An interspecies idiotope associated with the anti-cholera toxin response detected by a monoclonal auto-anti-idiotypic antibody.

We have produced an auto-anti-idiotypic (auto-anti-id) monoclonal antibody (mAb) which reacted with syngenic mouse polyclonal anti-cholera toxin (anti-CT) IgG antibody (Ab) and six/eight different anti-CT IgG mAb, but not with normal mouse BALB/c IgG. The binding of this auto-anti-id mAb on one anti-CT mAb was significantly inhibited by polyclonal anti-CT sera of rats, rabbits and mice. Thus the idiotope on anti-CT Ab recognized by this auto-anti-id mAb was public and expressed in different species. Because of the absence of competition between CT and this auto-anti-id mAb for the binding to the six anti-CT mAb, the anti-id mAb was classified as an Ab2 alpha. The efficiency of this auto-anti-id mAb to induce anti-CT Ab3 was tested with success in rabbits and rats. Auto-anti-id mAb-immunized rats were significantly protected against an intraintestinal CT challenge.