Monoclonal antibody analysis of diphtheria toxin--I. Localization of epitopes and neutralization of cytotoxicity

Mol Immunol. 1984 Sep;21(9):785-93. doi: 10.1016/0161-5890(84)90165-2.


Forty-three hybridoma cell lines producing monoclonal antibody to diphtheria toxin were isolated. Based upon their reactivity with various fragments of the toxin and mutant toxin-related proteins, the monoclonal antibodies were subdivided into 10 groups which recognize at least 10 distinct epitopes on the toxin molecule. Specific antibodies directed against both fragments A and B were found to neutralize cytotoxicity, both in vitro and in vivo. Neutralization was found to correlate with antibody-mediated inhibition of toxin binding to its eukaryotic cell surface receptor. The results presented suggest that the Pro378 and/or Gly431 of mature toxin are part of, or close to, the toxin receptor-binding domain. In addition, antigenic determinants in the C-terminal portion of fragment A, as well as a portion of the toxin defined by the tox-3 and tox-45 nonsense mutations (i.e. ca 31,000-42,000 daltons) appear to be juxtaposed to the receptor-binding domain and may form a secondary binding region.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / immunology
  • Cell Line
  • Cricetinae
  • Cross Reactions
  • Cytotoxicity, Immunologic
  • Diphtheria Toxin / immunology*
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes / immunology
  • Hybridomas / immunology
  • Immunoglobulin Fab Fragments / immunology
  • Immunoglobulin G / immunology
  • Mice
  • Neutralization Tests


  • Antibodies, Monoclonal
  • Diphtheria Toxin
  • Epitopes
  • Immunoglobulin Fab Fragments
  • Immunoglobulin G