Human IgG and murine monoclonal antibodies share common idiotopes as determined by competitive binding to polystyrene and nitrocellulose-bound antigens.

Competitive binding to polystyrene-bound antigens showed that human rye Group I (rye I)-specific IgG recognize the same three distinct epitopes of rye I as three monoclonal antibodies directed against the same antigens. Anti-idiotypic antibodies against one of the monoclonal antibodies (290A-167) inhibit completely the reaction between rye I and the relevant monoclonal antibodies but do not affect the reaction between other monoclonal antibodies (348A-6 and 539A-6) and the antigens. Furthermore, rabbit anti-idiotypic antibodies produced against F(ab' )2 of human rye I-specific IgG could inhibit the reaction between two monoclonal antibodies (290A-167 and 539A-6) and the relevant antigens. Those results were obtained by competitive binding to polystyrene or to nitrocellulose-bound antigens. These data indicate a cross-reactivity of idiotypic determinants between human rye I-specific IgG and mouse monoclonal antibodies, which implies structural similarity in the V gene coding for the variable region of the antibody.