THE EFFECT OF AGLYCOSYLATION ON THE IMMUNOGENICITY OF A... : Transplantation (original) (raw)

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THE EFFECT OF AGLYCOSYLATION ON THE IMMUNOGENICITY OF A HUMANIZED THERAPEUTIC CD3 MONOCLONAL ANTIBODY

ROUTLEDGE, EDWARD G.; FALCONER, MARGARET E.; POPE, HEATHER; LLOYD, IRENE S.; WALDMANN, HERMAN

Division of Immunology, Department of Pathology, Cambridge University, Cambridge CH2 IQP, United Kingdom

2 Division of Virology, School of Pathological Sciences, The Medical School, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, U.K.

3 Division of Immunology, Cambridge University Department of Pathology, Tennis Court Road, Cambridge CB2 1QP, U.K.

4 Cantab Pharmaceuticals Research Ltd., 184 Cambridge Science Park, Milton Road, Cambridge CB4 4GN, U.K.

5 Address correspondence to Professor Herman Waldmann, Sir William Dunn School of Pathology, South Parks Road, Oxford 0X1 3RE, U.K.

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Abstract

The factors affecting the immunogenicity of a humanized γ1 CD3 monoclonal antibody (mAb) were investigated in transgenic mice that express the human CD3 antigen epsilon polypeptide (the mAb target antigen). Two derivatives of the mAb were employed, one with a normal, glycosylated Fc region (γ1 CD3 mAb), and the other with an aglycosylated Fc region (aglycosyl γ1 CD3 mAb). Comparisons of the antiglobulin responses elicited by the two derivatives in transgenic and nontransgenic mice demonstrated that Fab-mediated cell binding activity, dependent on target antigen expression, was a major positive determinant of CD3 mAb immunogenicity. A second positive factor was mAb Fc region glycosylation. At low dose levels the γ1 CD3 mAb consistently produced a higher antiglobulin response than the aglycosyl γ1 CD3 mAb. This was probably a result of the nonspecific, in vivo T cell activating property of the γ1 CD3 mAb, a consequence of its ability to cross-link T cells to Fcγ receptor-bearing cells. (The aglycosyl γ1 CD3 mAb has a reduced Fc binding affinity for Fcγ receptors and so does not activate T cells in vivo.) In support of this hypothesis, the γ1 CD3 mAb was able to nonspecifically enhance humoral immunity to an unrelated, coadministered antigen, whereas the aglycosyl γ1 CD3 mAb was not. The lower immunogenicity of the aglycosyl γ1 CD3 mAb correlated with a longer in vivo half-life and an improved capacity to block the target CD3 antigen. These results suggest that, as well as reducing the cytokine-induced side effects normally associated with CD3 mAb therapy, the nonactivating aglycosyl γ1