining region (CDR) grafting and shown to maintain both T-cell activation and suppression activities similar to m12F6. Furthermore, in order to reduce the first dose reaction syndrome caused by T-cell activation following the first administration of anti-CD3 antibodies, two amino acid mutations were introduced into the Fc region of hu12F6, resulting in the Fc-mutated 12F6 humanized antibody (hu12F6mu). This Fc-mutated version displayed a similar antigen-binding affinity and specificity compared with hu12F6 and m12F6 but with much weaker FcR binding activity. hu12F6mu was shown to be much less potent in the induction of T-cell proliferation, cytokine release (tumour necrosis factor-alpha, interferon-gamma and interleukin-10) and early activation marker expression on the cell surface (CD69 and CD25) than parental 12F6 and OKT3 did. In contrast, hu12F6mu was effective in modulating T-cell receptor/CD3 and inhibiting mixed lymphocyte reaction with a similarity as compared to m12F6 and OKT3. In conclusion, the resultant hu12F6mu was much less mitogenic to T cells but retained potent immunosuppression, suggesting it might be an alternative to OKT3 as an immunosuppressive drug with less immunogenicity and toxicity for clinical application.
authors.affiliation: International Joint Cancer Institute and Shanghai E-Institutes Immunology Division, Second Military Medical University, PR China.
authors.forename: Bohua
authors.initials: B
authors.lastname: Li
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.forename: Jianxin
authors.initials: J
authors.lastname: Dai
authors.forename: Junjie
authors.initials: J
authors.lastname: Ji
authors.forename: Weizhu
authors.initials: W
authors.lastname: Qian
authors.forename: Dapeng
authors.initials: D
authors.lastname: Zhang
authors.forename: Sheng
authors.initials: S
authors.lastname: Hou
authors.forename: Yajun
authors.initials: Y
authors.lastname: Guo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology*; D000915:Antibody Affinity; D001667:Binding, Competitive; D017252:CD3 Complex / Q000276:immunology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008969:Molecular Sequence Data; D016853:Muromonab-CD3 / Q000276:immunology; D011961:Receptors, Fc / Q000235:genetics / Q000276:immunology; D011993:Recombinant Fusion Proteins / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D017252:CD3 Complex; D016207:Cytokines; D016853:Muromonab-CD3; D011961:Receptors, Fc; D011993:Recombinant Fusion Proteins