Allotype suppression in rabbits: the requirement for CH3 domain of anti-allotype antibody.

Facb fragments of rabbit anti-allotype antibody were prepared by plasmin digestion and isolated by gel chromatography. The antibody preparation was used in an attempt to induce allotype suppression in newborn rabbits. The Facb fragments were found to be ineffective in inducing the allotype suppression. Administration of Facb fragments caused a "burst" of immunoglobulin synthesis almost immediately after the administration of the antibody. It was concluded that the CH3 domain, which is responsible for the cytophilic activity of the antibody, is essential in induction of allotype suppression.