Idiotypic specificities and cross-reactivities of rabbit antibodies to human antidextran

Idiotypic antibodies were prepared by immunizing two groups of rabbits with dextran-antidextran specific precipitates and purified antidextran obtained subsequently from the same human donor. Half of the animals were made tolerant to pooled human IgG. Tests showed that sera from tolerant rabbits reacted better with the antidextran preparation used to immunize the other group of animals than with the antidextran that formed part of their immunogen. Non-tolerant animals did not recognize this serological difference. Sera from animals immunized with the antidextran preparation donated later reacted better with this material irrespective of their tolerance to human IgG.