Control idiotope expression by monoclonal anti-idiotope antibodies

Development and selection of marginal zone B cells

It is now clear that functionally distinct subsets of mature peripheral B cells exist. Of these subsets, marginal zone (MZ) B cells in the spleen are strategically positioned at the blood-lymphoid interface and are programmed to initiate a fast and intense antibody response to blood-borne viral and bacterial agents. Their ability to respond vigorously to antigen and polyclonal activators make MZ B cells key players in the early response to pathogens in the bloodstream. The specialized functions of these innate-like lymphocytes bridge the gap between the early innate immune response and the slower adaptive antibody response, affected mainly by the more prolific follicular B cells. MZ B cells, like B1 cells, are important not only to combat infections but also in the maintenance of host homeostasis. Here we discuss some aspects of MZ B-cell selection and function in health and disease.

Characteristics of auto anti-idiotypic antibodies reactive with antibodies expressing the pathogenic idiotype, IdLNF1, in the (NZB x SWR)F1 model for lupus nephritis and its parental strains

The F1 cross between SWR and NZB mice, SNF1, develops severe immune complex glomerulonephritis, in a similar manner to humans with systemic lupus erythematosus (SLE). Our previous data indicate that the idiotypically-related family of antibodies, IdLNF1 may play a role in the pathogenesis of this nephritis. The sera of SNF1 mice, but not NZB or SWR, contained high titers of IdLNF1+ IgG antibodies, which peaked at 22-24 weeks, coinciding with an increase in the CD4 to CD8 ratio of IdLNF1-reactive T cells and IdLNF1 Ig (IgG + IgM) deposition in the kidney glomerulus. Here, auto anti-IdLNF1 antibody levels were quantitated as the mice aged and were found to be significantly different in the three strains, particularly after 20 weeks of age. Moreover, auto anti-IdLNF1 antibody levels were decreased only in SNF1 mice at 20-24 weeks of age. Auto anti-IdLNF1 antibodies were purified by affinity chromatography; anti-IdLNF1 antibodies derived from SNF1 appeared to be of the Ab2 beta or gamma type, while those from SWR mice were Ab2 alpha. Thus, differences in the specificity of auto anti-idiotypic antibodies may be critical in the regulation of the IdLNF1 idiotype in SWR and SNF1 mice, and the development of nephritis in SNF1 mice.

Anti-idiotypic antibodies as surrogate antigens for vaccinating against the cattle tick, Boophilus microplus

QU13, a monoclonal antibody (mAb) raised against midgut (GM) antigens from Boophilus microplus and shown to recognise antigens which protect cattle from tick challenge was used to immunise cattle and rabbits to produce anti-idiotypic antibodies (AIA). Polyclonal antisera against mAb QU13 were produced in rabbits and cattle. AIA were purified from these antisera by affinity chromatography procedures. These purified AIA were found to block mAb QU13 binding to GM in enzyme-linked immunosorbent assay (ELISA). AIA purified from bovine antiserum elicited an immune response in cattle to antigens extracted by detergent from the midgut of B. microplus (TXGM) after the fourth vaccination (P = 0.06) compared with the bovine immunoglobulin (Ig) control. The mean antibody level in the group of experimental cattle vaccinated with AIA purified from rabbit antisera was significantly higher (P < 0.03) than that of bovine Ig control cattle after the fourth vaccination and an anamnestic response (P < 0.11) occurred in the rabbit AIA vaccinated group of cattle when a single booster dose of 300 micrograms of TXGM was given after the first tick challenge. The positive control group of cattle vaccinated with TXGM were significantly protected (P < 0.05) against tick infestation after the booster dose of 300 micrograms of TXGM. The AIA vaccinated groups of cattle were not protected against challenge with 20,000 larval ticks either before or after the booster injection of 300 micrograms of TXGM.

Idiotypic vaccination: immunoprotection mediated by anti-idiotypic antibodies with antibiotic activity

Anti-Id antibodies were raised in mice against a monoclonal antibody (MoAb KT4) that neutralized the in vitro activity of a Pichia anomala yeast killer toxin. Monoclonal antibody was administered to BALB/C syngeneic mice with different schedules of immunization before intravenous challenge with increasing amounts of yeast killer toxin-sensitive Candida albicans cells. The course of candidosis was studied in comparison with mice non-immunized and immunized with an isotype-matched unrelated MoAb subdivided into control groups. Protection was reflected by statistically significant increases in survival rate of mice immunized with MoAb KT4 which showed variable serum levels of yeast killer toxin-like anti-Id antibodies. MoAb KT4 affinity chromatography purified mouse anti-Id antibodies were capable of killing in vitro the yeast cells of the Candida albicans strain used for the experimental infection. This is the first report of antimicrobial protection that exploits the role of anti-idiotypic antibodies presumably acting in vivo as antibiotics (idiotypic vaccination).

Exposure of female mice to type II collagen reduces susceptibility to collagen-induced arthritis in offspring

The effect of exposure of female DBA/1 mice to collagen II (CII) prior to breeding on the susceptibility of their offspring to CII-induced arthritis (CIA) was investigated. It was found that female offspring, born within 3 months after exposure of the mothers to CII, had a significantly reduced incidence of CIA, following immunization with CII. Just prior to this immunization, no anti-CII could be detected in the offspring. Offspring born more than 3 months after exposure of the mothers to CII showed no differences in susceptibility to induction of CIA, if optimal conditions for induction were used. However, when suboptimal conditions for induction of CIA were used, offspring of females that had been exposed to CII developed less severe arthritis and had a delayed onset of arthritis as compared with controls. It is concluded that exposure of female mice to CII prior to mating results in changes in the immune response to CII in the offspring, leading to a subtle decrease in susceptibility to CIA.

The role of germline gene expression and somatic mutation in the generation of autoantibodies to DNA

Several distinctive features of anti-DNA autoantibodies have been identified by a detailed analysis of the available heavy and light chain sequences. They include unique VH gene segments that are not normally expressed in antibodies to external antigens, somatic mutations which may serve to change the antigenic specificity as well as to increase affinity, a less stringent choice of light chains, and a unique basic peptide in the heavy chain CDR3. It is proposed that in the majority of cases, the regulatory mechanism of self-tolerance in the healthy animal operates via VH gene expression to prevent the synthesis of potentially high affinity anti-DNA autoantibodies.

Cellular changes during the infusion of high dose intravenous immunoglobulin

With the ever widening group of autoimmune conditions that are beneficially affected by infusions of high dose immunoglobulin the possible mechanisms of action of such therapy appear increasingly complex. Fc mediated blockade of the mononuclear phagocyte system is an acknowledged early effect. This is, however, accompanied by a decrease of neutrophil counts which suggests that IgG binding to the neutrophil may be a mechanism of action. The decrease of neutrophil counts is transient but in immune thrombocytopenia is inversely proportional to the platelet response observed. In parallel to the effect on the neutrophil there are changes in the lymphocyte subsets with reversal of the T helper/suppressor ratio and alterations in the individual cellular constituents of each subset that correlate with the clinical response. The observed changes in B cell numbers and function suggest that T dependent and independent antibody production is effected by intravenous immunoglobulin. It is increasingly clear that in ITP at least the clinical response to IV IgG is a summation of several cellular events and their balance reflects the ultimate outcome. It may eventually be possible to use these observations to predict the likely outcome in the individual patient of this mode of therapy.

Antiidiotypic antibody vaccine in murine Schistosomiasis mansoni comprising the internal image of antigen

This study presents the characterization of an experimental immunotherapeutic approach for schistosomiasis utilizing antiidiotypic antibodies. Antiidiotype (31-3B6) was generated in rabbits using a protective murine monoclonal antibody 31-3B6 which recognizes a 68,000-D molecular mass glycoprotein present in extracts of Schistosomiasis mansoni adult worm homogenetics. Immunization of mice with antiidiotype (31-3B6) before S. mansoni cercariae infection resulted in protection levels ranging from 16 to 41% depending on the route of administration of antiidiotypic antibody and the use of adjuvant. Levels of protection as high as 25% could be obtained with a single injection of antiidiotype (31-3B6) without the use of adjuvant. Animals noted to be resistant to infection with S. mansoni cercariae were also noted to exhibit a humoral immune response that bound components of S. mansoni adult worm homogenetics. This induced antiantigen immune response was shown to bind to the surface of S. mansoni schistosoma by indirect immunofluorescence. Further characterization of the induced antiantigen response showed that a portion (3-32%) of the induced humoral immune response portrayed the binding specificities of the murine monoclonal antibody 31-3B6. The data indicate that antiidiotype antibodies generated utilizing defined monoclonal antibodies can act as surrogate antigens in the protection of infection in schistosomiasis.

Idiotypic control of the immune response

Anti-idiotypic antibodies are antibodies against the antigenic determinants (idiotypes) of an antibody's antigen-binding region. Anti-idiotypes can bind near (Ab2 gamma) or away (Ab2 alpha) from the antigen-combining site or can carry the internal image of the antigen (Ab2 beta). Idiotypes and anti-idiotypes have been described in T- and B-cell systems. They have been used in basic research to purify and characterize receptors and ligands against receptors, to treat tumors, to make vaccines and to diagnose and suppress the immune response. In experimental myasthenia gravis anti-idiotypes protect animals against the disease, block idiotype binding and share idiotypic specificities.

Long-lasting thymus-independent immune responses to anti-idiotype lipopolysaccharide conjugates require continuous B cell renewal

In the present investigation, we have studied the antibody response of both C57BL/6 lipopolysaccharide-responder mice (B6 LPS-R) and C57BL/10ScCr LPS-nonresponder mice (B10.Cr LPS-NR) upon immunization with copolymers of LPS and either Ac38 or Ac46 anti-idiotypes. As both strains of mice studied are of the Ighb allotype the antibody response obtained was quantified by estimating the serum levels of the complementary idiotype, B1-8, in immunized mice. The results show that while the injection of the LPS-R strain B6 with copolymers of LPS anti-idiotype resulted in a long-lasting idiotype response the immunization of the LPS-NR strain, B10.Cr, resulted in virtually no response. This finding allowed us to perform cell transfer experiments to study the response of isolated cells from B6 mice transferred into LPS-NR hosts. Using such a cell transfer model, the results obtained suggest that long-lasting idiotype responses observed in the LPS-R strain require continuous B cell production in bone marrow. The relevance of this finding to the understanding of the long-lasting (fluctuating) antibody responses to nondegradable thymus-independent polysaccharides is discussed.

Binding specificity of antiidiotypic autoantibodies to anti-DNA antibodies in humans

Human antiidiotypic antibodies to anti-DNA antibodies can be separated into at least two categories based on their binding to anti-DNA, antiidiotypic antibodies, and antigens. One type was found mainly in inactive stage of SLE. The antiidiotypic antibodies appear to be directed towards idiotype (Id) determinants in the antigen-binding sites of anti-DNA antibodies. Antibody from patient T.K. acted like a mirror image of anti-single-stranded DNA antibodies, O-81, as determined by a competitive inhibition RIA. Antibodies from patient S.U. also seemed to be Ab 2 beta and Ab 2 gamma to anti-double-stranded(ds) DNA antibodies, NE-1. Most of normal subjects, on the other hand, had antibodies that bound to the human monoclonal anti-ds DNA antibodies, NE-1, NE-13, 7F4, and O-81. The Id-anti-Id interaction was not inhibited by the addition of DNA. Thus, normal subjects had Ab2 alpha activity that recognizes Id determinants in the framework region common among anti-DNA antibodies, whereas antiidiotypic antibodies in most SLE sera appear to show Ab 2 beta and Ab 2 gamma activity. The results provide evidence that the Id network system regulates immunological tolerance to DNA in humans.

Anti-idiotypic antibodies as immunogens: idiotype-based vaccines

Numerous studies have documented that antibodies may regulate the immune system and form the basis of vaccines, namely anti-idiotype vaccines. Antibodies carry individual idiotype antigenic determinants against which antibodies can be formed. When the anti-idiotype recognizes the same site that recognizes the primary antigen, a mirror image or combining site antibody may be generated. Other anti-idiotypes which recognize non-combining antigenic determinants have also been used. The evidence is reviewed for the existence of a broad range of anti-idiotypes and details are given of how an anti-idiotype vaccine based on the hepatitis B surface antigen has protected against virus challenge in the most relevant animal model system, namely the chimpanzee. Furthermore, the definition of the CD4 molecule as the conserved binding site for all known human and similar immunodeficiency viruses, (in marked contradiction to their varied neutralizing properties) has led to the raising of anti-idiotypes in mice based on the CD4 receptor which have the capacity to neutralize a broad range of isolates.

In vivo activation of quiescent B cells by anti-immunoglobulin. II. Production of lysozyme-specific monoclonal antibodies of desired isotype

We wished to determine whether injection of mice with anti-isotype antibody would be a means to regulate in vivo isotype expression and to obtain hybridomas secreting monoclonal antibodies (mAbs) of desired antigen specificity and isotype. Treatment with a rat mAb (7D2) reactive with both the IgG2a and IgG2b isotypes of mouse Ig resulted in large increases in the serum concentrations of mouse IgG2(a + b). Moreover, injection of antigen-7D2 conjugates had a profound effect on the isotype distribution of hybridomas subsequently obtained from these animals. Thus, while greater than 95% of anti-hen eggwhite lysozyme (HEL) mAbs prepared from mice immunized with HEL alone were of the IgG1 isotype, 12/15 (80%) of the mAbs from mice injected with HEL-7D2 conjugates were of the IgG2a or IgG2b isotype. When tested for effector functions using HEL-coated erythrocytes, the mAbs showed the expected activities, i.e., the IgG2, but not IgG1 anti-HEL mAbs were able to fix complement, bind protein A, and mediate antibody-dependent cytotoxicity and phagocytosis. These results indicate that in vivo immunization with anti-isotype-antigen conjugates can be used to produce hybridomas of predetermined antigen and isotype specificities.

Anti-idiotypic antibodies and the induction of specific tumor immunity

Immunization with anti-idiotypic antibodies is a strategy which, with variable success, can be used to elicit or amplify antigen-specific immune response. This article discusses the manipulation of specific idiotypes in anti-tumor immunity, emphasizing the appropriate consideration of genetic restriction, the choice of idiotype specificity, and the route of immunization. Two independent pathways are outlined: One uses anti-idiotypic antibodies to select and amplify tumor-specific T and B cells via their preexisting antigen-specific receptors, and the other uses anti-idiotypes as primary internal image immunogens to elicit immune recognition of determinants shared by the anti-idiotype and by tumor-associated antigens. Both pathways can be manipulated in attempts to favor the generation of anti-tumor effector cells and minimize the elicitation of suppression. Anti-idiotypic immunization can be utilized to induce therapeutic immune reactivity in hosts lacking effective direct anti-tumor responses. By stimulating 'silent', or normally suppressed, T and B cell clones, appropriate immunization strategies can circumvent immune regulatory pathways associated with suppressor cells and factors derived from such cells. In these studies, adequate characterization of antitumor idiotype and anti-idiotype specificities is key to the experimental approach to tumor therapy using antibodies. The importance of individual host genetic variation in the specificity and scope of immune response to anti-idiotypic immunoglobulins is unknown, and remains an important potential barrier to therapeutic management.

Studies on the suppression of the immune response to a defined protein epitope by anti-idiotypic antibodies

We have previously reported that C3H.SW (CSW) and A/J mice immunized with the tobacco mosaic virus protein (TMVP) produce antibodies to a decapeptide epitope corresponding to amino acid residues 103-112 of the protein. In the C3H.SW (CSW) strain, the antibodies to the decapeptide contain major crossreactive idiotope, C10-IdX, which is found on a CSW-derived monoclonal antidecapeptide antibody, designated as C10. The in vivo administration of anti-C10 antibodies suppresses the response to the decapeptide epitope in CSW mice. The present communication describes experiments designed to elucidate several parameters responsible for the suppression produced by the in vivo administration of anti-C10. It was found that 50 micrograms of anti-C10 was required to suppress the response to the decapeptide in CSW mice when 2 weeks elapsed between administration of the anti-C10 and immunization with TMVP; however, only 10 ng was required when one injection of antigen instead of two was administered and when the interval between treatment with anti-C10 and immunization was extended to 6 weeks. This suggests that the anti-C10 induces alterations in the idiotypic network which are not yet fully developed after 2 weeks. Furthermore, experiments presented herein demonstrate that decapeptide-binding antibodies from A/J mice, which lack the C10-IdX, were also suppressed by pretreatment with anti-C10. Interestingly, unlike the case with the CSW strain, the titer to TMVP was decreased by the administration of anti-C10 to A/J mice which were subsequently immunized with TMVP. These findings suggest that the polyclonal anti-C10 contains antibodies to an idiotype which is a major component of the overall anti-TMVP response of A/J mice and may be important in the overall regulation of the anti-TMVP response.

Idiotype-directed interactions during ontogeny play a major role in the establishment of the adult B cell repertoire

IgM hybridomas derived from perinatal B cells show a high degree of auto-reactivity and many had demonstrable anti-idiotypic reactivities by binding studies. Selected multispecific antibodies were also shown to have potent idiotype-specific biological activities and if administered at appropriate stages of development could dramatically alter the responses of these mice when challenged with appropriate antigens in adult life. The results obtained suggest that idiotype-directed interactions between neonatal B cells play an important role in the early establishment of the B cell repertoire which is subsequently expressed in adult mice.

Effects of anti-IgM on mitogen-induced proliferation of human B-lymphocyte malignancies

Therapeutic trials of anti-immunoglobulin antibody have produced a wide range of responses in attempts to control the growth of human B lymphoid neoplasms. This variability might reflect differences in intrinsic functional characteristics of malignant B lymphocytes that determine susceptibility to anti-immunoglobulin-mediated regulation of growth. To characterize B-lymphocyte malignancies, tissue samples from 24 patients were studied during short-term culture in vitro. Malignant B lymphocytes were stimulated to proliferate by the T-independent mitogens lipopolysaccharide, cytochalasin B, and Staphylococcus aureus that bears protein A. The effects of monoclonal mouse anti-human IgM on mitogen-induced malignant lymphocyte proliferation were then assessed. Mitogen-induced responses of malignant lymphocytes from three patients were abrogated by 2 micrograms/ml monoclonal anti-human IgM. Proliferation was also abrogated by polyclonal goat anti-IgM antiserum but proliferative responses were not affected by control monoclonal antibody. Further study showed that anti-immunoglobulin-mediated inhibition of proliferation was not dependent on Fc-determined interactions, nor was it dependent on the presence of T lymphocytes. These results indicate that a subset of human B-lymphocyte malignancies are susceptible to inhibition of proliferation mediated by anti-IgM.

Trypanosoma rhodesiense: variable effects of cyclophosphamide on antibody production, survival, and parasitemia in infected mice

Mice of the CBA/CaJ strain, infected with Trypanosoma rhodesiense, were injected with a single high dose (approximately 200 mg/kg) of the immunosuppressive drug cyclophosphamide to determine if an induced, transient inability to make antibody affected survival or parasitemia. When given on the day of infection, the drug had no significant effect on survival. It delayed, but did not prevent, the appearance of specific antibodies and the clearance of the infecting trypanosome variants. When cyclophosphamide was injected 1 week after infection, survival mass significantly decreased. Antibody production to specific variant antigens and to common trypanosome antigens were terminated, but the mice were able to eliminate the infecting trypanosomes. These findings suggest that a temporary inability to make antibody to trypanosomes does not result in more rapid death when only the infecting trypanosome variant is present. However, immunosuppression may accelerate death if it occurs when there are many different types of trypanosomes present.

Further characterization of internal image-bearing anti-idiotypic antibodies: specific binding to immunoglobulin receptors on murine hybridoma cells secreting antibodies to hepatitis B surface antigen

The further characterization of internal image anti-idiotypic antibodies (anti-Id) that represent a potential alternative vaccine candidate for type B viral hepatitis is described. The anti-Id preparation contains an internal image component or related epitope that mimics hepatitis B surface antigen (HBsAg) and binds to murine hybridoma cells that secrete antibodies to HBsAg (anti-HBs). This binding to anti-HBs-secreting hybridomas was partially inhibited by intact HBsAg particles and was associated with the expression of an interspecies idiotype. Immunoprecipitation studies demonstrated that the anti-Id bound to immunoglobulin molecules expressed on the surface of the hybridoma cells. These data suggest that internal image anti-Id, which induces an in vivo antibody response by antigenic mimicry in the absence of HBsAg, binds to anti-HBs molecules on the surface of cells actively secreting anti-HBs. The possible mechanism for internal image anti-Id-based antibody vaccines that mimic the overall conformation of antigens associated with infectious agents is discussed.

Regulation of the immune response. II. Concomitant idiotope-specific enhancement and suppression can result in a phenotypically normal response

Idiotope-specific immunoenhancement or suppression was induced in C57BL/6 mice by the injection of physiological amounts (100 ng-10 micrograms) of monoclonal anti-idiotope antibody. As previously described, nanogram doses enhanced idiotope expression while a 10-micrograms dose of anti-idiotope antibody induced the activation of a population of Thy 1.2+, Lyt 1-, 2+ suppressors. Both positive and negative regulatory activities were confined to the non-mu, idiotope+ compartment of the plaque-forming cell response. Administration of intermediate doses of anti-idiotope antibody resulted in an immune state indistinguishable from that of naive mice. This apparently normal response was in fact the product of a simultaneous activation of balanced enhancing and suppressive activities. When treated with anti-Lyt 2 or Lyt 1 and complement, spleen cell populations taken from such phenotypically "naive" mice revealed latent idiotope-specific immunoenhancement or suppression, demonstrating the components of a functional regulatory equilibrium.

Effect of passive administration of alloantiserum containing antibody against putative acceptor(s) for T cell-replacing factor (TRF) in the neonatal stage on development of B cell activity responsive to TRF

Previously, we showed that the antiserum raised in male (DBA/2Ha X BALB/c)F1(DCF1) mice (T cell-replacing factor [TRF]-low response animals) by immunizing them with activated B cells from BALB/c mice (TRF-high-responders) contained antibodies against putative TRF-acceptor site(s). We have now evaluated the hypothesis that neonatal treatment of mice with the above antiserum suppresses the development of B cells responsive to TRF. Male DCF1 mouse anti-BALB/c B-cell antiserum or normal DCF1 mouse serum as a control was injected into BALB/c mice within 24 hr after birth. In the antiserum-treated mice, no augmented primary immunoglobulin M (IgM) antibody responses to sheep red blood cells (SRBC) were observed under the conditions in which markedly augmented IgM anti-SRBC responses were induced in control BALB/c mice, suggesting that development of B cells reacting with male DCF1 mouse anti-BALB/c B-cell antiserum is suppressed by the neonatal treatment with the antiserum. Furthermore, the development of B cell activity responsible for helper factors derived from T cells, such as TRF, was markedly suppressed in the neonatally antiserum-treated mice, whereas activity of B cells capable of interacting directly with helper T cells through antigen-bridges was not significantly affected by the same treatment. Such suppression of the B cell activity could be induced only when the antiserum was administered within 48 hr after birth. Moreover, neonatal treatment of mice with the antiserum induced suppressed responsiveness of B cells to a T-independent type 2 antigen, TNP-Ficoll. Neither serum-borne suppressive serum components nor suppressor cells were detected by the system employed. These results support the hypothesis that TRF responsive B cells constitute a subpopulation distinct from the other B cells capable of cooperating with helper T cells via cognate interaction.

Strain-specific silencing of a predominant antidextran clonotype family

The immune response to dextran is characterized by marked phenotypic differences among murine strains. In particular, Igha strains, as opposed to strains of other Igh haplotypes, respond relatively vigorously to dextran B1355 fraction S (DEX), producing predominantly antibodies bearing the lambda light chain, and specific for the alpha(1----3) glucose linkage. We have investigated this disparity in BALB/c (Igha) vs. C.B20 (Ighb) mice at the individual precursor cell level. Consistent with previous findings (7-9, 35, 40, 42, 43), there was a 10-fold higher frequency of lambda-bearing splenic B cells specific for the alpha(1----3) linkage in Igha mice. As with previously studied (25-27) predominant specificities, the origin of this high frequency of lambda-bearing alpha(1----3) DEX-specific B cells appears to be a reflection of a high expression of this specificity in surface Ig (sIg)-negative cells emerging from the bone marrow generative cell pool. Surprisingly, although C.B20 mice (Ighb) have a low frequency of lambda-bearing alpha(1----3) DEX-specific B cells in their mature primary splenic population, the frequency of precursor cells of this clonotype in their sIg- bone marrow cell population is equivalent to that of BALB/c sIg- cells. These cells could only be stimulated in allotype allogeneic (Igha), as opposed to allotype syngeneic (Ighb), carrier-primed irradiated recipients. This finding was confirmed by the finding that a high proportion of antidextran hybridoma cell lines derived from C.B20 bone marrow cells produced lambda-bearing alpha(1----3) DEX-specific antibodies that were IdX+. These findings have led us to conclude that the well-established phenotypic difference between Igha and Ighb mice with respect to the expression of lambda-bearing alpha(1----3) DEX-specific antibody responses is not, as previously assumed, the result of an inability of Ighb mice to generate B cells of this clonotype, but rather, is the product of environmental, possibly antiidiotypic, silencing of cells of this clonotype as they mature in Ighb mice.

Effects of phosphorylcholine-lipopolysaccharide conjugates on the induction of anti-idiotype-mediated B-cell tolerance

Preincubation of BALB/c spleen cell cultures for 24 hr with phosphorylcholine (PC)-containing antigen together with antibody against the major idiotype (id) of anti-PC antibody renders them irreversibly unresponsive to subsequent stimulation with the antigen alone. In contrast, cultures preincubated for 24 hr with anti-id antibody, either alone or together with lipopolysaccharide (LPS), resulted in an anti-PC response comparable to that induced in control cultures incubated with mock anti-id antibody. After such a 24-hr preincubation with anti-id antibody and various PC-LPS conjugates possessing intact activity for polyclonal B-cell activation, the anti-PC response was inversely proportional to the epitope (PC) density on the LPS conjugates. In addition, similar preincubation of cultures with a non-mitogenic low dose of PC-LPS in the presence of anti-id antibody induced suppression of the anti-PC response as observed with a specific antigen. These results suggest that specific epitope delivers an additional tolerogenic signal during induction of B-cell suppression by anti-id antibody. This epitope effect cannot be replaced by, and is antagonistic to, the mitogenic signal of LPS in the course of B-cell inactivation.

Anti-idiotope vaccines: can they exist?

Idiotopes and idiotypes are determinants on antibody molecules and lymphocyte receptors which confer a degree of uniqueness to these molecules; a number of the idiotypes are associated with the paratope (antigen-combining site) of the antibody. Since idotypic determinants can be recognized as 'foreign' by the autologous immune system, both antibodies and lymphocyte receptors which are anti-idiotypic in function can be found. Hence, anti-idiotype antibodies against paratope-associated idiotypes (Idp) would themselves have paratopes of similar conformation to the epitope on the antigen with which the Idp-bearing antibody reacted. These are the 'internal image' anti-idiotype antibodies. Vaccination of animals with such anti-idiotype preparations should result in the production of Idp-bearing antibody molecules. If these Idp antibodies were protective against infection by a particular pathogen, then the anti-idiotope [anti-(Idp)] preparation would be considered a surrogate antigen. Such anti-idiotype surrogate antigens have been identified, but they were polyclonal and their composition is not, as yet, completely understood. Monoclonal 'internal image' anti-idiotype antibodies have not proved to be consistently successful surrogate antigens. This may reflect a requirement for a minimum avidity of reaction, and antibody specificities in addition to that of the 'internal image'. Further insight into the composition of the polyclonal surrogate antigen is required before elaboration on an 'anti-idiotope vaccine' can be provided.

Cloning of mitogen- and antigen-reactive B lymphocytes on filter paper discs. I. A description of the technique and of methods for the analysis of colonies

A novel technique for establishing short term clones of antigen- or mitogen-activated splenic B lymphocytes is described. Spleen cells are plated onto the surface of filter paper discs and subsequently stimulated by antigen or mitogen in situ; activated B cells proliferate and differentiate into pure colonies of cells analogous to bacterial colonies growing on agar. These colonies of lymphocytes may be characterized in a series of replica hemolytic-plaque, autoradiographic, or immunoenzyme assays making possible a full characterization of the frequency of secreted idiotopes and paratopes and of the cells that produce them. Colony induction by either antigen or mitogen occurs under identical conditions, thus a rigorous comparison between the mitogen-selected and antigen-selected antibody repertoires may be made.

Enhancement of viral hepatitis B antibody (Anti-HBs) response to a synthetic cyclic peptide by priming with anti-idiotype antibodies

In vivo injections of anti-idiotype antibodies were used to prime the immune system of mice to hepatitis B surface antigen (HBsAg). Anti-idiotype reagents in conjunction with a cyclic synthetic peptide analogous to positions 122-137 of HBsAg induced an antibody response to HBsAg (anti-HBs) comparable to that obtained with a single injection of intact HBsAg particles. In addition, high anti-HBs titers were produced in mice injected with HBsAg following anti-idiotype priming. These data indicate that anti-idiotype antibodies may be useful in priming the immune system of a host to a potential infectious agent.

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.

Antiidiotype modulation of herpes simplex virus infection leading to increased pathogenicity

Antiidiotype reagents that recognize idiotypic determinants associated with the combining site of monoclonal antibodies to herpes simplex virus type 2 ( HSV2 ) were used to manipulate the immune response to HSV2 in BALB/c mice. The injection of antiidiotype antibodies into mice before challenge with a 50% lethal dose of HSV2 resulted in a shorter survival time than that of mice receiving either preimmune rabbit immunoglobulin G or antiidiotype reagents against hepatitis B surface antigen before HSV2 challenge. These findings indicate that the immune response to HSV2 in mice can be modulated through idiotype- antiidiotype networks, thereby increasing the pathogenicity of HSV2 infections.

Mechanism of neonatally induced idiotype suppression and its relevance for the acquisition of self-tolerance

We present an analysis of the elimination of a monoclonal anti-idiotope antibody injected into C57BL/6 mice on the day of birth. During the first 4 weeks of life the antibody is eliminated from the circulation with a slow half-life, ranging from 15-18 days. This finding makes sense biologically as the animals depend at that time on maternally transmitted antibodies. After 4 weeks elimination speeds up considerably. The rate of elimination appears to be the same for a 1 microgram and a 100 microgram dose. The elimination data and previous results on the specificity, duration and cellular basis of idiotype suppression induced by the monoclonal anti-idiotope fit into the following model of idiotype suppression, which is in good accord with other experimental evidence on idiotype and allotype suppression in the literature: suppression depends strictly on the concentration of anti-idiotope in the cellular environment. As long as it is in the microgram range, the generation of idiotope-bearing B cells from pre-B cells is prevented. The system recovers quickly from this type of suppression, as soon as the concentration of anti-idiotope falls below that range. A second type of suppression is also induced in the anti-idiotope-treated animals. It is long-lived (8-10 weeks longer that the first type), has a peculiar specificity in that it affects, in our particular case, only a certain subset of the antibodies bearing the target idiotope, and involves regulatory T (and possibly B) cells which prevent the functional maturation of B cells expressing those antibodies in the animal. Suppression of this type also depends strictly on anti-idiotope concentration and is induced either at the time when the generation of idiotope-bearing B cells from pre-B cells is still inhibited or just thereafter, when such cells begin to appear in the system and the anti-idiotope concentration is still at a few hundred nanograms per ml. Experimental evidence indicates that in the induction of suppression, the primary target of the anti-idiotope are idiotope-bearing antibodies variable regions. We assume that those variable regions, complexed by anti-idiotope are the inducers of regulatory (suppressive) T cells. Idiotype suppression may also be induced upon interaction of antibody variable regions (and possibly other receptors) with ligands other than anti-idiotypic antibodies. We, therefore, think that idiotype suppression not only establishes self-tolerance within the antibody system, but is a mechanism of self-tolerance in general.

Induction of idiotope suppression in the anti-azophenylarsonate response of T-depleted A/J mice

The homologous, monoclonal antiidiotope, MB, induced idiotope suppression that was remarkably stable and could be transferred by B lymphocytes. Marked depletion of T cell function, confirmed by limiting diluting analysis, did not affect the ability of MB to suppress the corresponding idiotope. Suppression induced by MB appears to result from direct interaction with idiotope-positive B cells, without the intervention of idiotope-specific T suppressor cells.

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.

The molecular biology of immunoglobulin D

Immunoglobulin D (IgD) is co-expressed with immunoglobulin M (IgM) on the membranes of most B cells, yet its biological function has remained a mystery. Recent detailed information on the structure and transcription of the unusual IgD heavy chain (delta) gene in mouse suggests a complex genetic control. A model is presented for the developmental regulation of IgM and IgD and roles suggested for the membrane and secreted forms of IgD in the immune network.

Analysis of idiotypic heterogeneity in the anti-alpha 1-3 dextran and anti-phosphorylcholine responses using monoclonal anti-idiotype antibodies

Panels of monoclonal anti-idiotype antibodies (MAIDs) specific for individual (IdI) and cross-reactive (IdX) idiotopes were prepared and used to study the expression of these idiotopes on anti-DEX and anti-PC antibodies produced in response to antigenic stimulation in vivo, clonal expression of idiotopes in an in vitro splenic focus assay, and the alterations in the idiotypic profile of these responses after in vivo administration of monoclonal anti-Id antibodies. Using these panels of MAIDs, it was possible to inactivate IdI-bearing B cells both in neonates and adult mice without affecting the responsiveness of IdI- B cells. By contrast, suppression with IdX-specific antibodies resulted in greatly reduced antibody responses. By studying the idiotypic profile of anti-DEX clones in the splenic focus assay, it was shown that IgM, IgG, and IgA antibody Id were diverse and paralleled those expressed in serum. Within some clones there was evidence that idiotope-isotype associations differed, suggesting that V region variants may have been generated within the progeny of a clone following stimulation by dextran. An anti-anti-Id antibody isolated from a BALB/c mouse undergoing a normal immune response to R36A was shown to have a T-cell independent highly idiotope-specific regulatory effect on the T15+ anti-PC response, apparently affecting induction of anti-idiotypic B cells.

Anti-idiotypic antibodies induce neutralizing antibodies to rabies virus glycoprotein

Rabbit anti-idiotypic antibodies (alpha Id Ab) were prepared against five murine monoclonal antibodies (mAb) specific for the rabies virus glycoprotein. Four of the mAb were directed against three known, type-specific, neutralizing sites on the glycoprotein, and the other mAb was directed against a topographically uncharacterized, nonneutralizing epitope. An absence of significant cross-reactivity among the alpha Id Ab for heterologous mAb suggested that the alpha Id Ab were highly specific for unique variable region determinants. The binding of three of the five alpha Id Ab to their homologous mAb could be inhibited by rabies virus-soluble glycoprotein, suggesting that the alpha Id Ab possessed subpopulations similar or adjacent to the antigen-binding site of the mAb. Two of the five alpha Id Ab injected into mice elicited a specific virus-neutralizing antibody response. Mechanisms to account for the induction of the virus-neutralizing antibody by alpha Id Ab are discussed.

The occurrence of defined idiotypes on autoantibodies to mouse thyroglobulin

Anti-idiotypic antibodies were raised in rabbits to three monoclonal mouse autoanti-thyroglobulins. Of the idiotypes recognized, one was unique to that monoclonal, while the other two showed evidence of sharing idiotopes with other monoclonal anti-thyroglobulin (TG) idiotypes, the IgM idiotype in particular being found on nearly half of the hybridomas studied. Two of the idiotypes could be detected in the sera of mice with experimental allergic thyroiditis (EAT), but they constituted only a very small percentage of the total anti-TG present. In spite of its low levels in EAT mice the D8 idiotype could be induced by injection of anti-idiotype and TG and in this case it constituted up to 20% of the anti-TG activity in individual mice, showing a strain-related association between the idiotype and autoanti-TG.

Immune response to hepatitis B surface antigen: enhancement by prior injection of antibodies to the idiotype

Anti-idiotype reagents that recognize a common idiotype associated with the combining site of antibodies to hepatitis B surface antigen (anti-HBs) were used to manipulate the immune response to hepatitis B surface antigen in BALB/c mice. The injection of antibodies to the idiotype before antigenic stimulation resulted in an increase in the number of cells secreting immunoglobulin M antibodies to hepatitis B surface antigen. Anti-HBs-secreting cells were also induced by administration of antibodies to the idiotype without subsequent antigen exposure. These findings indicate that the immune response to hepatitis B surface antigen in mice is regulated through an idiotype-anti-idiotype network.