Induction of specific immune unresponsiveness with purified mixed leukocyte culture-activated T lymphoblasts as autoimmunogen. III. Proof for the existence of autoanti-idiotypic killer T cells and transfer of suppression to normal syngeneic recipients by T or B lymphocytes.

Specific immune unresponsiveness against a given set of histocompatibility antigens can be induced by immunization with autologous, antigen-specific T lymphoblasts. Such unresponsiveness can be transferred by lymphoid cells from autoblast-immunized donors to normal syngeneic recipients. The cells being most efficient in transferring the selective suppression are T lymphocytes from the spleen, especially if of Ly 1-2+3+ phenotype. By using such T lymphocytes we deem it likely that the actual underlying mechanism is one of actual transfer of autoanti-idiotypic killer T cells. In support for this view is the fact that such T cells endowed with exquisite specific, cytolytic reactivity towards autologous idiotype-positive T target cells exist in autoblast immune animals. Significant suppression may also be transferred with T cells of Ly 1+2-3- phenotype or with B cells. Here, we consider the suppressive mechanism to be one of production of autoanti-idiotypic antibodies. By using affinity fraction procedures, it was finally possible to prove that all T-cell suppressive activity resides in a population with true antigen-binding-specific receptors for the relevant idiotypes.