Monoclonal antibody analysis of diphtheria toxin--I. Localization of epitopes and neutralization of cytotoxicity.
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.
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002460:Cell Line; D006224:Cricetinae; D003429:Cross Reactions; D003602:Cytotoxicity, Immunologic; D004167:Diphtheria Toxin / Q000276:immunology*; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes / Q000276:immunology; D006825:Hybridomas / Q000276:immunology; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D009500:Neutralization Tests
D000911:Antibodies, Monoclonal; D004167:Diphtheria Toxin; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G