The generation of a humanized, non-mitogenic CD3 monoclonal antibody which retains in vitro immunosuppressive properties

Eur J Immunol. 1993 Feb;23(2):403-11. doi: 10.1002/eji.1830230216.

Abstract

CD3 antibodies are proven immunosuppressants capable of reversing transplant rejection episodes. Their general application has been limited both by their immunogenicity and, in particular, by the "first-dose" cytokine-release syndrome experienced by patients after the initial administration of antibody. We have produced a set of variants of the humanized YTH 12.5 CD3 monoclonal antibody (mAb) (Routledge et al., Eur. J. Immunol. 1991. 21: 2717) bearing different human heavy (H) chain constant regions, with the intention of finding a form of the antibody that is not able to activate T cells. Comparison of the variants having gamma 1, gamma 2, gamma 3 and gamma 4 H chains in a competitive binding assay showed that antibody avidity was not affected by IgG subclass. Using a sensitive indicator of FcR binding activity (the capacity of the CD3 mAb to redirect cytotoxic T cells to kill the monocytic cell line U-937) we demonstrated a functional hierarchy of gamma 1 = gamma 4 > alpha 2 =/> gamma 3 mb >> gamma 2. An aglycosyl version of the gamma 1 CD3 mAb, produced by site-directed mutagenesis (Asn297 to Ala), still had considerable activity in this assay (intermediate to the gamma 1 and alpha 2 CD3 mAb), albeit at a level approximately 10-fold lower than that of the parental gamma 1 form. When we tested their ability to stimulate T cell proliferation in vitro in the presence of 5% human serum, all of the wild-type immunoglobulin isotypes were found to be active, although there were T cell donor-dependent variations in the extent of the responses. The aglycosyl gamma 1 mAb was, however, completely non-mitogenic in all of ten donors tested, unless the assay was performed in IgG-free medium. Despite being non-stimulatory, this mAb was also able to inhibit the mixed lymphocyte reaction responses of both naive and primed T cells. Comparison of the gamma 1 and aglycosyl gamma 1 mAb in an experimental mouse model for CD3 mAb-induced cytokine release indicated that removal of the carbohydrate moiety from the gamma 1 constant region reduced the in vivo tumor necrosis factor-alpha response by a factor of at least 16-fold. These data suggest that the aglycosyl gamma 1 CD3 mAb is a promising candidate for immunosuppressive therapy without "first dose" side effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / biosynthesis
  • Antibodies, Monoclonal / immunology*
  • CD3 Complex / immunology*
  • CHO Cells
  • Cell Line
  • Cricetinae
  • Cytokines / metabolism
  • Cytotoxicity, Immunologic / immunology
  • Genes, Immunoglobulin / immunology
  • Glycosylation
  • Humans
  • Immunoglobulin Heavy Chains / immunology
  • Immunosuppression*
  • Lymphocyte Activation / immunology
  • Mitogens
  • Mutagenesis, Site-Directed
  • T-Lymphocytes / immunology
  • Transfection

Substances

  • Antibodies, Monoclonal
  • CD3 Complex
  • Cytokines
  • Immunoglobulin Heavy Chains
  • Mitogens