The immune response against anti-idiotope antibodies. I. Induction of idiotope-bearing antibodies and analysis of the idiotope repertoire

Enhanced antibody responses to an HIV-1 membrane-proximal external region antigen in mice reconstituted with cultured lymphocytes

We have shown that the protective HIV-1 Ab, 2F5, avidly reacts with a conserved mammalian self-Ag, kynureninase, and that the development of B cells specific for the 2F5 epitope is constrained by immunological tolerance. These observations suggest that the capacity to mount Ab responses to the 2F5 epitope is mitigated by tolerance, but such capacity may be latent in the pretolerance and/or anergic B cell pools. In this study, we use B cell tetramer reagents to track the frequencies of B cells that recognize the HIV-1 2F5 epitope (SP62): in C57BL/6 mice, SP62-binding transitional B cells are readily identified in bone marrow but are lost during subsequent development. Unsurprisingly then, immunization with SP62 immunogen does not elicit significant humoral responses in normal C57BL/6 mice. Reconstitution of Rag1(null) mice with normal congenic B cells that have matured in vitro restores the capacity to mount significant serum Ab and germinal center responses to this HIV-1 epitope. These B cell cultures are permissive for the development of autoreactive B cells and support the development of SP62-specific B cell compartments normally lost in 2F5 Ab knockin mice. The recovery of humoral responses to the 2F5/SP62 epitope of HIV-1 by reconstitution with B cells containing forbidden, autoreactive clones provides direct evidence that normal C57BL/6 mice latently possess the capacity to generate humoral responses to a conserved, neutralizing HIV-1 epitope.

Anti-anti-idiotypic (Ab3) antibodies that bind progesterone-11alpha-bovine serum albumin differ in their combining sites from antibodies raised directly against the antigen

Polyclonal rabbit anti-idiotypic (Ab2) antibodies raised against the antiprogesterone mAb DB3 (Ab1) were used to induce an Ab3 antiprogesterone response in BALB/c mice. While the affinity of Ab3 sera for progesterone was 10-50-times lower than that of DB3, their steroid-binding specificity showed considerable similarity to DB3. Two immunoglobulin M (IgM) Ab3 monoclonal antibodies (mAbs), 1A4 and 3B11, were obtained, both of which bound progesterone conjugated to bovine serum albumin (progesterone-BSA). 1A4 also bound free progesterone, although with low affinity and very broad cross-reactivity. Like DB3, 1A4 is encoded by a heavy-chain variable region (VH) gene segment from the small VGAM3.8 family, a restriction that is characteristic of antibodies raised against progesterone-11alpha-BSA. In contrast, 3B11 binds progesterone-11alpha-BSA but not free progesterone and is encoded by an unrelated VH gene from the J558 family. The light chain variable region (VL) of 1A4 lacks the intradomain disulphide bridge owing to replacement of CysL23 by Tyr. Both the 1A4 and 3B11 heavy chains have extremely short complementarity determining region (CDR) H3 loops, comprising three and four amino acids, respectively. Modelling of the combining site of 1A4 from the X-ray crystallographic structure of DB3 indicates that the short H3 loop is a major factor in the loss of affinity and specificity for steroid.

Transient dominance of the early primary immune response by a highly conserved B-cell clone that is distinguished by its lack of memory, high threshold of activation, and a high affinity

We establish here that the very early primary response to the hapten phthalate (Xmp) is distinguished by a restricted heterogeneity with over 80% of the anti-Xmp antibodies expressing a single well-defined cross-reactive idiotype (CRIXmp-1) associated with a previously described highly conserved clonotype that is expressed by most inbred strains of mice and many outbred mouse populations as well. The characteristic early dominance of this one clonotype in the primary response is transient. While the CRIXmp-1 clonotype is present later in the primary and throughout the secondary response, it represents only a very small proportion of the total anti-Xmp antibody population at these times. The early dominance of the single clonotype is rapidly replaced by a heterogeneous population of antibodies. Differential activation thresholds for the primary response clonotype (CRIXmp-1) and secondary response clonotypes, and the failure of the dominant primary response clonotype to expand in the secondary response (i.e., absence of memory) suggest the presence of two distinct B-cell lineages.

Investigation of the poultry idiotypic network using Pasteurella multocida

The idiotypic network in leghorn laying hens was investigated by inoculating hens with a 35.5 kD outer membrane protein of Pasteurella multocida (Pm35.5), idiotype (Id), or Pm35.5 anti-Id. Egg yolks were analyzed for the presence of Id, anti-Id, or anti-anti-Id. Anti-Pm35.5 antibodies (Id) were not titered to an end-point but were present in high concentrations. The presence of anti-Id antibody in yolk was demonstrated by the inhibition of Pm35.5 binding to Id by anti-Id using a flow microsphere inhibition immunoassay. Inhibition of Pm35.5 binding to Id caused by different anti-Id preparations ranges from 51.5 to 56.1%. Not all of the anti-Id bound to a paratope-associated Id, since 8.3-12.8% of the fluoresceinated anti-Id bound to Id-coated beads in the presence of excess Pm35.5. We confirmed that a portion of the anti-Id antibodies was an internal image of the Pm35.5 Id and could mimic antigen by demonstrating that anti-Id inoculated in naive hens caused the synthesis of anti-anti-Id antibodies that bound to Pm35.5 in enzyme linked immunosorbent assay. Monoclonal anti-Id antibodies were also capable of inhibiting Pm35.5 binding to Pm35.5 Id coated microspheres and inducing anti-anti-Id antibodies in BALB/cJ mice that reacted with the original antigen, Pm35.5. Our investigation has also shown that idiotypic antibodies to P. multocida were transferred from chicken to egg.

Anti-ligand antibodies as potential autoantigens: in vitro and in vivo characteristics of anti-bungarotoxin antibodies in the idiotype network

Some antibodies to ligands of a receptor will have combining sites that structurally resemble the receptor's binding site for that ligand. The network hypothesis predicts that anti-idiotypic antibodies to these anti-ligand antibodies will also bind to the receptor. We pursued these hypotheses in the well-defined ligand-receptor system, alpha-bungarotoxin(BTX)-acetylcholine receptor (AChR). Monoclonal antibodies (mAbs) to BTX were generated; native BTX was used as the immunogen to optimize the probability of obtaining mAbs to the AChR binding site. These mAbs were then characterized for their ability to "mimic" AChR in the following in vitro assays: neutralization of BTX binding to native AChR on the surface of the cell line TE671, formation of a ternary complex with 125BTX-AChR, and ability of cholinergic ligands to interfere with binding to BTX. Three aBTX mAbs which had in vitro attributes of the AChR on the basis of these assays, were injected into C3H mice and serial sera tested for antibodies to Torpedo and murine AChR. Anti-AChR antibodies directed primarily to the gamma and delta subunits of the Torpedo AChR were detected, as well as low amounts of anti-mouse AChR antibody. The generation of anti-AChR antibodies by immunization with aBTX antibodies supports the network hypothesis and provides a theoretical basis for initiation of autoimmunity to cell receptors.

Characterization of the antibody response against the type II collagen induced by anti-idiotypic antibody

We reported that rabbit anti-idiotypic antibody (Ab2) against mAb, termed 1-5 (Ab1) and reactive with human type II collagen (CII) induced antibody response to CII in DBA/1J mice susceptible to collagen-induced arthritis. In the present study, we further characterized the anti-CII antibody response elicited by Ab2 with respect to epitope specificity, putative genetic background, and IgG subclass. Most of anti-CII antibodies (polyclonal Ab3) derived from Ab2-immunized mice were of the IgG1 subclass. We purified polyclonal Ab3, using a CII-coupled immunoadsorbent column and we developed monoclonal Ab3 from Ab2-immunized mice. Both purified polyclonal Ab3 and two monoclonal Ab3s specifically reacted with a selected epitope on CII, recognized by Ab1. The anti-CII antibody response stimulated by Ab2 was observed in DBA/1J (H-2q, Igh-1c) and DBA/2 (H-2q, Igh-1c) mice, but not in the BALB/c (H-2d, Igh-1a) and C57BL/6 (H-2b, Igh-1b) strains, thereby suggesting that the anti-CII antibody response elicited by Ab2 is controlled by the Igh gene.

The immune response to bacterial dextrans. VI. No correlation between the frequency of cells expressing a major anti-dextran idiotype and the idiotype profiles of specific antibody responses

C57BL/6 mice respond to Dextran B512 (Dex) with a predominant idiotype (Id) (17-9) while no such Id-positive antibodies are identified in the specific antibody response of BALB/c mice. We used limiting dilution systems to determine the absolute frequencies of clonal B-cell precursors producing the 17-9 Id in these two mouse strains and analysed the correlation between Id-expression and antibody activity at the clonal level. The results show very similar frequencies of anti-Dex and Id-positive B cells in both strains, but C57BL/6 mice contained fourfold higher frequencies of Dex-specific clonal precursors which are Id-positive. This kind of clone, although not used in the specific response of BALB/c mice, constitute roughly 20% of their anti-Dex repertoire and they are readily induced in this strain. Thus, immunization of both strains with anti-idiotypic antibodies results in the production of Id-positive anti-Dex antibodies with serum titres that directly correlate with precursor frequencies. The results show, therefore, that the section of clonal repertoires utilized in a primary immune response varies with the immunogen, even if thymus-independent. These observations are discussed in the context of the genetic controls of anti-Dex antibody responses and on the general question of the utilization of available antibody repertoires in immune responses.

Genetics of the induction of antigen-specific immunity in anti-idiotype-treated mice and derivation of monoclonal Ab3 antibodies

Antiidiotypic antibodies can be used as a means other than antigen of clone-specific intervention in the immune system. In a number of cases, antiidiotypic antibodies induce potent, antigen-specific responses without exposure of the recipient animals to antigen, and a better understanding of such responses will aid in the application of idiotype manipulation to both immunological and practical problems. The Ia. 7 system expresses a major, cross-reactive idiotype on antibodies to an epitope of the mouse I-E antigen. Here, we examine genetic control of the I-E-specific response to anti-idiotype in this model system. Results demonstrate that both heavy chain allotype-linked and non-allotype-linked loci contribute to the control of this response. In addition, monoclonal antibodies representing the non-antigen-specific portion of the Ab3 response were derived. Two idiotype-positive clones were demonstrated to be of IgM isotype, contrasting with previous data showing that the serum Ab3 response is predominantly IgG1.

Regulatory influences of neonatal multispecific antibodies on the developing B cell repertoire

In these studies we have emphasized the apparent developmental hierarchy of B cell development and assigned a role for the multispecific self idiotype reactive B cells which develop first, in promoting the development of later appearing clones of B cells. These early sets of interconnecting clones of B cells bridge between clones of cells involved in such disparate responses as anti-PC and anti-DEX. Interference with these idiotype directed interactions results in deficiencies in the adult B cell repertoire with respect to these responses. These idiotype directed interactions appear to be bidirectional in that interference with either antigen, Ab1, Ab2, Ab3, and Ab4 during neonatal life all produce striking effects on the adult responses to these antigens. These results strongly suggest that early idiotype directed interactions between B cells are essential for the establishment of the adult B cell repertoire.

A monoclonal anti-idiotypic antibody which mimics angiotensin II in inducing a population of anti-hormone antibodies

IG12, a syngeneic monoclonal anti-idiotypic antibody, was raised against an idiotype on a monoclonal antibody, ICH2, with specificity for the octapeptide hormone angiotensin II (AII). Competitive radioimmunoassays, and ELISAs utilizing AII antiserum raised in different species (rats and rabbits), indicate that IG12 detects a private idiotypic determinant at or near the paratopic region of the ICH2 combining site. Immunization of syngeneic mice with either IG12 or IG12 coupled to keyhole limpet hemocyanin induced a population of anti-anti-idiotypic antibodies that shared two properties with ICH2: the binding of AII and the binding to IG12. Antibodies from these anti-anti-idiotypic populations were also partially active in inhibiting the interaction between AII and ICH2. To our knowledge, this is the first demonstration of a monoclonal anti-idiotypic antibody mimicking a physiological hormone in inducing a population of anti-hormone antibodies.

In vivo generation and function of B cells in the presence of a monoclonal anti-IgM antibody: implications for B cell tolerance

C57BL/6 mice were chronically treated with milligram doses of the noncytotoxic monoclonal anti-mu b antibody MB86 (IgG1, kappa) from birth or from fetal life. The spleens of the manipulated animals contained large numbers (25% as compared to control mice) of B lineage cells which expressed IgMb on the surface after overnight incubation in vitro. The spleens also contained B cells whose surface IgM was unreactive with antibody MB86. A few such cells were immortalized by cell fusion. They included cells secreting mu together with lambda 2 chains which apparently prevent recognition by antibody MB86, and a point mutant in the first constant domain of the mu chain, changing the b to the a allotype. Cells expressing MB86- surface IgM did not selectively expand under MB86 treatment over the first few months of life. Serum Ig levels in the manipulated mice were normal except for IgM which was undetectable in most instances. In some animals low levels of MB86- IgM molecules were produced. At 7 weeks of age, mice treated with MB86 from birth produced normal-size IgG anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) responses with the usual predominance of lambda 1 chain-bearing IgG1 antibodies. At the age of 5-6 months, and also in young mice treated with MB86 from fetal life, the responses were variable and presumably oligoclonal, with a tendency towards the production of antibodies with gamma 3 heavy and lambda 2 or lambda 3 light chains. We interpret these results to mean that B cells hit by antibody MB86 from the time of their generation become unresponsive to T cell-dependent stimulation, but are still able to expand. Occasionally, they escape functional suppression through class switching (to IgG3) upon mitogenic stimulation. At birth, C57BL/6 mice contain a mature B cell population which mediates normal immune responses under MB86 treatment and eventually dies out. Taken as a model of tolerance induction in B cells, the data provide evidence for "tolerant" cells and support the concept of an early phase of sensitivity to tolerance induction in B cell differentiation. The anti-NP response under MB86 treatment differed profoundly from control responses in idiotypic terms, but became normal as the animals recovered from suppression. This may reflect blockade by MB86 of idiotypic selection within the B cell population.

Topographic analysis with monoclonal anti-idiotopes: probing the functional anatomy of immunoglobulin variable domains

Attempts to correlate immunoglobulin variable domain functional properties with variable domain primary structure have been valuable, but these efforts have suggested that to more fully account for variable domain function in terms of structure will require knowledge of molecular relationships in three dimensions. In this review we describe generally applicable methods, using monoclonal anti-idiotopes, for the determination of spatial relationships of idiotopes relative to one another and relative to two orienting structural markers of variable domains: 1) the hapten-binding site and 2) the junction of the variable and constant domains. Using these methods it has been possible to construct an oriented idiotope map which spans the variable domain along an axis connecting the paratope and the variable domain-constant domain junction. In addition, it has been possible to correlate idiotope position with other properties of idiotope expression. This approach may contribute to the development of predictive principles of idiotope expression.

Expansion and functional activity of Ly-1+ B cells upon transfer of peritoneal cells into allotype-congenic, newborn mice

Transfer of peritoneal cells from adult donors into newborn, allotype-congenic mice led to colonization of the recipient mice by donor-derived B lymphocytes expressing the Ly-1 surface marker (Ly-1 B cells). These cells not only persisted in the recipient mice for at least 5 months, but also increased in number. In contrast, bone marrow-derived stem cells did not or scarcely give rise to B cells after intraperitoneal injection into congenic newborn recipients under the same experimental conditions. Approximately half of the IgM in the serum of peritoneal cell-recipients was produced by donor-derived Ly-1 B cells, suggesting that high levels of serum IgM in a normal mouse are produced by this B cell subpopulation. The transferred Ly-1 B cells were able to respond in a normal fashion to alpha (1----3)dextran, but they did not participate in thymus-dependent and -independent (TI II) immune responses to the hapten (4-hydroxy-3-nitrophenyl)acetyl (NP). In neither the immune response to alpha (1----3)dextran nor that to NP were we able to detect an influence of the transferred Ly-1 B cells on the selection of the idiotypic repertoire in the recipient mice.

Analysis of somatic mutation and class switching in naive and memory B cells generating adoptive primary and secondary responses

Clonal progeny of naive B cells (producing a primary antibody response) and of memory B cells (producing a secondary response) were identified in a cell transfer system. Primary response clones are typically derived from IgM precursors and express unmutated V regions. Multiple isotype switches occur in these clones. Secondary response clones derive from IgG1 precursors and express highly mutated V regions. Additional switches do not occur. With one exception, there was no evidence for somatic mutation during clonal expansion. The generation of mutated memory cells may thus represent a distinct differentiation pathway. Evidence is presented that, in this pathway, mutants that have lost antigen binding specificity but that remain available for stimulation by a different antigen arise upon antigenic stimulation.

Enhancement and suppression of an intrastrain cross-reactive idiotype

The effects of a copolymer of monoclonal anti-idiotype (7B7.10) with keyhole limpet haemocyanin (KLH), designated 7-K, on an ongoing immune response were investigated. It was found that the response could be diverted to the production of higher titres of anti-p-azobenzenearsonate (Ar) antibodies, of which nearly 100% carry an intrastrain cross-reactive idiotype (CRIA). The effect was observed only in mice that had received a pre-inoculation of KLH-Ar, or KLH plus bovine gamma globulin-Ar (BGG-Ar). The effect was also observed, however, when cross-linked 7B7.10 was mixed, rather than conjugated with KLH, suggesting that the role of KLH was to induce the production of a B-cell growth factor. Cross-linked 7B7.10 was not effective in the absence of KLH. A primary inoculation of 7-K together with KLH-Ar did not result in significant suppression or enhancement of CRIA. Also, pre-inoculation of 7-K alone did not suppress a subsequent idiotypic response to KLH-Ar, whereas monomeric anti-Id was suppressive. This supports a possible role for the unmodified Fc segment in the suppressive mechanism. In mice primed with KLH-Ar, before administration of 7-K, CRI+A molecules lacking anti-Ar activity were present in very low concentrations in the immune sera. Larger quantities of such molecules were present in the sera of mice that received 7-K alone. The methods described permit the reproducible production of large amounts of CRI+A anti-Ar antibodies.

Induction of chronic idiotype suppression by ligands binding to the variable (not the constant) region of the idiotypic target

It was previously shown that in C57BL/6 mice chronic suppression of an idiotypically defined subset of lambda 1 chain-bearing anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies is achieved by neonatal administration of allogeneic monoclonal anti-idiotope antibodies reactive with this subset, or by NP coupled to mouse immunoglobulin. The present data show that isologous monoclonal anti-idiotope antibodies have the same effect. In contrast, antibodies against constant region determinants of lambda 1, mu or delta immunoglobulin chains failed to induce chronic suppression of the same antibody subset. Furthermore, the effect of the anti-idiotope antibodies was neutralized by idiotypic antibodies of the IgG1 class, injected before or together with the anti-idiotype. These results suggest that the mere complexing of idiotypic molecules on the B cell surface or in the circulation is insufficient for the induction of chronic idiotype suppression. In the present system, induction appears to require the binding of a ligand to idiotype-bearing receptor V regions, expressed on the surface of B (or T?) cells.

The expression of a private idiotope requires pretreatment with noncomplementary anti-idiotypic antibodies

The levan-binding ABPC48 myeloma protein is characterized by 3 idiotopes, (Ids), defined by 3 syngeneic monoclonal anti-idiotypic antibodies (IDA 10, IDA 16 and IDA 17). When BALB/c mice are immunized with levan, they produce anti-levan antibodies, some of which carry the Id 10 and Id 16 but not the Id 17 determinants. In the present study, we attempted to induce the synthesis of Id 17 positive anti-levan molecules. We found that immunization with IDA 17 antibodies alone was ineffective in inducing an Id 17 positive anti-levan response. By contrast, successive immunizations with IDA 10, IDA 16 and IDA 17 antibodies resulted in the synthesis of Id 17 positive anti-levan immunoglobulins. The synthesis of these molecules was concommitant with the induction of Id 10 and Id 16 positive anti-levan antibodies. Thus our data suggest that the Id 17 determinant on anti-levan antibodies is coexpressed with Id 10 and Id 16, and that successive anti-idiotypic treatment may result in the selective expansion of rare ABPC48 cross-reactive idiotype B-cell clone precursors.

A high incidence of cross-reactive idiotypes among murine natural autoantibodies

Anti-idiotypic (anti-Id) antibodies were produced in rabbits against two natural monoclonal IgM autoantibodies (NmAb), D23 and E7, which exhibited a broad reactivity and were derived from fusions of spleen cells from adult unprimed BALB/c mice and nonsecreting myeloma cell lines. They were used to test the reactivities of 12 NmAb obtained from adult and newborn unprimed mice. Both anti-Id recognized cross-reactive idiotopes frequently shared by NmAb; 8 out of the 12 NmAb reacted with anti-IdD23, while 5 of them also reacted with anti-IdE7. All of the Id-bearing antibodies possessed widespread reactivity with structurally dissimilar self and nonself antigens. In most cases, their cross-reactive Id determinants seemed to be located outside of their antigen-binding sites. Furthermore, the presence in normal mouse sera of significant levels of D23 and E7 idiotopes correlated with the presence of natural antibody activity and was mainly associated with IgM and IgG2b fractions. Finally, D23 idiotope(s) were also found on induced murine anti-myosin antibodies. The high incidence of cross-reactive idiotopes found among NmAb produced by clones derived from different mice and their presence in normal BALB/c mouse serum Ig fractions suggest that families of germ-line genes may encode for at least a part of them.

Drastic change in idiotypic but not antigen-binding specificity of an antibody by a single amino-acid substitution

In proliferating B lymphocytes, somatic mutation of rearranged antibody variable (V)-region genes occurs at high frequency and may have a key role in the selection of these cells. It is of interest in this context to learn in which way single mutations can affect antigen binding and/or idiotypic specificity of an antibody. Previous investigations have analysed spontaneous mutants of myeloma and hybridoma cells in which the mutation affected the antigen-binding specificity of the antibody. Here we describe an antibody mutant that has fully retained antigen-binding specificity but has lost or drastically changed all V-region antigenic determinants (idiotopes) of the wild type as defined by monoclonal anti-idiotope antibodies. The mutant phenotype is generated by a glycine to arginine exchange in the middle of the diversity (D) element, at position 103 of the heavy chain.

Immune response against poly(Glu60,Ala30,Tyr10) (GAT): immunization with monoclonal anti-idiotypic antibodies leads to the predominant stimulation of idiotypically similar immunoglobulins with anti-GAT activity

Two monoclonal anti-idiotypic antibodies (HP-Id20 and HP-Id22) recognizing two different public idiotopes expressed in the anti-poly(Glu60,Ala30,Tyr10) (GAT) response were used to immunize BALB/c and C57BL/6 mice. From these animals hybridomas were isolated. From BALB/c and C57BL/6 mice eight and seven monoclonal antibodies were characterized, respectively. The reagents were classified according to the expression of the public idiotypic specificity p.GAT (recognized by a rabbit antiserum). The anti-GAT activity and the expression of the various idiotopes characterized on anti-GAT polyclonal and monoclonal antibodies were also studied. Most of the reagents are Ab1'-type of antibody resembling anti-GAT antibodies. One anti-anti-idiotypic monoclonal antibody (Ab3) was also isolated from BALB/c mice. This suggests that in this experimental model the repertoire induced after HP-Id immunization and antigen stimulation is comparable. The idiotypic analysis of a large number of anti-GAT and of Ab1' monoclonal antibodies suggests that only two public idiotopes are involved in the anti-GAT response.

Induction by monoclonal anti-idiotypic antibodies of an anti-poly(Glu60 Ala30 Tyr10) (GAT) immune response in GAT-responder and GAT-nonresponder mice

Two different monoclonal anti-idiotypic (Id) antibodies, HP-Id20 and HP-Id22, recognizing two discrete idiotopes characteristic of the anti-poly(Glu60 Ala30 Tyr10) (GAT) response were used to immunize BALB/c (GAT-responder) and DBA/1 (GAT-nonresponder) mice. The monoclonals were injected either copolymerized with keyhole limpet haemocyanin or polymerized with glutaraldehyde. The specific response was studied by two assays: (a) inhibition of binding of monoclonal anti-GAT antibody G5Bb2-2 to HP-Id20 and HP-Id22 and (b) GAT binding assays. In BALB/c GAT-responder mice, HP-Id20 and HP-Id22 immunization led to the preferential stimulation of immunoglobulin idiotypically related to anti-GAT antibodies (Ab1') and expressing anti-GAT activity. The results obtained with BALB/c nu/nu mice indicated that this response is T-cell-dependent. By means of the same experimental protocol GAT-nonresponder animals could be induced to produce anti-GAT antibodies after HP-Id immunization. This last result indicates that anti-Id immunization can bypass Ir gene control and does not preferentially stimulate the induction of GAT-specific T suppressor cells.

Immune response induced by a single or several syngeneic monoclonal antiABPC48 antiidiotypic antibodies: no predominant coexpression of ABPC48 idiotopes

BALB/c mice were immunized with monoclonal BALB/c antibodies IDA10, IDA16 and IDA17 raised against the BALB/c ABPC48 myeloma protein. Several procedures of immunization--copolymers with lipopolysaccharide or keyhole limpet hemocyanin, simultaneous or sequential injections of different IDAs--were performed in an attempt to orient the immune response towards the production of ABPC48-like idiotypes. We used a binding assay which identifies two idiotopes on the same molecule to measure the population of antibodies induced in these responses. The expression of ABPC48 cross-reactive idiotypes in immune sera was analyzed. The results show that, with all immunization protocols, immune responses to different monoclonal antiidiotypic antibodies are mostly independent of each other: the coexpression of ABPC48 idiotopes, either private or recurrent on the induced antibodies, is rarely found; it makes it difficult to discriminate by a serological approach between cross-reactive idiotypes and anti-antiidiotypic antibodies. We discuss the interest of combining molecular and serological approaches to identify these two populations of antibodies.

Molecular analysis of induced idiotypes associated with autoanti-thyroglobulin

Idiotype (Id) and autoanti-thyroglobulin were induced in different strains of mice by priming with anti-Id to monoclonal anti-thyroglobulins (D8 and G4) and challenged with a subimmunogenic dose of thyroglobulin (Tg). Both D8.Id and G4.Id were induced in CBA mice by priming with the appropriate anti-Id, but only priming with anti-D8.Id also induced an increase in anti-Tg. D8.Id was induced in other strains by the same schedule but it only appeared to be associated with anti-Tg in 129 and, to a lesser extent, BALB/c mice, both of which have the allotype Iga. The extent of the overlap between the D8 Id and the anti-Tg was estimated and shown to be greatest in the CBA strain from which the D8 clone was originally derived. Spectrotypic analysis of the induced Ids in CBA mice showed that some of the D8.Id, but none of the G4.Id, was identical to the original clonotype, implying that CBA mice normally have cells which can be induced to produce D8.Id-positive autoanti-Tg, which are normally weakly expressed or regulated. The observation that anti-D8.Id priming in some strains increased D8.Id-negative anti-Tg responses suggests that the D8.Id may also be associated with anti-Tg T-cells.

Induction of anti-tobacco mosaic virus antibodies in mice by rabbit antiidiotypic antibodies

Conventional rabbit antiidiotypic antibodies were raised against a private rabbit anti-tobacco mosaic virus (TMV) idiotype. These rabbit antiidiotypic antibodies were covalently coupled to lipopolysaccharide and then injected into BALB/c mice. As compared with controls, these mice, which have never seen the antigen, synthesized anti-TMV antibodies that are strongly idiotypically cross-reactive with the starting rabbit idiotype. Monoclonal anti-TMV antibodies were prepared from these mice. Furthermore, xenogeneic or syngeneic antiidiotypic antibodies, raised against these monoclonal anti-TMV antibodies, recognized specifically the rabbit idiotype. Rabbit antiidiotypic antibodies alone can induce the same effects, but the concentration of anti-TMV antibodies is lower.

Frequencies of phosphorylcholine-specific and T15-associated 10/13 idiotope-positive B cells within lipopolysaccharide-reactive B cells of adult BALB/c mice

The frequencies of lipopolysaccharide-reactive B lymphocytes in adult BALB/c spleen cells were determined by limiting dilution experiments to be between 1 in 50 and 1 in 100. Within this reactive population, the frequencies of B lymphocytes specific for phosphorylcholine (PC) and/or binding a TEPC 15-associated idiotope-specific monoclonal antibody (10/13) were found to be between 1 in 50 and 1 in 500. Binding of these antibodies to immobilized PC or to monoclonal idiotope-specific antibodies could be inhibited by soluble PC in a solid-phase radioimmunoassay. Around half the PC-specific B cell clones were found to also bind 10/13 idiotope-specific monoclonal antibody, while the rest were either PC specific, but idiotope-negative or idiotope-positive, and unable to bind immobilized PC.

Cellular expression of idiotopes defined by monoclonal antibodies

Monoclonal anti-idiotype (Id) antibodies with specificities for determinants related to the antigen-binding sites of 3 BALB/c myeloma proteins, MOPC-460, HOPC-8 and J558, were used to study Id expression on murine lymphocytes. The monoclonal antibodies were shown to react only with Id structures associated with immunoglobulin on B cells. None of these 3 Id nor a VH Id, detected by a monoclonal antibody made against HOPC-8 heavy chain, were found on T cells. These Id were detected on splenic B cells in neonatal mice; the frequencies in normal, nude and germ-free mice were similar: MOPC-460 Id+: 1.05 +/- 1.7/10(4) spleen cells, HOPC-8 Id+: 1.45 +/- 1.2/10(4) and J558: 0.35 +/- 0.6/10(4). Almost all Id+ cells bore surface IgM, a few expressed surface IgG. MOPC-460 Id+ IgG+ cells were mainly gamma 2a+ or gamma 2b+, whereas J558 and HOPC-8 Id+ IgG+ cells were gamma 3+.

Specificity, duration and mechanism of idiotype suppression induced by neonatal injection of monoclonal anti-idiotope antibodies into mice

Monoclonal antibodies detecting idiotopes on the germ line-encoded anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibody B1-8 were injected at various doses into newborn mice and the expression of B1-8 idiotopes was measured in anti-NP responses in later life. Suppression was long lasting, and a 100-fold increase in the dose of anti-idiotope delayed recovery from suppression by 5-6 weeks. Upon injection of a single anti-idiotope, suppression was observed for all B1-8 idiotopes to various degrees. Certain idiotopically defined antibody phenotypes were much more efficiently suppressed, and later recovered from suppression, than others. This specificity pattern was observed at the level of both B and T cells from the manipulated animals, as demonstrated in cell transfer experiments in which such cells were mixed with normal T and B cells. In these experiments, there was evidence for suppression mediated by regulatory T (and possibly also B) cells. Whereas the B cells from the manipulated animals were idiotypically unresponsive in a T cell-dependent adoptive primary response, the frequency of lipopolysaccharide-reactive B cells expressing the target idiotype was only slightly reduced in these animals as compared to control mice. Together with data on the elimination of anti-idiotope antibody from the neonatally injected animals these results are interpreted in the following way: idiotype suppression is induced through the reaction of anti-idiotope with idiotopes expressed on the surface of newly generated B cells, at microgram concentrations of anti-idiotope. When the concentration of anti-idiotope fall below that level, recovery from suppression sets in. Two types of suppression are induced. The first, namely, direct blockade of B cell maturation, is short-lived. The second involves the induction of regulatory cells, perhaps through idiotope-bearing antibody V regions complexed by anti-idiotope. This type of suppression is long-lived and its specificity depends upon the distribution of the target idiotope in the antibody repertoire and/or peculiarities of the T cell receptor repertoire. It impinges on the selection of the B cell repertoire in the animal as expressed in T cell-dependent (and possibly other) responses and is thus hardly seen at the level of lipopolysaccharide-reactive (immature) cells. Idiotype suppression by regulatory cells may be perpetuated by antigen interacting with idiotypic antibodies on the B cell surface and may therefore play a role in establishing tolerance not only for the expressed antibody repertoire, but for self antigens in general.

Enhancement of the immune response to hepatitis B surface antigen. In vivo administration of antiidiotype induces anti-HBs that expresses a similar idiotype

BALB/c mice receiving antiidiotype antibodies before the injection of hepatitis B surface antigen (HBsAg) generated an enhanced anti-HBs response. Mice given antiidiotype antibodies in a soluble form induced predominantly IgM anti-HBs, whereas alum-precipitated antiidiotype produced primarily IgG anti-HBs. Injection of antiidiotype antibodies alone induced anti-HBs that inhibited a common interspecies anti-HBs idiotype-antiidiotype reaction and recognized the group-specific determinant of HBsAg. These data support the view that antiidiotype antibodies may modulate the immune response to an infectious viral agent.

Idiotope regulation by isotype switch variants of two monoclonal antiidiotope antibodies

Previous work has shown that the injection of antiidiotope antibodies specific for idiotopes of the germline-encoded anti-(4-hydroxy-3-nitro-phenyl) acetyl (NP) antibody B1-8 enhanced or suppressed the expression of B1-8 idiotopes in subsequent humoral anti-NP responses, depending on the dose and perhaps also the isotype of the injected antibody. To formally answer the question of whether the isotype of an antiidiotope determines its effector function in this type of idiotypic control, we have performed regulatory experiments with isotype switch variants selected from two hybridomas secreting anti-B1-8 idiotopes of CBA (Ighj) and C57BL/6 (Ighb) origin. The antibodies of each variant family differ from each other only in the constant region of the heavy chain. The results show that, irrespective of whether an antiidiotope antibody belongs to the IgG1, IgG2b, IgG2a, or IgE class, a 10-ng dose enhances idiotope expression whereas a dose of 10 micrograms exerts a suppressive effect. It emerges from the present and parallel data that the expression of antibody V regions resembling idiotypically that of antibody B1-8 can be enhanced and suppressed by any of four antiidiotope antibodies that recognize distinct idiotopes on those V regions. This suggests that the initial step in the regulatory process induced by an antiidiotope is its binding to antibody V regions carrying the target idiotope. The antiidiotopes preferentially regulate the expression of antibodies that coexpress with the target idiotope other B1-8 idiotopes, despite the fact that some B1-8 idiotopes are also expressed independently of each other in anti-NP responses of idiotypically unmanipulated mice. This finding may reflect high affinity binding of the antiidiotopes to the target against which they were originally raised (i.e., antibody B1-8) or, more likely, a preferential recognition of B1-8-like V regions by regulatory T cells.

Non-dinitrophenyl-binding immunoglobulin that bears a dominant idiotype (Id460) associated with antidinitrophenyl antibody is specific for an antigen on Pasteurella pneumotropica

We have previously described an idiotype (Id460) that transiently dominates anti-2,4-dinitrophenyl (DNP) antibody responses of mice that possess the appropriate Igh-V and V kappa genotypes. Normal serum has significant levels of Id460 that does not bind DNP, and hybridomas derived from spleen cell fusions that produce monoclonal antibodies with these characteristics have been generated. Many of these monoclonal, Id460-positive antibodies bind the opportunistic mouse pathogen Pasteurella pneumotropica. P. pneumotropica induces a marked increase in serum Id460 titers without significantly increasing serum anti-DNP titers. Both normal serum and P. pneumotropica-induced Ig460-positive immunoglobulin specifically bind to P. pneumotropica. These results suggest that the normal serum Id460-positive immunoglobulin is induced by environmentally encountered antigens on P. pneumotropica. We propose that this naturally occurring Id460 activates antiidiotypic regulatory cells that in turn promote production of Id460-positive anti-DNP antibody following DNP-ovalbumin immunization. These data are compatible with those obtained in several other idiotypic systems that suggest that dominant idiotypes may be associated with antibodies that have been evolutionarily selected for expression because of their specificity for antigens on environmentally encountered pathogens.

Allotypic restriction of the expression of MOPC460 idiotope after immunization with either anti-2,4-dinitrophenyl (DNP) or anti-idiotypic antibodies

The MOPC460 idiotype is expressed in mice with the IghCa allotypic haplotype after anti-2,4-dinitrophenyl (DNP) immunization. We have previously shown that two monoclonal syngeneic anti-idiotypic antibodies (IDM 92-13 and IDM 41-27) define two distinct idiotopes (the 460.92 and the 460.41) on the M460 idiotype. The current study demonstrates that only one idiotope (460.92) is recurrently expressed after antigen immunization in IghCa positive mice and also that, immunization against the monoclonal anti-idiotypic molecules induces the synthesis of 460.92 idiotope positive anti-DNP antibodies. However, the detection of such molecules is only possible when animals with the IghCa allotypic haplotype are immunized with the IDM 92-13 molecules. Immunization of mice with either of the two monoclonal anti-idiotypic antibodies never results in the synthesis 460.41 positive molecules. Therefore, whatever protocol of immunization used, the expression of 460.92 was allotypic restricted.

Incomplete expression of the MOPC 460 idiotype in the sera of BALB/c mice immunized either with DNP antigen or with anti-idiotypic antibodies

The MOPC 460 idiotype, as defined by polyclonal probes, has been described as a recurrent marker among the anti-DNP antibodies synthetized by IghCa mice. In this paper, we demonstrate, using syngeneic monoclonal anti-idiotypic probes, that only a part of the idiotopes of this idiotype are indeed recurrently expressed in BALB/c mice (IghCa) after immunization with DNP antigen. We will also show that the immunization of BALB/c mice with monoclonal anti-idiotypic antibody specific for the recurrent determinant results firstly in the synthesis of anti-DNP antibodies and secondly in the expression of the same recurrent M460 idiotope present on a part of induced anti-DNP molecules. Contrary to this, the immunization with the monoclonal anti-idiotypic antibody specific for the private idiotope never resulted in the synthesis of anti-DNP antibodies. These results clearly suggest that, after DNP or anti-idiotypic immunization, the M460 idiotype is not expressed in its entirety.

The immune response against anti-idiotope antibodies II. The induction of antibodies bearing the target idiotope (Ab3 beta) depends on the frequency of the corresponding B cells

In the present study we use two monoclonal anti-idiotope antibodies (Ac38 and Ac146; Ab1) against the germ line-encoded, lambda 1 chain-bearing and (4-hydroxy-3-nitrophenyl)acetyl (NP)-binding antibody B1-8 (Ab1) for the induction of complementary antibodies (Ab3) and ask the question to what extent antibodies bearing B1-8-like idiotopes (Ab3 beta) are represented in the Ab3 population. In this experimental system, Ab3 beta is distinguished from the remaining Ab3 population (Ab3 alpha) by three properties which Ab3 beta may share with B1-8: (a) the binding of NP, (b) the binding to Ac146 (if induced by Ac38) or the binding to Ac38 (if induced by 146) and (c) that they carry lambda 1 chains. Antibodies with all three properties are induced in low amounts by both anti-idiotopes. Also, Ac146 induces only Ab3 alpha (bearing kappa chains and not binding NP and Ac38). In contrast, Ac38 triggers almost exclusively a lambda 1 chain-bearing response, i.e. Ab3 beta. The response has an unusually large size, reaches its maximum after a week and is long-lasting. An analysis at the level of lipopolysaccharide-reactive precursor B cells demonstrates that, in this case, cells expressing Ab3 beta occur at exceedingly high frequency (approximately equal to 10(-3] and are at least 10 times more frequent than cells expressing Ab3 alpha. The high frequency of Ab3 beta-expressing cells correlates with the contribution of several VH, D and J genes to the expression of this particular idiotope. In the case of the Ac146 anti-idiotope antibody, the response is dominated by Ab3 alpha. Ab3 beta represents less than 10% of the total response, reaches maximal levels 2 weeks after immunization and declines rapidly. This correlates with a low frequency of precursor B cells expressing Ab3 beta (approximately equal to 10(-5] and a restriction of the corresponding idiotope to rare VH-D combinations, caused presumably by a stringent contribution of the H chain to this idiotope which covers the NP-binding site. Our data suggest that anti-idiotypic antibodies (Ab2) against Ab1 will preferentially induce antibodies idiotypically related to Ab1 if the corresponding idiotopes are expressed in high frequency in the B cell compartment. This is expected in cases where Ab2 recognizes an idiotope that can be formed by many germ line-encoded VH-D-VL-combinations.

Antiidiotype stimulation of antigen-specific antigen-independent antibody responses in vitro. I. Evidence for stimulation of helper T lymphocyte function

Antibodies specific for the idiotypes of B10 anti-(T,G)-A-L antibodies (anti-Id) induced in vivo (T,G)-A-L-primed lymphocytes to secrete anti-(T,G)-A-L antibodies in vitro in the absence of antigen. Responses to anti-Id were quantitatively and qualitatively similar to responses to antigen. Responses were specific in that: (a) only lymphocytes primed in vivo with (T,G)-A-L (but not other antigens or unprimed cells) were inducible; (b) only anti-Id (but not a variety of control antibodies) induced responses; and (c) only anti-(T,G)-A-L antibodies were secreted. Antigen-primed T lymphocytes mixed with unprimed B plus accessory cells also responded to anti-Id and the phenotype of the responding T cells was Lyt-1+, Lyt-2-. Supernatants obtained from antigen-primed T cells incubated for 3 d with anti-Id (but not when incubated with controls) provided help to unprimed B plus accessory cells in the presence of anti-Id, thus providing direct evidence for induction of T lymphocyte helper function by anti-Id. In contrast to responses to (T,G)-A-L, responses to anti-Id did not appear to be regulated by H-2-linked Ir genes. The system described is a powerful tool for delineation of the mechanisms whereby antiidiotype antibodies affect lymphocyte function.

Symmetry and asymmetry in idiotypic interactions

At the level of antibody molecules, the partners in an idiotypic interaction are functionally equivalent, and the distinction between "idiotype" and "anti-idiotype" is merely operational. This point must be taken into account in the interpretation of regulatory experiments with "idiotypic" and "antiidiotypic" antibodies. Indeed, consistent interpretations of certain sets of data can be obtained if "idiotype" and "antiidiotype" are used as operational terms for functionally equivalent molecules with complementary binding sites. For interacting antibody populations, symmetrical and asymmetrical situations can occur. The latter case is when an antibody family whose members express a set of idiotypes in various combinations--a typical situation in germ-line encoded immune responses--interacts with a heterogenous population of anti-idiotypes, the common denominators of which are binding sites for the common idiotopes expressed in the idiotypic antibody family. Through this type of interaction, one can explain in a first approximation the experiments of Urbain, Cazenave and others in which antiidiotypic antibody populations (ab2) induce antibodies (ab3) which resemble the original idiotypic population (ab1) idiotypically, but not primarily in antigen-binding specificity. Such a model would also describe an idiotypic network in which germline-encoded recurrent idiotypes (expressed in antibody families of the type described above) interact with anti-idiotypes generated by somatic mutation.

Molecular basis of a mouse strain-specific anti-hapten response

The response of C57BL/6 and BALB/c mice to immunization with proteins coupled to (4-hydroxy-3-nitrophenyl)acetyl (NP) is dominated by distinctly different sets of antibodies. The VH gene family previously shown to be involved in the C57BL/6 response has now been shown to have highly homologous counterparts in BALB/c but of five sequenced BALB/c VH regions, none appeared likely to be able to encode an NP-binding protein. The active VH region from a BALB/c hybridoma making a characteristic anti-NP antibody was recovered and sequenced and shown to be quite different from the VH gene family involved in the C57BL/6 response. Comparison of the variation of the closely related VH regions between the two mouse strains showed that there are separate types of evolutionary pressures on the framework and complementarity-determining regions. The molecular basis for strain-specific immune responses appears to be that the structural divergence of VH regions between mouse strains is great enough that different strains use different VH regions for making the predominant class of antibodies to a specific hapten.

The expression of a set of antibody variable regions in lipopolysaccharide-reactive B cells at various stages of ontogeny and its control by anti-idiotypic antibody

An analysis is presented in which we measure the expression of a subset of antibody variable (V) regions in lipopolysaccharide (LPS)-reactive precursor B cells at various stages of ontogeny. The V regions were characterized by hapten (4-hydroxy-3-nitrophenyl)acetyl (NP)-binding specifity and/or expression of idiotypic determinants whose genetic basis had been explored in previous studies. Only V regions containing the V lambda 1 domain were considered: this allowed an unequivocal determination of idiotopes and reduced heterogeneity in the system essentially to the multiplicity of VH and D genes. It was found that approximately every fourth lambda 1-bearing LPS-reactive splenic B cell produces an NP-binding antibody. Approximately 1 in 40 lambda 1-bearing cells expressed an idiotope (Ac38) which is encoded by V lambda 1 and a set of related VH genes in combination with D and J elements. Of these cells, only a minority produce an NP-binding antibody and a few percent of the latter express a second idiotope (Ac146) which is known to be restricted to a subset of Ac38-positive, NP-binding humoral antibodies. All these frequencies are in good accord with previous analyses of anti-idiotope-induced antibodies in the serum. They can be easily accommodated into a simple model of random selection of VH genes in LPS-reactive B lymphocytes. The frequencies of the V regions under study were essentially the same in LPS-reactive B cells from spleens of adult and newborn animals and in LPS-reactive B cells generated from bone marrow pre-B cells in vitro. In the case of the latter cells the frequencies were independent of the absence or presence of T cells in the culture system. While we could thus detect, in naive mice, neither positive nor negative selection of the cells from the time of their generation in the bone marrow until their arrival in the periphery, negative selection is in principle possible: the presence of microgram amounts of anti-idiotope antibodies during maturation from pre-B to B cells specifically blocks the appearance of idiotope-bearing LPS-reactive cells in vitro. The potential physiological role of the latter effect in the sense of self-stabilization of the expressed antibody repertoire in ongoing immune responses and the possibility that frequency determinations in LPS-reactive B cells may be not representative for the repertoire expressed in the population of mature B cells is discussed.