Destruction of antibody idiotopes with ultra-low concentrations of reducing agents

The nature of the idiotopes present on F(ab')2 fragments prepared from rabbit anti-micrococcal carbohydrate antibodies and the loss of idiotypic reactivity of these F(ab')2 fragments upon iodination were examined. Rabbit anti-micrococcal idiotopes were shown to be exquisitely sensitive to treatment with very low concentrations of sodium metabisulfite or 2-mercaptoethanol. The treatment destroyed anti-micrococcal idiotopes, as shown by the loss of idiotopes on F(ab')2 fragments after reduction; the allotype epitopes and the antigen binding capacity of the F(ab')2 fragments were unaffected. The destruction of the idiotopes by very low concentrations of reducing agents indicated that an extremely labile disulfide bond is involved in the structure of the idiotope or in the maintenance of the conformation of the anti-micrococcal idiotopes. Identical reduction-sensitive anti-micrococcal idiotopes have been demonstrated in a number of related outbred rabbits, and in each case they induced a natural auto-anti-idiotype (AAI) antibody response. Recognition of the existence of these reduction-sensitive idiotopes and their properties could provide a basis for further study of these idiotopes and may lead to a better understanding of the idiotope network.