Production and characterization of human monoclonal antibody recognizing the N-terminal residues of Pseudomonas aeruginosa exotoxin A.

Human cell lines producing monoclonal antibodies (MAbs) against Pseudomonas aeruginosa exotoxin A were established by EBV transformation followed by cell fusion. Monoclonal antibody FK-001, IgM (mu, kappa), was demonstrated to be specifically reactive with exotoxin A in ELISA and immunoblotting, by recognizing N-terminal 16 amino acid residues of exotoxin A as an epitope. This epitope region belongs to domain I which is required for the binding of exotoxin A to the receptor on target cells. FK-001 showed a partial neutralizing activity for cell toxicity caused by exotoxin A and appeared to be effective against exotoxin A-producing P. aeruginosa infection in mice. A line of evidence suggests that monoclonal antibody FK-001 neutralizes exotoxin A-induced cell toxicity by the interference of accessibility and/or binding of exotoxin A to animal cell receptors.