Genetic and biological characterization of a T suppressor cell induced by anti-idiotypic antibody.

The cellular and molecular characteristics of anti-idiotype-induced suppression have been investigated. We have shown that i.v. immunization of A/J or C.AL-20 mice with rabbit antibodies against the major cross-reactive idiotype on A/J anti-ABA antibodies induces splenic suppressor T cells (Ts) able to suppress T cell-mediated cytolytic and delayed-type hypersensitivity responses to ABA. In these studies, we compare the T suppressor activity manifested by anti-Id-induced suppressor cells with that described previously after conventional antigen priming. Results indicate that i.v. injection of anti-idiotypic antibodies primes for efferent level Ts; in contrast, i.v. administration of ABA-coupled cells induces afferent level suppressor cells. Soluble cell lysates, containing suppressor factor(s) derived from these anti-idiotype-induced Ts, can also mediate suppression of T cell immune responses in an efferent manner. Factor-mediated suppression is MHC-unrestricted and is also observed in mice pretreated with cyclophosphamide, suggesting that this activity is analogous to third-order suppression. Furthermore, this factor suppresses the T cell-mediated DTH and CTL responses in an antigen-nonspecific but Igh-restricted manner. These latter results suggest that the cellular elements conferring antigen specificity and Igh restriction are separate. The implications of these findings to the relationship between idiotypic elements, antigen-binding structures, and Igh restriction elements on immunoregulatory T cells are discussed.