Immune responses in breast cancer patients immunized with an anti-idiotype antibody mimicking NeuGc-containing gangliosides

A phase I clinical trial was conducted in patients with stage III/IV breast cancer who were treated with the anti-idiotype mAb 1E10 specific to an Ab1 mAb able to react specifically with N-glycolyl-containing gangliosides and with antigens expressed on human melanoma and breast carcinoma cells. Patients were treated with 1 or 2 mg of aluminum hydroxide-precipitated 1E10 mAb every other week for six injections. Two patients at each dose were reimmunized 7-9 months after completing the induction phase. In hyperimmune sera from eight of the nine patients who received at least four doses of anti-Id vaccine preparations, strong specific responses were observed both against 1E10 mAb and NeuGc-GM3 ganglioside (Ab3 Id+Ag+). Nonclassical Ab1' antibodies (Id-Ag+) were also elicited by 1E10 mAb vaccine treatment. There were no differences between the two levels of dose tested in relation to toxicity and immunogenicity. No evidence of serious or unexpected effects was observed.     

Genetic control of anti-idiotypic vaccination against coronavirus infection

The idiotypic network can be experimentally altered to induce protective immune responses against microbial pathogens. Both internal image and noninternal image anti-idiotypic (anti-Id) antibodies have been shown to trigger antigen (Ag)-specific immune responses. Therefore, mechanisms of anti-Id vaccination appear to go beyond structural mimicry of Ag, but remain undefined. Using the neurotropic murine coronavirus animal model, we have previously shown that a polyclonal noninternal image anti-Id (Ab2) could vaccinate BALB/c mice. To characterize its mode of action, we have examined the immune modulating capability of this Ab2 in vivo in strains of mice with different H-2 haplotypes. Even though only internal image anti-Id are expected to induce non-genetically restricted immunity, this noninternal image Ab2 induced protective immunity in four of eight genetically different strains of mice susceptible to coronavirus infection. These were BALB/c (H-2^d), DBA/1 (H-2^d), DBA/1 (H-2^q), and SWR (H-2^q) mice. Protection was generally correlated with the induction of specific antiviral Ab (Ab3) that showed biological properties, such as virus neutralization in vitro, similar to the initial Ab1. To evaluate the genetic implication of the H-2 haplotypes in protection, congenic mice were also tested. Vaccination profiles suggest that cooperation between background gene(s) of the BALB/c mouse with H-2^d and H-2^q loci is necessary for an optimal protective immune response, although the main genetic element(s) regulating the antiviral response to Ab2 inoculation appeared to be located outside the major histocompatibility complex. These results are consistent with the ability of Ab2 to induce protective antiviral antibodies in genetically different animals by biological mimicry.     

Characterization of protection against coronavirus infection by noninternal image antiidiotypic antibody

Previously, we have reported protective vaccination of mice against a coronavirus infection using rabbit polyclonal noninternal image Ab2gamma anti-idiotypic (anti-Id) antibody specific for a virus-neutralizing and protective monoclonal antibody (mAb) 7-10A against the viral surface S glycoprotein. To characterize further the mechanisms involved in the induction of protective immunity by this noninternal image anti-Id, plasma and splenocytes from Ab2gamma-immunized BALB/c mice were passively transferred to naive BALB/c mice, followed by viral challenge. A reproducible significant delay in mortality observed in mice to which plasma was passively transferred, together with the presence of specific in vitro neutralizing antiviral Ab3 identified the humoral immune response as the major element responsible for protection. The activation of specific and cross-reactive T lymphocytes by both virus and anti-Id in immunized mice and the absence of adoptive transfer of protection by splenocytes suggested the participation of T helper activity in the induction of protective virus-neutralizing Ab3. To obtain more defined monoclonal reagents for a better understanding of anti-Id-induced protection, mAb2 were generated against the same mAb1 7-10A and characterized. We report the successful generation of mAb2 of the gamma type. However, unlike the polyclonal Ab2gamma, they were not capable of inducing a protective immune response.     

Anti-idiotypic antibodies to feline leukemia virus: an approach for retroviral immunization strategies.

The present study describes an approach to the development and use of anti-idiotypic antibodies as a possible immunization strategy to prevent retroviral infection. The rationale for using anti-idiotypes (anti-Ids) to try to elicit an antigenic-specific immune response is examined, and the production and characterization of polyclonal and monoclonal anti-Ids are described. Several techniques were used to determine antigenic mimicry and anti-Id subtypes. The potential use of anti-Ids in feline leukemia virus (FeLV) receptor studies and vaccine trials in vivo were investigated. Results from these studies suggest that the anti-Id strategy is feasible for the FeLV model. Polyclonal Ab2 reagents were developed that blocked virus-receptor binding and thus inhibited viral infection in vitro and induced humoral immune responses in 6- to 8-week old kittens characterized by production of Ab3 with the ability to bind the original FeLV envelope protein gp70 as assessed by Western blot analysis.     

Insight into the potential for DNA idiotypic fusion vaccines designed for patients by analysing xenogeneic anti-idiotypic antibody responses

DNA vaccines induce immune responses against encoded proteins, and have clear potential for cancer vaccines. For B-cell tumours, idiotypic (Id) immunoglobulin encoded by the variable region genes provides a target antigen. When assembled as single chain Fv (scFv), and fused to an immunoenhancing sequence from tetanus toxin (TT), DNA fusion vaccines induce anti-Id antibodies. In lymphoma models, these antibodies have a critical role in mediating protection. For application to patients with lymphoma, two questions arise: first, whether pre-existing antibody against TT affects induction of anti-scFv antibodies; second, whether individual human scFv fusion sequences are able to fold consistently to generate antibodies able to recognize private conformational Id determinants expressed by tumour cells. Using xenogeneic vaccination with scFv sequences from four patients, we have shown that pre-existing anti-TT immunity slows, but does not prevent, anti-Id antibody responses. To determine folding, we have monitored the ability of nine DNAscFv-FrC patients' vaccines to induce xenogeneic anti-Id antibodies. Antibodies were induced in all cases, and were strikingly specific for each patient's immunoglobulin with little cross-reactivity between patients, even when similar VH or VL genes were involved. Blocking experiments with human serum confirmed reactivity against private determinants in 26-97% of total antibody. Both immunoglobulin G1 (IgG1) and IgG2a subclasses were present at 1.3 : 1-15 : 1 consistent with a T helper 2-dominated response. Xenogeneic vaccination provides a simple route for testing individual patients' DNAscFv-FrC fusion vaccines, and offers a strategy for production of anti-Id antibodies. The findings underpin the approach of DNA idiotypic fusion vaccination for patients with B-cell tumours.     

ABO-blood-group-related idiotypic network: mimicry of oligosaccharide epitope by rabbit antiidiotypic antibodies to murine monoclonal anti-A antibody.

The idiotypy of antibodies (Ab) specific for oligosaccharide determinants of blood groups of the human ABO system was studied through a cascade. Xenogenic antiidiotypic Ab (Ab2) raised in rabbits to the murine monoclonal anti-A61 (Ab1) were screened for reactivity with various anti-ABH Ab. Three anti-A and three anti-A,B monoclonal antibodies (mAb) which were developed in the same mouse strain as that producing Ab1, as well as a human polyclonal anti-A, were found to share cross-reactive idiotopes (CRI) with Ab1. CRI on murine mAb could be due to a Biozzi recurrent Id on anti-A Ab reacting with anti-Id "à la Oudin", while CRI on human anti-A Ab suggested the presence of paratope-induced anti-Id. Inhibition by Ab2 of haemagglutination of A, B or O human red blood cells by many murine anti-ABH mAb, and by polyclonal or monoclonal human anti-A, strongly supported the occurrence of anti-Id mimicking ABH epitopes belonging to type 2 determinants carried by human erythrocytes. Furthermore, a rabbit immunized with Ab2 produced a potent Ab3 response characterized by anti-H-type-2 specificity. Altogether, these results are consistent with the first successful production of anti-Id Ab that mimics the tridimensional shape of a well defined and strictly carbohydrate epitope, eliciting a haemagglutinating Ab3.     

ABO-blood-group-related idiotypic network: Mimicry of oligosaccharide epitope by rabbit antiidiotypic antibodies to murine monoclonal anti-A antibody

The idiotypy of antibodies (Ab) specific for oligosaccharide determinants of blood groups of the human ABO system was studied through a cascade. Xenogenic antiidiotypic Ab (Ab2) raised in rabbits to the murine monoclonal anti-A61 (Ab1) were screened for reactivity with various anti-ABH Ab. Three anti-A and three anti-A,B monoclonal antibodies (mAb) which were developed in the same mouse strain as that producing Ab1, as well as a human polyclonal anti-A, were found to share cross-reactive idiotopes (CRI) with Ab1. CRI on murine mAb could be due to a Biozzi recurrent Id on anti-A Ab reacting with anti-Id “à la Oudin”, while CRI on human anti-A Ab suggested the presence of paratope-induced anti-Id. Inhibition by Ab2 of haemagglutination of A, B or O human red blood cells by many murine anti-ABH mAb, and by polyclonal or monoclonal human anti-A, strongly supported the occurence of anti-Id mimicking ABH epitopes belonging to type 2 determinants carried by human erythrocytes. Furthermore, a rabbit immunized with Ab2 produced a potent Ab3 response characterized by anti-H-type-2 specificity. Altogether, these results are consistent with the first successful production of anti-Id Ab that mimics the tridimensional shape of a well defined and strictly carbohydrate epitope, eliciting a haemagglutinating Ab3.     

Moloney leukemia virus-induced cell surface antigen mimicry by monoclonal antibodies

We have investigated antigen-independent modulation of immune responses by monoclonal antibodies directed against both viral and nonviral antigens. BALB/c mice were immunized with monoclonal IgM (i.e. Ab1) specific for either Moloney murine leukemia virus-induced cell surface antigen (MCSA) or the hapten 2,4-dinitrophenyl (DNP). Injection with either Ab1 activated a functional idiotypic (Id) network as evidenced by production of both anti-Id (Ab2) antibodies and anti-anti-Id (Ab3) antibodies. A subset of induced Ab3 (designated Ab1), exhibited specificity for antigen (virus or DNP). In mice immunized with anti-Id antibodies (Ab2), production of Ab3 and Ab1′ was also observed. In the MCSA system, antibody-induced Ab1′ responses were effective in protecting mice from tumor development upon subsequent challenge with live virus. Furthermore, antigen-independent modulation of immunity to both viral and nonviral antigens was found to be thymus-dependent. Similar findings in other viral systems suggest that antibody-induced activation of Id networks may prove a viable alternative vaccine strategy that can elicit antigen-specific responses, and in some cases protection, in the apparent absence of exposure to antigen.     

具有抗—HBs结合活性的单克隆抗—抗独特型抗体的制备和鉴定

B_3为我室建立的带有HBsAg表位内影像的单克隆抗独特型抗体(mAb_2)。本文采用脾脏内和尾静脉内注射途径,用B_3免疫BALB/c鼠,获得了具有抗-HBs结合活性的同系单克隆抗-抗独特型抗体(mAb_3)3B_8株。这一结论基于以下两点观察:(1)3B_8能与纯化的HBsAg结合。纯化的HBsAg或抗-HBs均能以剂量依赖形式抑制这一结合;(2)3B_8能以剂量依赖形式抑制抗-HBs与B_3的结合。小鼠在从未接触HBsAg的情况下,单独用B_3免疫,获得了具有抗-HBs结合活性的单克隆抗-抗独特型抗体3B_8,进一步证明我室过去建立的mAb_2B_3株,确实带有HBsAg表位内影像。     

A syngeneic idiotype is immunogenic when borne by IgM but tolerogenic when joined to IgG

Some syngeneic monoclonal antibodies (mAb) elicit immune responses like conventional T-dependent antigens. To find out whether the heavy chain class (isotype) plays a role for the immunogenicity of an idiotype (Id), we isolated rare subclones of an IgM mAb (termed Id3) in which the variable region of the heavy chain (V_H) is associated with a new constant region (C_H). The V_H-Id3 gene is a member of the murine 36–60 family and probably has three replacement mutations. The light chain V gene is germ-line Vλ2. IgM, IgG1, IgG2a and IgG2b variants of Id3 were purified from protein-free medium and injected without adjuvant into BALB/c mice. The parental 19S IgM mAb given subcutaneously (s.c.) elicited a vigorous humoral response against Id3; in comparison, monomeric 8S IgM was a much weaker immunogen. Unlike IgM, multiple challenges with the IgG switch variants failed to induce anti-Id3 Ab. IgG variants gained immunogenicity if they were purified from medium containing fetal calf serum, mixed with complete Freund's adjuvant or injected into mice primed with IgM-Id3. Pretreatment with 100 μg s.c. + 50 μg of the IgG2a variant extinguished the Ab response to parental IgM, but the response to adjuvant-free bovine serum albumin was intact. Therefore, the tolerance induced by the IgG2a switch variant is antigen-specific and not due to toxicity. Significant inhibition of the Ab response to parental IgM was observed after treatment with 4 μg of the IgG2a switch variant. Administration of the IgG1 and IgG2b switch variants also inhibited this response significantly. Thus, the outcome of an encounter with Id3 is strongly influenced by the C_H isotype to which the Id is joined. This suggests novel ways to minimize unwanted Ab responses against Id of human therapeutic mAb. In the context of the theory of Id networks, we suggest that dominant B cell clones can preempt anti-Id Ab responses against themselves by early switching from IgM to IgG secretion, before immunogenic IgM Ab have had time to activate anti-Id B cells.     

Study of idiotypes expressed by monoclonal antibodies to the 35 kD and 12 kD antigens of Mycobacterium leprae.

Rabbit antisera were raised against four monoclonal antibodies (MoAb) binding with the 35 kD protein and four MoAb binding with the 12 kD protein antigen of Mycobacterium leprae. Antisera showed idiotype (Id) specificity following cross-absorption with normal mouse globulin. One Id on a single MoAb and another Id shared between three MoAb were identified for each group. Functional studies were carried out with the Rb04 anti [anti-35 kD] specificity. The expression of this Id and paratope in antigen immunized mice was associated with Igh alleles. Inoculation of mice with anti-Id Rb04 induced an 'Ab3' serum response of corresponding Id specificity only when the anti-Id was given in emulsion with incomplete Freund's adjuvant (IFA). Conversely, prior injection of soluble anti-Id inhibited the subsequent Ab3 response to Rb04/IFA. Moreover, the suppressive effect of soluble anti-Id was abrogated by prior injection of 50 mg/kg cyclophosphamide. These results indicate that regulatory mechanisms similar to those involved in antigenic stimulation may explain the stimulatory or suppressive potency of anti-Id antibodies. Finally, the Ab3 responses to the two tested anti-Ids did not contain any antigen binding activity.     

Anti-idiotypic immune responses against adjuvant-free isologous IgM monoclonal antibodies and their augmentation by complex formation between IgM and albumin in bovine serum.

In previous studies we demonstrated that the hypermutated isologous myeloma protein MOPC 315 (isotype IgA; λ2) is recognized by T helper cells like an ordinary foreign protein antigen. To what extent can an immune system recognize and respond to V domains from the primary (pre-immune) repertoire? To study this question we made 21 BALB/c hybridoma anti-2, 4, 6 trinitrophenyl monoclonal antibodies (mAb) of IgM; λ isotype. All mAb purified from supernatants containing fetal bovine serum had formed spontaneous complexes with bovine serum albumin possibly by way of disulfide interchange. Twenty of twenty-one mAb from this source elicited IgG₁ anti-idiotypic (Id) Ab when given as a single adjuvant-free dose of 200 μg. For 12 of them even 10 μg was sufficient. This indicated that BSA augmented the anti-Id responses by a carrier effect. Three of the mAb were therefore purified from ascites fluid and from serum-free medium. Only one of them then induced humoral anti-Id responses in BALB/c mice when given as a single adjuvant-free dose of 100 μg. The other two became immunogenic when emulsified in Freund's complete adjuvant. The results indicate that some IgM mAb exist whose Id determinants alone can elicit substantial anti-Id responses because they are recognized like ordinary foreign protein antigens. Since albumin in fetal bovine serum forms complexes with IgM and greatly augments its immunogenicity, serum-free medium should be used for production of human or humanized therapeutic IgM mAb. A possible role for Id of IgM Ab as cardinal autoantigens is discussed.     

Protection Against a Syngeneic Mammary Adenocarcinoma by Administration of Idiotypic and Anti-Idiotypic Antibodies

A hybridoma secreting a monoclonal antibody (mAb) with specificity for tumor-associated cell surface antigens of a transplantable murine mammary adenocarcinoma (SMC-168) was prepared by fusion of syngeneic C3H/He spleen cells with SP2 myeloma cells. Mice which were pretreated with this mAb (C–73) were significantly resistant to the outgrowth of a tumorigenic dose of SMC-168 cells when compared to controls. The treated nice developed tumor-specific cell-mediated immunity, measured by leukocyte adherence inhibition (LAI), which was equal to that of mice immunized with live tumor cells. The IgG fraction from serum of mice receiving mAb C-73 contained antibodies which would bind to that mAb suggesting the presence of anti-idiotypic antibodies (anti-Id). This binding could be partially inhibited by a soluble l-butanol cell surface extract of SMC-168. Rabbits were immunized with mAb C-73 to produce a polyclonal anti-Id. The purified and absorbed IgG fraction of this serum would bind only to mAb C-73 and not to other mAbs of the same isotype or normal C3H/HeN IgG. Binding of the rabbit anti-Id to mAb C-73 could be partially inhibited by soluble tumor-associated antigen extracted from SMC-168. Mice immunized with this polyclonal anti-Id vaccine developed tumor-specific cell-mediated immunity and were significantly resistant to the outgrowth of a tumorigenic dose of SMC-168.     

Protection Against a Syngeneic Mammary Adenocarcinoma by Administration of Idiotypic and Anti-Idiotypic Antibodies

A hybridoma secreting a monoclonal antibody (mAb) with specificity for tumor-associated cell surface antigens of a transplantable murine mammary adenocarcinoma (SMC-168) was prepared by fusion of syngeneic C3H/He spleen cells with SP2 myeloma cells. Mice which were pretreated with this mAb (C-73) were significantly resistant to the outgrowth of a tumorigenic dose of SMC-168 cells when compared to controls. The treated nice developed tumor-specific cell-mediated immunity, measured by leukocyte adherence inhibition (LAI), which was equal to that of mice immunized with live tumor cells. The IgG fraction from serum of mice receiving mAb C-73 contained antibodies which would bind to that mAb suggesting the presence of anti-idiotypic antibodies (anti-Id). This binding could be partially inhibited by a soluble l-butanol cell surface extract of SMC-168. Rabbits were immunized with mAb C-73 to produce a polyclonal anti-Id. The purified and absorbed IgG fraction of this serum would bind only to mAb C-73 and not to other mAbs of the same isotype or normal C3H/HeN IgG. Binding of the rabbit anti-Id to mAb C-73 could be partially inhibited by soluble tumor-associated antigen extracted from SMC-168. Mice immunized with this polyclonal anti-Id vaccine developed tumor-specific cell-mediated immunity and were significantly resistant to the outgrowth of a tumorigenic dose of SMC-168.     

Immune response to bovine viral diarrhea virus induced by anti-idiotypic antibodies.

We have previously prepared rabbit anti-idiotypic antibodies (anti-Ids) against the neutralizing monoclonal antibodies (MAbs) specific for the gp53 of bovine viral diarrhea virus (BVDV). The anti-Ids, purified by sequential immunoaffinity chromatography, inhibited the immunizing MAb from binding to the original antigens and blocked BVDV infection of cell cultures. This study evaluated immune responses in mice to the purified anti-Id reagents. BVDV-specific neutralizing antibodies were induced by the anti-Ids. The antisera (Ab3) induced by the anti-Ids immunoprecipitated gp53 from BVDV-infected Madin-Darby bovine kidney (MDBK) cell lysates. However, lymphocyte-proliferative responses were specific only for the respective immunizing antigens. These results suggest that the anti-Ids may bear an internal image of the gp53 to stimulate production of antibody but not to stimulate a virus-specific cellular immune response in mice.     

小鼠抗—HBs的单克隆抗独特型抗体杂交瘤细胞系的建立及鉴定

用纯化的小鼠单克隆抗-HBs(Ab1)免疫同系BALB/c小鼠,取免疫小鼠脾细胞与Sp2/0骨髓细胞融合,获得两株(MA1、MA3)持续分泌抗-HBs的单克隆抗独特型抗体(抗-1d,Ab2)杂交瘤细胞系。对MA3做了较全面的鉴定。MA3的Ig类型为IgM,核型分析结果染色体数为106条。通过ELISA竞争抑制和中和抑制试验表明,MA3所分泌的Ab2既能被不同来源的抗-HBs所中和,又能被HBsAg所竞争,且都呈现剂量依赖关系。将纯化的MA3 IgM免疫同系小鼠,诱导出具有抗-HBs活性的抗-抗-独特型抗体(Ab3)。因此认为MA3所分泌单克隆抗体(McAb),可模似HBsAg,具有类似HBsAg的免疫原性,是一种带有HBsAg表位内影像的抗-HBs的单克隆抗-1d。     

Polyclonal anti-idiotypic antibodies exhibit antigenic mimicry of limited type 1 fimbrial proteins of Escherichia coli.

Polyclonal anti-idiotypic antibodies (anti-Ids)(fim) developed against idiotypes on antibodies (Ab-1s) that specifically bind structural, organelle fimbrial proteins of Escherichia coli were able to modulate immune function in anti-Id(fim)-immunized mice. Proliferation or suppression of splenic lymphoid cell responses by polyclonal anti-Ids in tissue culture appeared to be dose dependent. Anti-Ids were able to induce a dose-dependent T-cell-mediated immunity specific for type 1 fimbrial antigen(s) in immunized animals when assessed in vitro, but they failed to elicit in vivo positive ear-swelling skin reactions. Anti-Ids were unable to induce protective immunity against an in vivo infectious challenge with E. coli in anti-Id-immunized adult animals, but they stimulated a specific, secondary antibody response in anti-Id-challenged mice. Anti-Ids stimulated the development of anti-anti-Ids (Ab-3s) specifically binding a fimbrial antigen(s) and revealed the presence of antibody idiotypes binding E. coli adhesin proteins in the 27- to 29-kilodalton range. Results suggest discrete, but subtle, immunomodulatory effects of the anti-Ids and potential vaccinoid properties capable of stimulating a specific humoral and cellular response in vivo.     

Anti-idiotypic immunization provides protection against lethal endotoxaemia in BALB/c mice.

Against lipid A (the conserved moiety of lipopolysaccharides from Gram-negative bacteria) neutralizing IgM monoclonal antibodies (mAb) 8-2 and 26-20 anti-idiotypic (Ab2) mAb were produced: Ab2 mAb KM-04 (IgG1) against mAb 8-2, and Ab2 mAb PW-1 (IgG2a) and PW-2 (IgG1) against mAb 26-20. The binding of Ab2 mAb KM-04 to 8-2 (Ab1) was strongly inhibited by a lipopolysaccharide (LPS) extract from either Salmonella minnesota R595 (Re LPS) or Escherichia coli J5 (Rc LPS), whereas the binding of Ab2 mAb PW-1 and PW-2 to 26-20 (Ab1) was only marginally inhibited by both Re LPS and Rc LPS. The results indicated that Ab2 mAb KM-04 recognizes a lipid A-binding site related idiotope on mAb 8-2 and therefore KM-04 might bear the internal image of a neutralization determining epitope of lipid A. Consequently Ab2 KM-04 might induce antibodies to lipid A. Indeed anti-idiotypic immunization of syngeneic BALB/c mice with Ab2 mAb KM-04 resulted in development of lipid A-binding anti-anti-idiotypic (Ab3) antibodies in serum. Similar immunizations with Ab2 mAb PW-1 and PW-2 were unsuccessful. However, induction of lipid A-binding Ab3 by mAb KM-04 proved to be genetically restricted to BALB/c mice. DBA/2 mice, Swiss mice and rabbits did not develop lipid A-binding antibodies upon immunization with mAb KM-04. In protection experiments, it was shown that BALB/c mice vaccinated with mAb KM-04 showed significantly enhanced survival from challenge with either rough (Re) LPS from Salmonella minnesota or smooth LPS from E. coli 0111:B4 when compared to BALB/c mice immunized with a non-relevant Ab2 mAb. The results suggest that mAb KM-04 constitutes a non-internal image vaccine to the lethal effect of lipid A in BALB/c mice. Furthermore an Ab3 mAb was prepared against Ab2 mAb KM-04 that showed reactivity with Re LPS. This Ab3 mAb, designated LE-21 (IgG2a) protected mice against an otherwise lethal challenge of Re LPS.     

The primary IgM antibody repertoire: a source of potent idiotype immunogens.

A widely held view is that, to elicit adaptive immune responses, most protein antigens must be given with adjuvants that activate the innate immune system. It has also been proposed that the immune system is tolerant to idiotypes (Id) of the syngeneic primary antibody (Ab) repertoire. We now show that among 73 purified noncomplexed secretory IgM monoclonal antibodies (mAb), 4 (5.5%) elicited high levels of IgG Ab against the Id even though no adjuvant was added. The responses were controlled by H2-linked immune response genes. IgG1, but no IgG2a or IgG2b, anti-Id Ab were detected, indicating involvement of T helper type 2 (Th2) cells. All 4 IgM mAb are likely germ-line gene-encoded, and 1 was shown to represent a recurrent Id. After endotoxin depletion the most potent immunogen of the 4 still provoked robust humoral anti-Id responses. The results suggest that a natural protein of the primary IgM Ab repertoire can be immunogenic without an adjuvant.     

Anti-anti-IgE idiotypic antibodies mimic IgE in their binding to the Fc epsilon receptor

The binding site of some anti-idiotypic antibodies (anti-Id) can appear as a structural image of the antigen and as such may mimic its biologic activity. We raised anti-anti-IgE antibodies in an attempt to obtain anti-Id capable of interacting with the Fc epsilon receptor (Fc epsilon R). Guinea pigs were immunized with purified murine monoclonal antibodies (mAb) that had been found to react with epitopes closely related to the site on the IgE molecule which is recognized by the Fc epsilon R. After only two injections, we could detect in the immune sera anti-Id that inhibited the binding of IgE to the anti-IgE mAb used as immunogens. However, only after 10 immunizations over a period of about 6 months could we detect antibodies that competed efficiently with the binding of IgE to rat basophilic leukemia (RBL) cells. The "IgE-like" anti-Id could be affinity purified from immunosorbents made of the anti-IgE mAb. F(ab')2 and Fab' fragments were as effective inhibitors of IgE binding as the intact anti-anti-Id antibodies. Some of the anti-Id caused RBL degranulation and all of them, like IgE, inhibited the binding of specific anti-Fc epsilon R mAb to RBL cells. In summary, by hyperimmunization with anti-IgE mAb we could obtain anti-Id whose antigen-binding site is recognized by the mast cell receptor specific to the Fc portion of IgE.