Immunochemical and molecular characterization of regulatory idiotopes expressed by monoclonal antibodies exhibiting or lacking beta 2-6 fructosan binding activity

Murine immune response to Neisseria meningitidis group C capsular polysaccharide: analysis of monoclonal antibodies generated in response to a thymus-independent antigen and a thymus-dependent toxoid conjugate vaccine

Antibody (Ab) responses to polysaccharides (PSs) such as Neisseria meningitidis group C PS (MCPS) are characterized as being thymus independent (TI) and are restricted with regard to clonotype and isotype expression. PS conjugated to proteins, e.g., MCPS coupled to tetanus toxoid (MCPS-TT), elicits a thymus-dependent (TD) response. In order to understand the influence of the form of a vaccine (TI versus TD) on the Ab repertoire, we generated monoclonal antibody (MAb) panels from mice immunized and boosted with MCPS or MCPS-TT in different ways. The panels of MAbs were examined for isotype, fine specificity, affinity, and V(H) gene family usage. The use of MCPS-TT resulted in a shift in the isotype from immunoglobulin M (IgM) and IgG3 elicited in response to the MCPS to primarily IgG1. This isotype shift was accompanied by a change in the fine specificity of the response to the conjugate compared to that of PS. New fine specificities and increased affinity were observed in response to the TD antigen (Ag). Dot blot and Northern analyses of MCPS MAbs revealed that V(H) gene family usage is dominated by V(H)J558, used by 23 of 39 MAbs. V(H)3609 was seen in three MAbs of restricted fine specificity. V(H)Q52, V(H)7183, and V(H)VGAM3-8 were seen in more than one MAb across these panels, while V(H)10 and V(H)X24 were detected only once in response to the TI-2 Ag. All MAbs in the panels utilized kappa light chains, and all functional J(kappa) genes were expressed.

Mutational Analysis of Avidity and Fine Specificity of Anti-Levan Antibodies

Using the polyfructose, bacterial levan, as a model polysaccharide, we analyzed how V regions affect binding in anti-polysaccharide mAbs. Previously, panels of mAb were constructed from bacterial levan-immunized BALB/c and CBA/Ca mice. The BALB/c mAb were mostly germline VHJ606:Vκ11, and a subset contained presumed somatic mutations in the complementarity-determining regions (CDRs) that correlated with increases in avidity for the β(2→1) inulin linkage of levan. The CBA/Ca mAb were more heterogeneous in V gene usage, but a subset of inulin-nonreactive mAb were VHJ606:Vλ and had VH sequence differences in the CDRs from the VHJ606 regions of the BALB/c mAb. In this report, VHJ606 Abs containing various combinations of specifically mutated H and L chains were produced by engineered transfectants and tested for inulin avidity and levan binding. Two presumed somatic mutations seen in CDRs of the BALB/c hybridomas were shown to directly cause marked increases in avidity for inulin (VH N53H, 9-fold; VL N53I, 20-fold; together, 46-fold) but not for β(2→6) levan. Exchange of either positions 50 or 53 in VH or the H3 loop between the BALB/c and CBA/Ca mAb resulted in either fine specificity shift or total loss of bacterial levan binding. Three-dimensional models of the V regions suggested that residues that affect binding to inulin alone are near the edge of the CDR surface, while residues involved with binding both forms of levan and affecting fine specificity are in the VH:VL junctional area.

Antibody response against poly (Glu60Ala30Tyr10) terpolymer and bacterial levan in kappa-deficient mice

In murine species, the kappa (+)-bearing immunoglobulins dominate the antibody (Ab) repertoire with a kappa/lambda ratio of 95:5. The aim of the present study is to investigate the characteristics of the antibody response in kappa-deficient (K-/-) mice immunized with a T-dependent synthetic antigen, poly(Glu60Ala30Tyr10) (GAT) and a T-independent antigen, bacterial levan (BL). K-/- mice were obtained by targeted deletion of the J kappa C kappa gene segments. In response to GAT, K-/- mice respond by producing increasing amounts of anti-GAT Ig lambda 1 and Ig lambda 2 in the primary as well as secondary response, although anti-GAT specific monoclonal antibodies (mAb) raised in K-/- mice are mostly of IgM isotype. The GAT public idiotype, GATIdX, present on all GAT-specific Ab bearing kappa light chain, is not detected in the sera of K-/- mice or on any of the anti-GAT lambda 1 mAb. In response to BL, the amount of Ig lambda 1+ Ab in K-/- mice is comparable to the amount of Ig kappa + Ab in normal mice. However, lambda 2+ Ab are detected neither in wild-type nor in K-/- mice. Like kappa + Ab, the majority of lambda 1+ mAb are specific for beta 2-6 fructosan present in BL and rye levan and, to some extent, express the BL-specific idiotype, A48ld. Our results show that important compensatory mechanisms occur in kappa-deficient mice, restoring their ability to mount immune responses against a variety of T-dependent and T-independent antigens by the alternative usage of the clonally restricted lambda repertoire.

Polymorphism in V kappa 10 genes encoding L chains of antibodies bearing the Ars-A and A48 cross-reactive idiotypes

p-azophenylarsonate-specific antibodies of A/J mice which bear the Ars-A crossreactive idiotype utilize the V kappa-Ars-A gene segment, a member of the V kappa 10 family. Southern hybridization of genomic DNA from several inbred strains using a probe from the 5' flanking region of the V kappa-Ars-A gene demonstrated three patterns of restriction fragment length polymorphisms (RFLP). Six genes corresponding to hybridizing bands were obtained from DNA libraries of C.AKR, PERU and A/J mice, and nucleotide sequence comparisons revealed two allelic groups: AKR1 (Igk-V10.1a), AJ1 (Igk-V10.1b) and PERU1 (Igk-V10.1c); AKR2 (Igk-V10.2a), AJ2 (Igk-V10.2b), and PERU2 (Igk-V10.2c). The Igk-V10.1b gene of the A/J strain is the V kappa-Ars-A gene used in Ars-A idiotype-positive antibodies. The product of the C.AKR allele (Igk-V10.1a) contained four amino acid substitutions in CDR3 as compared with Igk-V10.1b. These substitutions probably explain the failure of AKR mice and other strains with the same V kappa 10 RFLP pattern to provide in genetic crosses a L chain which, together with the A/J VH-ArsA gene product, form Ars-A idiotype-positive antibodies. Also, the nucleotide sequence identity between the Igk-V10.1c and Igk-V10.1b alleles and the Igk-V10.2c and Igk-V10.2b alleles is significantly greater than that seen in comparisons with the Igk-V10.1a and Igk-V10.2a alleles, respectively, suggesting an evolutionary pathway similar to that of the linked Igk-J locus. BALB/c antibodies bearing the A48 regulatory idiotype contain L chains encoded by the BALB/c Igk-V10.1b and Igk-V10.2b alleles. Strongly A48 idiotype-positive antibodies utilize the Igk-V10.1b chain, and weakly A48-positive antibodies use the Igk-V10.2b L chain. The possible effects of amino acid substitutions specified by the Igk-V10.1a, Igk-V10.1c, Igk-V10.2a, and Igk-V10.2c alleles on their ability to provide L chains used in A48 idiotype-positive antibodies are discussed.

Binding specificities of inulin-binding immunoglobulins for sinistrin and oligosaccharides isolated from asparagus roots

The major aim of this study was to further investigate the fine specificity of myeloma proteins recognizing epitopes on fructans. Our studies showed that UPC 61, EPC 109, and a hybrid antibody composed of the heavy chain from UPC 61 and the light chain from EPC 109, UPC 61H:EPC 109L, not only bind to inulin which is a linear fructan of beta (2----1) fructofuranosyl linkages, but also bind to sinistrin, a branched molecule consisting of a beta (2----1) fructofuranosyl backbone with beta (2----6) branch points. The fine binding specificity of these three antibodies for the beta (2----1) fructofuranosyl linkages found in inulin-BSA can be further studied by their binding to fructan oligosaccharides isolated from asparagus roots. From a comparative analysis of the amino acid sequences and the apparent affinity constants (aKa) of UPC 61, EPC 109, and the hybrid for various fructan oligosaccharides, it appears that the light chain of the immunoglobulin molecule makes an important contribution to the binding specificity. Finally we report for the first time that a monoclonal antibody specific for beta (2----6) fructans can also bind specifically to inulin-BSA with a lower affinity. This antibody derives its VH and VL from the VHX24 and Vk10b gene families, respectively, which are different from the gene families utilized by UPC 61 and EPC 109 (VHJ606 and Vk11 gene families).

A highly conserved conformational idiotope on human IgM rheumatoid factor paraproteins of the Wa cross-reactive idiotype family defined by a monoclonal antibody

Human IgM rheumatoid factors have been classified into major (Wa) and minor (Po) idiotypically cross-reactive families on the basis of reactivity with polyclonal anti-idiotypic antisera. Extensive structural studies have revealed that RFs from the Wa CRI family have homologous light chains. The structural basis of this CRI however is not known. In this study we have defined a conformational idiotope requiring the association of the VH and VL of a number of RF from the Wa CRI family for its expression and which thus comprise part of the Wa CRI. A murine monoclonal antibody, G8 specific for the idiotope reacted with 67% of RFs from the Wa CRI family. G8 also reacted with one IgG2K paraprotein with unknown specificity suggesting that the idiotope per se does not confer RF reactivity. Comparative studies of G8 expression relative to previously described sequence-dependent heavy and light chain associated idiotopes suggest that G8 recognises a separate determinant. Furthermore, the G8 idiotope is found on RFs expressing the VHI subgroup of heavy chain. Study of G8 expression in polyclonal IgM in normal sera demonstrated that the idiotope is widely expressed in the population. However, significantly higher levels of IgM bearing G8 were detected in the sera of patients with rheumatoid arthritis.

Induction of antigen-specific immunity with monoclonal anti-idiotypic antibodies in vivo: differences in potency and comparison of immunochemical properties

Anti-idiotypic (Id) antibodies provide a means other than antigen of clone-specific regulation of immune responses, and have been proposed as an alternative form of vaccine. However, the requirements for effective induction of immunity by anti-Id are not understood. Nine monoclonal anti-idiotope antibodies (anti-Id mAb) were derived in the Ia. 7 model system. While all nine anti-Id mAb induced comparable Ab3 responses in vivo as detected by ELISA, there were dramatic differences in the potency of the antigen-specific components of the responses induced by the nine anti-Id mAb. Anti-Id mAb that were indistinguishable in isotype, combining site relatedness, fine specificity on a panel of mAb, end point binding titers, competitive binding and ability to induce Ab3 differed dramatically in their ability to induce antigen-specific immunity in vivo, thus ruling out several models for explaining differences in induction.

Activation of clones producing self-reactive antibodies by foreign antigen and antiidiotype antibody carrying the internal image of the antigen

Because we found in previous work that a high fraction of antibodies exhibiting various specificities bound to glutamic acid 50-tyrosine50 homopolymer (GT) and expressed pGAT cross-reactive idiotype (IdX), we studied the activation of clones producing multireactive antibodies in 1-mo-old MRL/lpr and C3H/HeJ mice bearing VHJ haplotype. The activation of such clones was studied after mice were immunized with GT in CFA, HP20 (an anti-Id MAb carrying the internal image of GT in the D region), and a synthetic peptide corresponding to the D segment of HP20. Our results indicate that immunized mice produced both GT- and self-reactive antibodies. Study of the immunochemical properties of MAb showed that they exhibit multispecific properties and bind with similar-affinity constants to GT or self-antigens such as DNA, Smith antigen (Sm), and IgG2a. An important fraction of antibodies obtained from MRL/lpr mice immunized with HP20 expressed pGAT IdX and some of these antibodies share IdX expressed on anti-DNA, Sm, and rheumatoid factor (RFs) antibodies. The hybridomas producing multispecific autoantibodies use heavy-chain- (VH) and light-chain-variable region (VK) genes from various V gene families, suggesting that they do not derive from the pool of GAT precursors. Sequencing of VH and VK genes of two antibodies show that they can use closely related VHJ558, unmutated VK1, or different VK genes than those used by anti-GT antibodies. Our data demonstrate that clones producing antibodies binding to GT and self-antigens with similar-affinity constants can be activated by foreign or anti-Id antibodies carrying the internal image of the antigen or even by a synthetic peptide corresponding to the D segment of anti-Id antibodies.

Structural correlates of a regulatory idiotope

The A48RI expressed on the ABPC48 and UPC10 beta 2----6 fructosan-binding myeloma proteins is a conformational antigenic determinant encoded by V genes deriving from the VHX24 and VK10 families. In the preimmune repertoire the clones using VHX24 genes rarely express A48 idiotopes, clearly demonstrating that this regulatory idiotope is a minor or silent idiotope. Furthermore, these same VHX24-utilizing preimmune clones are frequently associated with the VK1 gene family which is highly represented in the neonatal and adult repertoires. The clonal expansion occurring subsequent to neonatal injection of minute amounts of anti-Id antibodies leads to selective expansion of A48Id+ clones associated with class switching. Few somatic mutations are observed in preimmune clones, or in those expanded by anti-Id antibodies. The fact that few mutations were observed in the IgG1 clones obtained from animals injected with anti-A48Id antibodies after birth indicates that, in contrast to antigen-induced class-switching, the anti-Id-induced switching is not associated with a highly active mutational process. In contrast to the preimmune clones, or those expanded by anti-Id (in the absence of antigenic stimulation) in which VHX24 is associated with VK regions deriving from various gene families, the clones expanded by anti-Id and fructan resemble A48 by using VHX24 and VK10 genes. Few apparent mutations were also observed in these IgM or IgG3 clones expressing A48 idiotopes. The A48 RI can be expressed on clones producing antibodies specific for various self and foreign antigens, and encoded by V genes deriving from various VH and VK families. These results indicate that key contacting residues bearing A48 conformational idiotypic determinants can be made up by various VH-VK combinations. A comparison of the VH and VL sequences of A48 RI+ mAbs showed that many of the observed somatic mutations could be correlated to decreased IDA10 binding. This comparison allowed identification of specific idiotope-determining regions of VH and VK which could represent contacting residues with anti-idiotypic antibodies. The contributions of these regions to the expression of the A48Id was tested by generating a transfectoma antibody expressing the rearranged VHJ558 gene of the ricin 45 hybridoma and the VK10-Ars-a gene of the 36-65 hybridoma. This transfectoma antibody expresses the idiotope recognized by IDA10 and confirms the conformational nature of this idiotope. There are three amino acid residues shared by VHX24 and VHJ558 antibodies expressing the A48 RI which are important for its expression.(ABSTRACT TRUNCATED AT 400 WORDS)

Nucleotide changes in sequential variants of influenza virus hemagglutinin genes and molecular structures of corresponding monoclonal antibodies specific for each variant

We have generated four monoclonal antibodies specific for one or more members of a series of two sequentially derived PR8 influenza virus variants. Three of these antibodies share cross-reactive idiotypes. The amino acid sequences of these antibodies were determined, and it was found that two of these antibodies use genes from the VH7183 family, whereas the third uses a gene from the VHJ558 family. All four monoclonal antibodies derive from different families of genes encoding the variable region of the kappa chain. The RNA sequence of the parent PR8 virus as well as the RNA sequences of the sequential variants were also determined, and it was demonstrated that the variant hemagglutinin molecules differed from the parent molecule by only a single amino acid interchange. Despite these subtle differences in antigenic structures of hemagglutinin, and the cross-reactive idiotype of the antibodies, their primary structures were very different. These data reinforce the idea that a wide variety of antibody structures exist which are directed against subtly different structures in biologically important antigens.

Molecular basis for expression of the A48 regulatory idiotope on antibodies encoded by immunoglobulin variable-region genes from various families

The idiotype defined by the levan-specific BALB/c myeloma protein ABPC48 (A48) has previously been encountered only in antibodies the variable regions of which derive from the VHX24 and V kappa 10 gene families. We have demonstrated expression of the idiotope recognized by the monoclonal anti-A48 idiotype antibody IDA10 on five monoclonal antibodies from different mouse strains, with different specificities including foreign and self antigens and deriving their variable regions from families other than VHX24 and V kappa 10. We analyzed variable region protein structure (deduced from nucleotide sequences) and hydrophilicity profiles of idiotype+ and idiotype- antibodies. We identified four surface-exposed areas (one in the heavy chain and three in the light chain) that may contribute to expression of the idiotope defined by antibody IDA10.

The molecular origin of regulatory idiotypes

A complete immunochemical and molecular profile was generated for a group of hybridoma and myeloma antibodies bearing the A48 regulatory idiotype (RI). These A48 RI+ antibodies were derived from normal or idiotypically manipulated mice and were selected either for utilization of a VHX24 VH gene or expression of the A48 RI. Among the hybridomas selected for VHX24 VH utilization a variety of antibody specificities were seen with the fructosan specificity occurring least frequently and the N-acetylglucosamine specificity occurring most frequently. A variety of Vk families were used with a bias for the Vk1 family by the antibodies deriving from untreated mice. The A48RI was expressed by only 3 of these antibodies, none of which were fructan specific. Two used the canonical VHX24-Vk10 combination utilized by the A48 and UPC 10 prototypes, and one used the VHX24-Vkl combination. This demonstration of A48 RI expression ny non-fructan specific, non-VHX24+Vk10+ antibodies was extended by showing expression of this Id by two monoclonal antibodies specific for the Sm self-antigen, one rheumatoid factor and two monoclonal antibodies specific for influenza virus hemagglutinin molecule. They used different VH-VL combinations. Among the monoclonal antibodies selected for A48 RI expression all exhibited fructan binding activity and the vast majority used the VHX24-Vk10 association. A collective analysis of the VH and VL sequences of all these A48RI+ antibodies showed idiotype expression was not associated with any particular germline VH or VL gene. D, Jk or JH sequence. Three positions on the light chain and one on the heavy chain were identified which could represent the structural correlates for the A48 regulatory idiotype.

A Vh region synthetic peptide induces antibodies which bind native immunoglobulins and augment an immune response to antigen

The BALB/c myeloma protein ABPC48 (A48) binds the polysaccharide bacterial levan; its Vh is encoded by a gene derived from the VhX24 family. This antibody has been shown to cross-react idiotypically with the phosphorylcholine-binding BALB/c myeloma protein MOPC167 whose Vh shares homology with A48 from residues 32-44. We have synthesized a peptide corresponding to residues 32-44 of the Vh encoded by a germline gene of the VhX24 family. Anti-peptide antisera from rabbits were purified by affinity chromatography with peptide or intact antibody. Several myeloma proteins and monoclonal antibodies with varying degrees of homology to the peptide have been analyzed for reactivity with purified rabbit antibodies in solid-phase RIA. We observed that the specificities within rabbit antisera are heterogeneous, and that purification with antibody versus peptide yields preparations containing different specificities, albeit demonstrably peptide-related. We also show that injection of mice at birth with small amounts of purified rabbit antibodies can affect the magnitude of the response to bacterial levan and the expression of A48 idiotopes in that response.

A predominant idiotype independent of specificity, or Ig and H-2 allotypes, is found in the primary but not the secondary murine antibody response to lysozyme

Removal of just the three N-terminal residues Lys-Val-Phe (TIP) on hen egg white lysozyme (HEL), by aminopeptidase cleavage, eliminates an antigenic determinant which is a recurrent and dominant focus of primary but not secondary antibody responses to HEL in a variety of mouse strains. We have generated an anti-idiotypic rabbit antiserum against such a TIP-dependent monoclonal antibody (mAb). This antiserum reacts with many different primary anti-HEL mAb, but fails to react with all of a variety of secondary anti-HEL mAb. The idiotype defined by this antiserum, termed IdXE, is a common feature of early anti-HEL antibody responses but does not appear in secondary responses. Although the presence of IdXE and TIP dependence is correlated in primary responses, studies of idiotype expression on mAb and on plaque-forming cells (PFC) using mixed erythrocyte monolayers clearly show that at the single-cell level the properties are separable, i.e., not all TIP-recognizing PFC display IdXE and a sizable proportion of cells producing non-TIP-dependent antibodies are IdXE+. The restricted idiotypy and specificity of early antibody responses to HEL occur in each of eight diverse mouse strains tested: it is not associated with a particular MHC haplotype, heavy chain allotype or light chain allotype. The finding of such strain-independent restriction in the early response pattern to a typical protein antigen is novel and suggests the involvement of highly conserved, potent regulatory mechanisms which are manifested as a limitation in the initial expression of the available repertoire.

Characterization of a T-cell clone recognizing idiotypes as tumor-associated antigens

Although heterogeneous T cells recognizing idiotypic determinants have been demonstrated to occur spontaneously in vitro or to be expanded by immunization with antigen or idiotype, their in vitro propagation and cloning was not successful. These previous studies have relied extensively on soluble immunoglobulin to induce proliferation of idiotype-specific T cells. This report describes a unique approach to obtain a stable T-cell clone specific for a monoclonal beta 2-6 fructosan binding myeloma ABPC48 (BALB/c origin), bearing well-defined A48 regulatory idiotopes. Following repeated immunizations with ABPC48 myeloma protein of C.B/R3 mice (H-2d, VHb, CHa), which differ only in the VH locus from BALB/c mice (H-2d, VHa CHa), several stable T-cell clones were obtained after stimulation in vitro with ABPC48 myeloma cells. The proliferation of a T-cell clone A48.B2 was observed with irradiated myeloma cells or hybridomas producing antibodies bearing A48 idiotype encoded by genes deriving from the VH 441-4 family. Proliferation of the clone did not occur with soluble ABPC48 myeloma protein or with Sepharose 4B-bound ABPC48 myeloma protein. Both anti-A48Id and anti-Iad monoclonal antibodies can specifically inhibit the proliferation of this clone when stimulated with ABPC48 myeloma cells. These results demonstrate recognition of idiotypes on B-cell tumours by T cells and implicate the role of class II major histocompatibility complex determinants in this cellular interaction.

Biological mimicry of antigenic stimulation: analysis of the in vivo antibody responses induced by monoclonal anti-idiotypic antibodies

In this study, the induction of protective antibodies against a bacterial pathogen in mice was used as a model for idiotype vaccine development. The antibody responses induced in different strains of mice by the hapten phosphorylcholine (PC) coupled to ovalbumin, PC-OVA, were compared with the responses induced by carrier conjugates of two different anti-idiotopic antibodies. One anti-idiotope, 4C11, exhibits the characteristics of an internal image of phosphorylcholine, and therefore is classified as an Ab2 beta; the other, F6, does not mimic antigen, and therefore is classified as an Ab2 alpha. The analysis of the temporal kinetics of the IgM and IgG1 anti-PC responses induced by nominal and idiotope antigens revealed dynamic responses characterized by changes in the quality and quantity of the antibody populations during the course of the immune response. All three antigens could stimulate antibodies that were PC-specific and T15 idiotope-positive in BALB/c and A/St mice. The highest titre of T15+ anti-PC antibodies was achieved with an immunization protocol which involved priming with Ab2 alpha followed by challenge with PC-OVA. Antibodies specific for the extended hapten, diazophenylphosphorylcholine, and hapten-carrier bridge determinants were being stimulated late in the responses to PC-OVA. BALB-c, A/St and CBA/N (Xid) mice all produced, late in the response to Ab2 alpha, high T15+ antibody titres which do not bind PC. The induction of T15+, non-PC binding, antibody suggests that T15 is a regulatory idiotope, expressed on antibodies having differing antigenic specificities. With regard to vaccine development, these results support the contention that effective induction of antibodies does not depend on stimulating a unique idiotope but can be achieved by anti-idiotypes reacting with different idiotopes. In addition, these results suggest that the combined use of idiotope and nominal antigens in an immunization protocol may provide the maximal protective immunity.

Idiotype regulation of self responses, autoantibody V regions and neonatal B cell repertoire

The role of autoantibodies themselves in immune regulation is still unknown. There is evidence that some autoantibody idiotypes (Id) may play a regulatory role in physiologic and possibly pathologic situations of the immune system. Here we present evidence that (1) certain autoantibody Id modulate the immune response to self antigens (regulatory Id), and (2) that the neonatal preimmune repertoire is primarily devoted to self recognition. The humoral and cellular events following immunization with regulatory Id suggest an active participation of T cells in the regulatory events. Based on immunochemical, structural and molecular genetics analysis, it appears that this regulatory Id is of germline origin as it exists within the neonatal preimmune repertoire. B cell hybridomas generated from unstimulated splenocytes of neonatal mice are primarily self-reactive, suggesting that the immune system essentially begins as a self-recognizing system. The findings are discussed with regard to the relationship between germline repertoire, autoantibodies, and regulatory idiotypes.

Interactions between hepatitis B virus and polymeric human albumin. I. Production of monoclonal anti-idiotypes (anti-anti-polymeric human albumin) which recognize hepatitis B virus surface antigen

In an attempt to characterize the polymeric human albumin (polyHSA) receptor expressed on hepatitis B virus and hepatocytes, we have used a human anti-polyHSA IgG to generate monoclonal anti-idiotypes (anti-Id) which bear the internal image of polyHSA and mimic its binding activity. Two monoclonal anti-Id antibodies, 63.14 and 70.F9, were strongly reactive in both radioimmunoassay and enzyme-linked immunosorbent assay (ELISA) with the F(ab')2 of the immunogen as well as with purified hepatitis B surface antigen (HBsAg) expressing various subtypes. The specificity of the binding of anti-Id to HBsAg was confirmed in direct ELISA and by Western blot analysis. These experiments also showed that the anti-Id bind to a site expressed on the major 24-kDa protein of HBsAg particles, and that this recognition is specifically inhibited by polyHSA. Experiments on cellular staining and radioimmunoprecipitation on HBsAg-positive and -negative cell lines showed that the anti-Id recognize intracellular HBsAg but not other liver cell proteins, including the putative polyHSA receptor. These data indicate, therefore, that the monoclonal anti-Id mimic the binding activity of polyHSA and recognize its binding site on the virus. The inability of both anti-Id to react with the hepatocyte surface suggests either the absence of a specific hepatic polyHSA receptor or the expression of one with a different configuration.

Effect of syngeneic anti-idiotypic antibody on influenza virus neuraminidase antibody response

Influenza viruses possess two major surface glycoproteins - hemagglutinin (HA) and neuraminidase (NA). Py203, a monoclonal antibody (Ab) specific for the neuraminidase of the PR8 (H1N1) influenza virus, was used to prepare syngeneic monoclonal anti-idiotypic (anti-Id) Abs. From a BALB/c mouse immunized with Py203 (anti-N1), we obtained RM1, a monoclonal anti-Id Ab. The Py203-Id was detected in a significant fraction of immunoglobulins (Igs) in the primary and secondary responses elicited by PR8 (H1N1) and X31 (H3N2) viruses. In animals injected with minute amounts of RM1 and subsequently boosted with an identical dose of RM1, no detectable anti-NA activity was noted, but a significant increase in Py203-Id-bearing Igs was observed. In the sera of animals injected with minute amounts of RM1 and subsequently boosted with PR8 (H1N1) or X31 (H3N2) viruses, an increase in anti-NA activity and in the level of Py203-Id was noted. Animals injected with large amounts of RM1 and boosted with PR8 and X31 showed a marked suppression of the Py203-Id but no alteration in the anti-NA response. The anti-Id recognizes an idiotope (the Py203 idiotope) shared by antibodies specific for the N1 and N2 neuraminidase variants.

Production, binding characteristics, and immunogenicity of heterologous anti-idiotypic antibody to herpes simplex virus glycoprotein C

A monoclonal antibody specific for glycoprotein C (gC) of herpes simplex virus type 1 (HSV-1) was used to prepare a heterologous anti-idiotypic antibody in rabbits. After absorption with normal mouse immunoglobulin (NMS) the anti-idiotypic (anti-id) antibody retained binding activity for MoAb D4.1, the immunogen. The anti-id (anti-id C) also demonstrated a cross-reactive binding activity, as shown by ELISA, for MoAb D4.2 and MoAb D4.8 which was specific for glycoprotein D (gD) and glycoprotein B (gB) of HSV-1, respectively. Also, anti-id C bound to and eluted from MoAb D4.2 and MoAb D4.8 affinity columns retained the ability to bind all three monoclonal antibodies. This cross-reactive anti-id could inhibit the binding of each of the three monoclonal antibodies to their respective proteins, suggesting an antigen combining site specificity. Subsequently, the idiotope on MoAb D4.8 was shown to be outside the antigen combining site, since anti-id C recognized MoAb D4.8 complexed with gB. The anti-id, however, did not bind MoAb D4.1 or MoAb D4.2, if these monoclonals were bound to gC or gD, respectively, suggesting the cross-reactive determinant was paratopic on those two monoclonals. Immunization of mice with anti-id C could prime splenocytes in vivo to proliferate in response to HSV antigen stimulation in vitro. Thus, spleen cells involved in the HSV immune response in vitro recognized the anti-idiotypic antibody in vivo.

Fine specificity, idiotypy, and nature of cloned heavy-chain variable region genes of murine monoclonal rheumatoid factor antibodies

We investigated the immunochemical and molecular characteristics of murine monoclonal rheumatoid factors. Study of the fine specificity of 20 monoclonal rheumatoid factor antibodies shows a wide degree of heterogeneity. However, many express an interstrain cross-reactive idiotype. We show that our rheumatoid factors utilize a restricted set of the heavy-chain variable region (VH) repertoire representing the more 3' VH families. Preferential expression of 3' VH families is known to occur early in development. We report the nucleotide sequence of two cloned rheumatoid factor VH genes, Y19-10 (VH J558) and 129-48 (VH 7183) in which no major differences are observed between VH genes encoding the heavy chain of autoantibodies and antibodies against foreign antigens.