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Antagonist properties of monoclonal antibodies to human CD28: role of valency and heavy-chain constant domain

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Journal of Translational Medicine201210 (Suppl 3) :P17

  • Published:


  • Polyethylene Glycol
  • Constant Domain
  • Agonist Property
  • Antagonist Property
  • CD80 Interaction


Antagonist antibodies targeting CD28 have been proposed as an alternative to the use of CD80/86 antagonists to modulate T cell responses in autoimmunity and transplantation. Advantages would be the blockade of CD28-mediated co-stimulatory signals without impeding co-inhibitory signals depending on CD80 interactions with CTLA-4 and PD-L1 that are important for the control of immune responses and for the function of regulatory T cells. Anti-CD28 antibodies are candidate antagonists only if they prevent access to the CD80/86 ligands without simultaneously stimulating CD28 itself, a process that is believed to depend on receptor multimerization.

Methods and results

In this study, we used different formats of a potentially antagonist anti-human CD28 antibody and evaluated the impact on T cell activation of valency and of the presence of a fragment cristallisable (Fc) domain, two components that might impact receptor multimerization either directly or in the presence of accessory cells expressing Fc receptors. Among monovalent (Fab’, scFv), divalent (Fab’2), monovalent-Fc (Fv-Fc) and divalent-Fc (IgG) formats, only the monovalent formats showed consistent absence of induced CD28 multimerization and of associated activation of Phospho Inositol-3 Kinase as well as clear antagonist properties in T cell stimulation assays. In contrast divalent antibodies showed agonist properties resulting in cell proliferation and cytokine release, in a Fc-independent manner. Conjugation of monovalent antibodies with polyethylene glycol, with a molecule of alpha-1-antitrypsin or with an Fc domain significantly extended their in vivo half-life without modifying antagonist properties.


These data indicate that monovalency is mandatory for maintaining antagonistic activity of anti-CD28 monoclonal antibodies.

Authors’ Affiliations

Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche-Santé 1064, Nantes, France
Effimune SAS, Nantes, France
Institut de Transplantation Urologie Néphrologie, Centre Hospitalier Universitaire de Nantes, Université de Nantes, Nantes, France


© Mary et al; licensee BioMed Central Ltd. 2012

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.