The immunogenicity of antibody aggregates in a novel transgenic mouse model

Pharm Res. 2015 Jul;32(7):2344-59. doi: 10.1007/s11095-015-1627-0. Epub 2015 Jan 29.

Abstract

Purpose: Protein aggregates have been discussed as a potential risk factor related to immunogenicity. Here we developed a novel human IgG transgenic (tg) mouse system expressing a mini-repertoire of human IgG1 antibodies (Abs) for the assessment of immunogenic properties of human mAb preparations.

Methods: Transgenic mice were generated using germline versions of the human Ig heavy chain γ1 (IgH-γ1), and the human Ig light chain (IgL) κ and λ genes. Only the soluble form of human IgH-γ1 was used to avoid expression of the membrane Ig-H chain and concomitant allelic exclusion of endogenous murine Ig genes. IgG1 aggregates were generated by different stress conditions such as process-related, low pH and exposure to artificial light.

Results: The expression of human Ig proteins induced immunological tolerance to a broad range of human IgG1 molecules in the tg mice. Immunization with IgG1 aggregates demonstrated that soluble oligomers induced by significant light-exposure and carrying neo-epitopes induced a strong immune response in tg mice. In contrast, Ab aggregates alone and monomers with neo-epitopes were not immunogenic.

Conclusion: This mouse model is able to recognize immunogenic modifications of human IgG1. While the degree of stress-induced aggregation varies for different mAbs, our findings using a particular mAb (mAb1) demonstrate that non-covalently modified aggregates do not break tolerance, contrary to widely held opinion. The immunogenic potential of soluble aggregates of human IgG strongly depends on the presence of neo-epitopes resulting from harsh stress conditions, i.e. extensive exposure to artificial light.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Monoclonal / genetics
  • Antibodies, Monoclonal / immunology*
  • Antibody Formation
  • Base Sequence
  • Flow Cytometry
  • Humans
  • Immune Tolerance
  • Immunoglobulin G / genetics
  • Immunoglobulin G / immunology*
  • Immunoglobulin Heavy Chains / genetics
  • Immunoglobulin Heavy Chains / immunology
  • Immunoglobulin Light Chains / genetics
  • Immunoglobulin Light Chains / immunology
  • Mice, Transgenic / genetics
  • Mice, Transgenic / immunology*
  • Molecular Sequence Data
  • Protein Aggregates / genetics
  • Protein Aggregates / immunology*
  • Stress, Psychological / immunology
  • Transgenes

Substances

  • Antibodies, Monoclonal
  • Immunoglobulin G
  • Immunoglobulin Heavy Chains
  • Immunoglobulin Light Chains
  • Protein Aggregates