Induction of autoanti-idiotypic antibodies and effects on the subsequent immune response

Assessment of a functional role of auto-anti-idiotypes in idiotype dominance

We have used a well-defined idiotypic system, the cross-reactive idiotype of A strain (CRIA) (Ab1) idiotype generated in A/J mice injected with arsonate coupled to keyhole limpet hemocyanin (ARS-KLH), to determine the frequency of precursors for auto-anti-idiotypic antibodies (auto-Ab2) in naive and immunized A/J mice by limiting dilution analysis after polyclonal activation by lipopolysaccharide. In naive animals, the precursor frequencies of auto-Ab2 B cells were below the limit of sensitivity of the technique in the majority of A/J mice, and could be detected in only 20% of the animals. Upon immunization with ARS-KLH, a large increase in auto-Ab2 precursor frequency was observed. This shift in frequency was not found when A/J mice were injected with KLH alone, or when BALB/c mice, which do not express the CRIA idiotype, were injected with ARS-KLH. To study the functional role of the auto-Ab2 B cells, we injected neonatal A/J mice with polyclonal rabbit Ab3 antibodies directed against a recurrent idiotype of auto-Ab2. Thereafter, these mice were injected with ARS-KLH. Although the anti-arsonate response level was normal, the CRIA Ab1 expression was reduced tenfold. Thus, the suppression of auto-Ab2 affects Ab1 dominance. We further show that the presence of maternal Ab1 can strongly modify the immune response of the offspring by inducing higher levels of the idiotype after immunization. Furthermore, IgM anti-arsonate antibodies were detected before immunization with antigen. From these data, we conclude that the affinity of antigen alone cannot explain the dominance of CRIA. Network selection is important in the shaping of the available repertoire.

Idiotypic manipulations: hierarchy in idiotype expression in rabbits immunized against Micrococcus luteus

Idiotypic cross-reactions were analyzed among three series of anti-peptidoglycan antibodies of the Micrococcus luteus system. The reference idiotype Ab1 was an antibody fraction isolated from an isoelectric focusing preparative column. Cross-reactive idiotypes, Ab1', were induced through the immunization chain (Ab1-Ab2-Ab3). Idiotypic antibodies of Ab1-F1 type were obtained from offspring of female rabbits, actively producing Ab3 during pregnancy. Finally, Ab1 CRI were cross-reactive idiotypes with Ab1 found in a random population of rabbits immunized with M. luteus. Three idiotopes could be characterized within Ab1 antibody. Ab1' usually expressed two of these idiotopes, but never the third specificity which is "private" to Ab1. Ab1-F1 shared one or two idiotopes with Ab1 and Ab1' antibodies. Only one common idiotope appeared to be present on Ab1 CRI. Finally, this idiotope, IdX, could be detected by radioimmunoassay in 20% of rabbits immunized with micrococcal vaccine. It appears that a recurrent idiotype of anti-peptidoglycan antibodies can be preferentially amplified through idiotypic manipulations. On the other side, cascade immunizations lead to the expression on Ab1' and on some Ab1-F1 of a second idiotypic specificity, shared with Ab1. This hierarchy of idiotype expression may well be important in the regulation of antibody synthesis through idiotypes.

Human auto-antiidiotypes regulating T cell-mediated reactivity to tetanus toxoid

While investigating the effect on B cells of repetitive in vivo immunization with tetanus toxoid (TT), we observed the subsequent development of specific anergy for T cell delayed hypersensitivity (DTH) to TT. This appeared approximately 35 d after a series of five booster immunizations. Concurrently, in vitro T cell blastogenic responses were preserved. Serum obtained when the skin tests were nonreactive demonstrated a profound inhibitory activity on T cell reactivity. This activity was shown to be anti-antibody activity that was both anti-F(ab)'2 and, specifically, anti-TT F(ab)'2. It blocked binding of TT to a pool of allogeneic antibodies and also inhibited allogeneic antigen-specific T cell blastogenesis. Thus, we could identify activity in the serum of hyperimmunized individuals that appeared auto-anti-idiotypic (anti-id) and represented a single or family of major crossreacting idiotypes (id) for TT. The expression of the auto-anti-id correlated with the loss of T cell reactivity in vivo and in vitro. Subsequent examinations revealed persistent, specific cutaneous anergy beyond six months, which was then associated with a failure of T cells to react with antigen in vitro. Mixing experiments with cells from these later times and cryopreserved autologous cells obtained prior to hyperimmunization revealed there had been the development of antigen-specific T suppressor cells. Thus, in vivo DTH tolerance following hyperimmunization was associated with an inhibitory serum activity that appeared to be anti-id. Persistence of tolerance (greater than 6 mo) occurred with the development of T suppressor cells.

Study of the idiotypy of lipopolysaccharide-specific polyclonal and monoclonal antibodies

The monoclonal antibodies produced by a variety of hybridomas making antibody specific for E. coli 0113 lipopolysaccharide (LPS) were purified by affinity chromatography and their fine specificity studied. All reacted specifically with the polysaccharide moiety of LPS from E. coli 0113 and from Neisseria lactamica; two reacted with LPS from Pseudomonas aeruginosa and one reacted with LPS from Klebsiella pneumoniae. Polyclonal and monoclonal syngeneic and semi-syngeneic anti-idiotypic antisera were produced to study the idiotypy of LPS-specific monoclonal antibodies which express a complex cross-reactive idiotype (IdX) as well as individual idiotypes. E. coli 0113 LPS-specific antibodies produced by BALB/c mice express this IdX and the kinetics for its expression was examined using mice either primed or hyperimmunized with LPS; idiotypic maturation was observed, but we were unable to detect an auto-anti-idiotypic antibody response. This IdX was expressed on E. coli 0113 LPS-specific antibodies from all strains of mice examined, indicating that its expression is not restricted by genes linked to the IgCH locus.