Antigen-binding, idiotypic T-lymphocyte receptors

Anti-ids in allergy: timeliness of a classic concept

Abstract:

Anti-idiotypic antibodies (anti-ids) are part of natural immune responses with regulatory capacity. Their effect on an antigen-specific, so-called Ab1 antibody response, is dependent on 1) the original antigen, which they mirror, being Ab2 antibodies, and 2) their isotype. In the case of IgE-mediated allergy, natural anti-ids against allergen-specific IgE represent internal images of allergen molecules. A key biologic feature of allergens is that they can crosslink IgE, expressed by B-lymphocytes or passively bound via high affinity receptors to effector cells, which renders cellular activation. Therefore, the IgE cross linking capability of anti-ids determines whether they dampen or enhance immediate-type hypersensitivity. Correspondingly to classic antiallergen blocking IgG antibodies, anti-ids may also interact with inhibitory FcγRIIb receptors and, thereby, down-regulate T_H2-type inflammation. Anti-ids and other B-cell epitope mimetics, like mimotopes and DARPins, represent antigen surrogates, which can be used for vaccination. Intriguingly, they may induce antibody responses without activating potentially proinflammatory, antiallergen T-lymphocytes. Taken together, collective evidence suggests that anti-ids, although representing immunologic classics, are a timeless concept in allergology.

T lymphocytes responding to Mls-locus antigens are Lyt-1+, 2- and I-A restricted

We have investigated primary and secondary responses of mouse splenic T cells to strong mixed lymphocyte stimulating antigens controlled by the Mls locus using MHC-identical mixtures of cells. Our studies show that strong primary Mls-locus specific responses involve recognition of self I-A antigens, since BUdR and light suicide or F1 into parent radiation bone-marrow chimeras both demonstrate a preference of unprimed F1 T cells to respond to Mls-locus antigens associated with one parent's MHC antigens. Furthermore, conventional anti-I-A antisera and monoclonal anti-I-A antibody both inhibit Mls-locus responses in an MHC-specific manner. Finally, as is typical of T cells responding to I-A antigens or to nominal antigens associated with self I-A, Mls-locus responses are mediated by Lyt-1+, 2 cells. One striking finding in these studies was the very high frequency of cells capable of responding to Mls-locus antigens, the highest being 1/300 splenic T cells. This plus evidence for recruitment during primary Mls-locus responses may account for reports of a lack of I-A restriction in secondary anti-Mls locus responses to strong Mls-locus antigens, a finding with which we concur. The possibility that these secondary responses between noncongenic strains of mice may be directed at other genetic loci is also discussed. These experiments leave open the question of the biological role of the Mls-locus and of the very large number of T cells reactive to it.

Activation or suppression of bactericidal activity of macrophages during a graft-versus-host reaction against I-A and I-J-region differences, respectively

Systemic graft-versus-host reactions (GVHR) were induced in F1 heterozygous mice by injecting 10(8) parental lymphocytes. The Anti-Thy 1.2-sensitive, T-cell mediated activation of macrophages was assessed by their increased capacity to destroy a facultative intracellular bacterium Listeria monocytogenes. The difference in MHC regions causing a GVHR that induced high levels of macrophage activation mapped to I-A. In contrast, differences at K or D, in any of the other H-2 subregions or in the non-H-2 background, including Mls alone or in combination, did not induce a GVHR leading to macrophage activation, unless these differences were combined with a difference at I-A. The numbers of parental cells needed to activate macrophages via a GVHR caused by I-A vs. non-I-A differences, varied at least 30- to 100-fold. When parental cells were injected into F1 offspring of parents differing at I-J, growth of Listeria was enhanced significantly; this negative effect on macrophages was not seen when parental combinations differing at I-A alone were compared with those differing at I-A plus I-J or I-J plus other H-2 regions.

The IgG2a/IgA produced by the murine T560 B lymphoma that arose during a graft-versus-host reaction is polyreactive and somatically mutated

In mice undergoing a graft-versus-host (GVH) reaction, donor T cells responding to the host's MHC antigens induce polyclonal activation of the host's B cells and secretion of their antibodies and autoantibodies. T560, a CD5- B lymphoma that arose in the gut-associated lymphoid tissue (GALT) of a (B10 x B10.H2aH4(b)pWts) F1 hybrid mouse that had been injected with parental B10.H2aH4b splenocytes, is of particular interest because it produces switched, heavily mutated, but, nevertheless, polyreactive immunoglobulin. T560 bears and contains IgG2a but switches to IgA spontaneously. The T560 Ig variable region is encoded by a V186.2-related VH gene, juxtaposed to DFL 16 and J(H)1, and by a Vkappa gene of the Vkappa 4/5 group juxtaposed to Jkappa1. Both VH and VK are heavily mutated. The IgA binds to polystyrene, to p-azophenyl-phosphorylcholine (PC)-conjugated keyhole limpet hemocyanin (KLH) (PC-KLH), to 2,4,6 trinitrophenylated (TNP)-KLH and to human TNF-beta but not to KLH, human TNF-alpha, or any of several other Ags tested. Hapten inhibition experiments indicate that the polystyrene, PC- and TNP-binding sites do not overlap. The switched isotypes and heavy load of somatic mutations found in the T560 IgG2a/IgA suggest that T cell-dependant somatic selection of the T560 precursor B cell may have been superimposed on polyclonal B cell activation originally associated with the GVH.

Role of repetitive antigen patterns for induction of antibodies against antibodies

Antibody responses against antibodies, such as rheumatoid factors, are found in several immunopathological diseases and may play a role in disease pathogenesis. Experience shows that they are usually difficult to induce experimentally. Antibodies specific for immunoglobulin constant regions (anti-allotypic) or for variable regions (anti-idiotypic) have been investigated in animal models; the latter have even been postulated to regulate antibody and T cell responses via network-like interactions. Why and how such anti-antibodies are induced during autoimmune diseases, has remained largely unclear. Because repetitively arranged epitopes in a paracrystalline structure of a viral envelope cross-link B cell receptors efficiently to induce a prompt T-independent IgM response, this study used immune complexes containing viruses or bacteria to evaluate the role of antigen pattern for induction of anti-antibody responses. We present evidence that antibodies bound to strictly ordered, but not to irregularly arranged, antigens dramatically enhance induction of anti-antibodies, already after a single immunization and without using adjuvants. The results indicate a novel link between anti-antibody responses and infectious agents, and suggest a similar role for repetitive self-antigens such as DNA or collagen involved in chronic immunopathological diseases.

Genetic control of contact photosensitivity to tetrachlorosalicylanilide. II. Igh complex controls the sensitivity induced by photohapten-modified spleen cells but not epidermal cells

We studied the genetic control of murine contact photosensitivity (CPS)1 to 3,3',4',5-tetrachlorosalicylanilide (TCSA) that was induced by subcutaneous injection of TCSA-photomodified epidermal cells (photoTCSA-EC) and spleen cells (photoTCSA-SC). With regard to the H-2 locus, sensitization with both types of photohaptenated cells showed the same pattern of CPS responses: H-2k and H-2b,d haplotypes were closely associated with low and high responders, respectively. On the other hand, the Igh locus affected the CPS reaction induced by photoTCSA-SC but not -EC; the Igh-1d allotype was related to low responsiveness, while high responders possessed Igh-1a,b. Thus, the photoTCSA-SC sensitization was controlled by H-2 and Igh in a codominant manner. The photoTCSA-SC-induced responses of H-2k but not Igh-1d mice were enhanced by CY pretreatment, suggesting that the mechanisms of low responsiveness in H-2k and Igh-1d mice were different. H-2 identity between donors of photoTCSA-EC and recipients was sufficient for effective sensitization, whereas both H-2 and Igh between donors of photoTCSA-SC and recipients should be identical to obtain maximum sensitization. This further confirmed the involvement of the Igh complex in the genetic control of CPS evoked by photoTCSA-SC. B cells as well as macrophages served as an effective presentation template for the photoTCSA-SC sensitization in the high responder Igh-1a mice, whereas B cells failed in inducing the CPS reaction in the low responder Igh-1d mice. These results suggest that B cells play an essential role in the Igh control phenomenon seen in the photoTCSA-SC sensitization. The present study demonstrated that CPS induced by photohapten-modified cells are differentially regulated by the H-2 and Igh gene loci depending on the cell type used for sensitization.

Epitope- and antigen-specific cancer vaccines

Anti-idiotypic antibodies (Ab2) that functionally mimic epitopes associated with human cancer cells are the most specific cancer vaccines currently available. Ab2 can induce specific humoral anti-tumor immunity in cancer patients. However, the potential of Ab2 for inducing cellular immunity in cancer patients still requires demonstration. Clonotypic antibodies directed against the combining site for tumor Ag on human T-cell clones may provide highly effective reagents for inducing protective T-cell immunity against human cancer. A new generation of cancer vaccines, molecularly cloned tumor-associated antigens (Ag), has recently been developed. Recombinant Ag have been successfully expressed in vectors allowing large scale production of Ag for immunization of cancer patients. Recombinant tumor Ag was shown to induce specific and protective immunity in experimental animals. In contrast to Ab2, which may mimic a single cancer-associated epitope, recombinant Ag express multiple epitopes that are potentially immunogenic. Ag vaccines, therefore, may be more effective in arresting tumor growth than single epitope (Ab2) vaccines because tumor destruction by antibodies is dependent on antibody density on tumor cell surfaces. In light of the important roles that both B and T cells play in the control of tumor growth, the demonstration of induction of specific B and T cell-immunity by recombinant tumor Ag and Ab2 in experimental animals is encouraging. Ultimately, the immunomodulatory role of both types of vaccines has to be compared in cancer patients who are immunologically tolerant to many Ag/epitopes expressed by their growing tumors. The development of both Ab2 and recombinant Ag for single antigenic systems provides the first step towards this goal.

Ultraviolet-induced suppressor T cells and factor(s) in murine contact photosensitivity. II. Igh-V restriction of T-cell-suppressor factor

In murine contact photosensitivity (CPS) to 3,3',4',5-tetrachlorosalicylanilide, we have reported that antigen-specific suppressor T cells and factor(s) (TsF) are induced by preexposure of the photosensitizing site to low doses of ultraviolet B. The TsF is a single-chain factor bearing both antigen-binding site(s) and I-J determinants. In this report, we examined the genetic restriction of the factor in terms of both H-2 and Igh-associated genes. The CPS responses of BALB/c (H-2d, Igh-VaCa) and BALB.B (H-2b, Igh-VaCa) but not DBA/2 (H-2d, Igh-VcCc) were suppressed by the injection of the BALB/c TsF, and reciprocally, the response of BALB/c was suppressed by the BALB.B TsF. This demonstrated that H-2 identity was not a requirement for TsF function. Furthermore, the BALB/c TsF significantly suppressed the CPS reaction in BAB-14 (H-2d, Igh-VaCb) but not in either C.B-20 (H-2d, Igh-VbCb) or C.AL-20 (H-2d, Igh-VdCd). In addition, the BAB-14 TsF, but not the C.B-20 factor, induced suppression in BALB/c mice. These results indicated that identity at the Igh-V locus of the strain producing the factor and the recipient was required for suppression. Because of the single-chain nature of the factor, it seems that the I-J+ molecule present in our TsF is closely related to not only recognition but also Igh-V restriction functions.

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.

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.

Idiotypic analysis of anti-I-Ak monoclonal antibodies. III. T- and B-cell responses to anti-Ia idiotopes are not modulated by syngeneic anti-idiotypic monoclonal antibodies

To investigate whether anti-idiotypic (anti-Id) antibodies activate T cells either directly or indirectly, we examined the ability of syngeneic anti-Id monoclonal antibodies (mAbs) to regulate idiotype (Id) expression, antigen-binding antibody production, and T-cell reactivity to antigen. Our idiotypic system consists of an anti-I-A mAb that carries an infrequently expressed Id. Using three syngeneic anti-Id mAbs (Ab2), we previously defined the idiotype of the 11-5.2.1.9 (11-5) anti-I-Ak mAb. Two of these mAbs, IIID1 and IA2, recognize the same or closely related epitopes on 11-5 and cross react with two additional anti-I-Ak mAbs, 8B and 39J; the third anti-Id mAb, VC6, recognizes a distinct epitope shared by 11-5 and 8B. In the present study, BALB/c (H-2d) mice were primed with varying doses of these anti-Ids and were then boosted with C3H (H-2k) spleen cells. Among 130 such primed mice, the syngeneic anti-Ids when tested at priming doses between 10 ng and 10 micrograms were unable to induce Id production. The priming anti-Id mAbs persisted in the serum of the mice and were detectable as late as 40 days after priming. Ab1 expression was not modulated in BALB/c mice immunized with KLH-coupled Ab2, however, this immunization elicited the production of Ab3 which shared idiotypes with 11-5, 8B, and 39J. BALB/c anti-C3H alloreactive T-cell clones were also not induced by anti-Id priming, nor could they be shown to bind directly to the three Ab2 used. Nevertheless, the proliferative response of one anti-I-Ak specific T-cell clone that recognizes the same epitope as 11-5, 8B, and 39J, was inhibited by the IIID1 and IA2 Ab2. Thus, a T cell can express an idiotype shared by a B cell, but the linked recognition of an Id-associated carrier determinant(s) by an alloreactive T cell is required to elicit an anti-Id antibody response. These results favor the possibility that the activation of T cells is not dependent upon their ability to bind to anti-Id, but rather on their capacity to respond to epitopes of Id-anti-Id antigen-antibody complexes formed on B cells.

Studies of monoclonal antibodies specific for major histocompatibility complex products of the rat. III. Production and characterization of syngeneic and allogeneic monoclonal anti-idiotypic antibodies to monoclonal alloantibodies

Sixteen monoclonal anti-idiotypic antibodies were prepared against RT1 antigen-specific monoclonal antibodies by means of an inhibition assay. Three (110-3, 112-89, and 133-4) were produced against antibody 3-8C2 (19), three (178-60, 181-14, and 184-38) against antibody 11/23/5, and three (144-3, 144-33, and 146-31) against antibody 1-5A4. One monoclonal anti-idiotypic antibody (21-39) was directed against antibody 1-8D2 and six (CE1-3, CE2-1, CE7-2, CE8-46, CE9-35, and CE10-2) against antibody 3-12A1. The anti-idiotypic antibodies were all highly specific for the respective monoclonal antibody used for the induction of the anti-idiotype and did not cross-react with other monoclonal antibodies.

Antigenic properties of T cell antigen-specific receptors isolated from the surface of rabbit and mouse spleen and lymph node cells

The presence of a allotypic determinants was tested in fractions obtained by gel filtration of antigen-specific receptors isolated by immunoadsorption from lymphoid cells of antigen-stimulated a3-3 rabbits. This technique, as well as the inhibition of the reaction of isolated receptors with anti-T cell receptor antisera (anti R) by anti-a3 antibodies failed to demonstrate the presence of a allotypic determinants. The inhibitory effect of antigen-specific receptors isolated from the lymphoid cells of stimulated A/J mice on the cytotoxic effect of anti-Ia antibodies on mouse spleen cells in the presence of rabbit complement was tested. All preparations inhibited the cytotoxic reaction with the average effectivity of 60%. In order to confirm the presence of Ia determinants on the rabbit and mouse T cell receptor molecules it was shown that the reactions of three anti-R antisera with 12 different receptor preparations were inhibited by anti-Ia antibodies. SDS-PAGE analyses of 125I-labelled mouse specific receptors and the precipitate obtained by anti-R antisera showed that T cell receptors were present in fractions with molar mass 100 and 85 kg/mol. The molar mass of the former fraction after reduction and alkylation was 45 kg/mol.

Studies of monoclonal antibodies specific for major histocompatibility complex products of the rat. I. Production and characterization of monoclonal antibodies

Sixteen monoclonal antibodies against antigens coded for by the RT1 complex of the rat have been produced. Fourteen are specific for the a haplotype: six recognize class II and eight class I antigens. Two are specific for the 1 haplotype, one reacting with class I and the other with class II antigens. By means of these monoclonal antibodies four independent clusters of antigens for class I antigens of the a haplotype and three for class II antigens could be defined. The three antigenic sites of class II antigens reside on the same heterodimer. The monoclonals described here are characterized with regard to Ig class and subclass, pI, and complement-activating capacity.

Studies of monoclonal antibodies specific for major histocompatibility complex products of the rat. II. Production and characterization of xenogeneic, allogeneic, and syngeneic polyclonal anti-idiotypic antibodies

Polyclonal anti-idiotypic antibodies against monoclonal antibodies with specificity for RT1-encoded antigens were induced in syngeneic, allogeneic, and xenogeneic hosts. The immune response to the idiotypic determinants on monoclonal antibodies was T-cell-dependent. The anti-idiotypic antibodies, independent of whether they were induced in syngeneic, allogeneic, or xenogeneic (after proper absorption) hosts, showed an exquisite specificity for the monoclonal antibody used for the induction. No cross-reactivity with other monoclonal antibodies could be observed.

Surface expression and partial characterization of an arsonate hapten-specific idiotype-bearing T-cell receptor

Anti-idiotype antibodies raised against the arsonate hapten idiotype have been used to detect arsonate-binding receptors on the surface of peripheral T cells of A/J mice and to isolate this material after biosynthetic labeling for partial chemical characterization. It was found that 2-3% of splenic T cells from arsonate-immune mice specifically bound the hapten using immunofluorescent keyhole limpet hemocyanin as a carrier. In double-immunofluorescence labeling experiments, a high proportion (approximately equal to 70%) of these cells also bound the (Fab')2 fragment of rabbit anti-idiotype antibody in exactly the same patches on the cell as the arsonate hemocyanin antigen. In addition, the anti-idiotype antibody inhibited the binding of the hapten-carrier complex to T cells by approximately equal to 70%. In parallel experiments, fowl antibodies against mouse (Fab')2 fragments bound to 100% of arsonate-binding T cells in the same cell-surface patches as the hapten, and were capable of inhibiting 100% of the hapten-binding cells. Capping, shedding, and resynthesis experiments indicated that the T cells synthesized their antigen-binding idiotype-bearing receptors. Immunoblots of unreduced detergent extracts of purified splenic T cells developed with anti-idiotype antibodies showed bands at 150,000 and 94,000 Da. Equal amounts of protein extracted from liver and analyzed in the same gels as the T-cell material failed to show any reactivity with anti-idiotype antibodies. To confirm the biosynthetic origin of the idiotype-positive materials, detergent extracts from 75Se-methionine- or [3H]leucine-labeled Con A-treated splenic T cells were reacted with anti-idiotype antibodies and the bound material was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the presence of 2-mercaptoethanol the major band was at 68,000 Da, with variable minor levels of material at 45,000 Da, while when hapten was used to isolate the receptor a dominant 25,000- to 30,000-Da band was seen. We believe that the higher-molecular-weight materials are multimers of the 25,000-30,000 subunit.

Analysis and modulation of the immune response of mice to acetylcholine receptor by anti-idiotypes

Anti-idiotypes were raised in mice against three well-characterized anti-acetylcholine receptor (AChR) monoclonal antibodies (mcAbs), as well as against polyclonal mouse anti-AChR antibodies. In binding experiments, the anti-idiotypic antibodies inhibited the binding of AChR only to the immunizing idiotype. However, a less restricted specificity was found in in vivo experiments. Mice producing anti-idiotypes were challenged with AChR and the idiotypic composition of their anti-AChR response was analysed using specific rabbit anti-idiotypic antibodies. It was found that preimmunization with a certain idiotype leads to the preferential suppression of this particular idiotype in the polyclonal response to AChR. However, preimmunization with either polyclonal or monoclonal anti-AChR antibodies resulted in a reduction of the overall anti-Torpedo AChR and anti-muscle AChR titers. This reduction was greater than would be expected from the representation of each of the respective idiotypes in the polyclonal anti-AChR serum, and may imply that in addition to the immunizing idiotype other anti-AChR idiotypes are also suppressed. Our results suggest that anti-idiotypes may have a potential for the modulation of the autoimmune response directed against AChR in myasthenia.

Establishment and biological activity of a proliferative anti-idiotype-activated T cell line

Antisera were raised in rabbits against a monoclonal antibody (McAb 103) of C3H.SW origin which is specific to the synthetic polypeptide (T,G)-A-L and was shown to express the major idiotypic determinants of conventional anti-(T,G)-A-L antibodies. Antibodies were purified and were shown in a binding assay to recognize McAb 103 as well as C3H.SW anti-(T,G)-A-L antibodies. C57BL/6 mice were immunized with the purified rabbit anti-McAb 103 (Ra 103) and their lymph nodes were studied in a proliferation assay. Proliferation was observed in the presence of both Ra 103 and (T,G)-A-L, although the latter stimulated the cells to a lesser extent, suggesting the induction in vivo of (T,G)-A-L-specific clones in low frequency. A T cell line was established from these lymph node cells. The line is kept in continuous growth in the presence of IL-2 and periodic triggering with Ra 103. A significant proliferative response was obtained with Ra 103 only. This proliferation could be almost completely inhibited by either McAb 103 or by conventional anti-(T,G)-A-L antibodies of C3H.SW origin, indicating the cross reaction between the idiotypes expressed on the T cell line and the (T,G)-A-L-specific antibodies. No proliferation could be detected in the presence of either normal rabbit IgG or rabbit anti-mouse IgG. Thus, the T cell line TId 103 allows the analysis of the role of idiotype in T cell recognition and regulation.

Cytotoxic T cell clone-specific monoclonal antibodies used to select clonotypic antigen-specific cytotoxic T cells

Two rat monoclonal antibodies (mAb) have been produced which recognize a clone-specific determinant on the alloreactive cytotoxic T lymphocyte (CTL) clone 3 F9. CTL clone 3F9 of BALB/c origin is specific for H-2Db and can be grown by weekly restimulation with irradiated stimulator spleen cells expressing H-2Db in the presence of interleukin 2. Two mAb against T cell clone 3F9, 44-22-1(IgG2a) and 46-6 B5(IgM), have been proven to be clone specific: they inhibit cytotoxic activity of 3F9 only and bind specifically to 3 F9 when compared in a panel of different CTL clones, or cells from different mixed lymphocyte cultures (MLC), BALB/c thymus and spleen cells. The mAb 44-22-1 has been used to sort cells from a primary MLC BALB/c anti-H-2Db by fluorescence-activated cell sorter (FACS) to select CTL expressing 3 F9 clonotype-specific determinants. The lymphocytes reactive with 44-22-1 represent a minor subpopulation of the CTL of the primary MLC. The specific alloreactive cytotoxicity of unsorted lymphocytes of the bulk primary MLC could not be inhibited by the mAb 44-22-1 and 46-6 B5 whereas the sorted 3 F9 clonotype-positive cultures could be inhibited very effectively. All the CTL clones derived from the FACS-sorted clonotype-positive culture show all the same properties and are identical with clone 3 F9 with respect to antigen-specific cytotoxicity, inhibition of cytotoxicity by the mAb and surface markers.

Correlation between immunosuppressive activity and translation regulatory activity

An immunoglobulin negative material from the eluate of an anti-idiotype immunosorbent column [1] exhibited potent immunosuppressive activity. This material also inhibited the translation of globin mRNA in a cell-free reticulocyte lysate system. The translation inhibitory activity of this material was not attributable to nucleases which were separable by a blue-dextran agarose column. Further correlation between immunosuppressive activity and translation inhibitory activity was observed when GTP or GTP analogue was included in experimental systems. These results suggest that the immunosuppressive factor (or factors) may contain a translation inhibitory factor. The biochemical mechanism of immunosuppression is discussed.

Photoaffinity-labeled hapten-binding T-cell receptor on a suppressor T-cell hybridoma

A T-cell hydridoma, 7C3-13-Ag6, which produces a (4-hydroxy-3-nitrophenyl)acetyl (NP)-specific suppressor T-cell factor associated with an I-J determinant, was utilized to study the hapten-binding receptor of T-cells. This hybridoma had been shown to express NP-binding receptor molecules on the cell surface with heteroclitic fine specificity for a cross-reactive hapten, (4-hydroxy-5-iodo-3-nitrophenyl) acetyl (NIP). The stoichiometric analysis of the hapten binding by 7C3-13-Ag6 cells was performed by the measurement of direct binding of highly radioactive haptens to the cell surface. The affinity constant (Ka) of the receptor for N125IP-epsilon-aminocaproic acid (N125IP-cap), as calculated from a Hill plot, was 5.75 X 10(7) M-1 [Hill coefficient (a) = 0.86; expression of receptor sites per cell = approximately 1 X 10(3) on average]. The receptor molecule was specifically affinity labeled with photoreactive nitroaryl azide derivatives of N125IP (510-570 Ci/mmole). The specificity of photoaffinity labeling was demonstrated both by competitive inhibition of labeling with NIP- or NP-cap and by differential photoaffinity labeling based on the reversibility of hapten-receptor interaction. The gel electrophoretic analysis of the photoaffinity-labeled molecule indicated that the hapten-binding receptor of 7C3-13-Ag6 has a mol. wt of 28,000 +/- 3000 and an isoelectric point of 5.6-5.7. No immunoglobulin determinants were detected on the molecule. A comparative immunoprecipitation analysis of the membrane lysate of 7C3-13-Ag6 with monoclonal anti-I-J reagents identified a separate I-J molecule of 25,000 +/- 1000 mol. wt that is distinct from the photoaffinity-labeled hapten-binding molecule.

Poly(Glu60,Ala30,Tyr10) (GAT)-specific T cells do not express B cell public idiotopes but can be primed by monoclonal anti-idiotypic antibodies

Eight monoclonal anti-idiotypic antibodies directed against public idiotopes have been further characterized: (a) they bind to public idiotopes with a high affinity; (b) they recognize all anti-poly(Glu60,Ala30,Tyr10) (GAT) antibodies as measured by inhibition of the anti-GAT plaque-forming cell response. This has been verified in three strains of mice. These reagents were not able to detect idiotope expression on eight GAT-specific helper T cell lines and clones. This result was obtained by two techniques: (a) idiotope expression at the T cell surface was measured by indirect immunofluorescence using a cell sorter with surface antigens H-2D, Thy-1.2, Lyt-1 and L3T4 as positive controls; (b) after immunoadsorption of [35S] methionine-labeled cellular extracts from two lines, no unique molecule was retained by the HP-idp22 monoclonal anti-idiotypic antibody coupled to Sepharose. Despite these negative results, this antibody was found to prime lymph node cells in vivo, which were able to proliferate specifically in response to GAT. Two T cell lines derived from this lymphocyte population do not express any of the idiotopes tested. These results suggest that monoclonal anti-idiotypic antibodies may be influencing T lymphocyte activity indirectly.

Immunological surveillance of tumors in the context of major histocompatibility complex restriction of T cell function

The immunological surveillance hypothesis was formulated prior to the realization of the fact that an individual's effector T cells generally only see neoantigen if it is appropriately presented in the context of self MHC glycoproteins. The biological consequence of this mechanism is that T lymphocytes are focused onto modified cell-surface rather than onto free antigen. The discovery of MHC-restricted T cell recognition, and the realization that T cell-mediated immunity is of prime importance in promoting recovery from infectious processes, has thus changed the whole emphasis of the surveillance argument. Though the immunological surveillance hypothesis generated considerable discussion and many good experiments, there is no point in continuing the debate in the intellectual context that seemed reasonable in 1970. It is now much more sensible to think of "natural surveillance" and "T cell surveillance," without excluding the probability that these two systems have elements in common. We can now see that T cell surveillance probably operates well in some situations, but is quite ineffective in many others. Part of the reason for this may be that the host response selects tumor clones that are modified so as to be no longer recognized by cytotoxic T cells. The possibility that this reflects changes in MHC phenotype has been investigated, and found to be the case, for some experimental tumors. In this regard, it is worth remembering that many "mutations" in MHC genes that completely change the spectrum of T cell recognition are serologically silent. The availability of molecular probes for investigating the status of MHC genes in tumor cells, together with the capacity to develop cloned T cell lines, monoclonal antibodies to putative tumor antigens, and cell lines transfected with genes coding for these molecules, indicates how T cell surveillance may profitably be explored further in both experimental and human situations.

Anti-idiotypic antibodies and autoantibodies

In this paper, we have provided experimental evidence that antibodies to autoantigens bear common idiotypes and that this property makes them susceptible to anti-idiotypic regulation. Spontaneously occurring autoantibodies to Tg in rats have been extensively investigated as a model of immune response responsible for the appearance of autoimmune disease. Large idiotypic cross-reactivity was found among autoantibodies of various individual animals. Similarly, a high degree of idiotypic relatedness was found among mouse monoclonal antibodies reacting with a highly conserved antigenic domain of thyroglobulin. Both rat and mice idiotype were found to be present on spontaneous and induced antibodies to rat thyroglobulin from individuals of other species. In vivo experiments showed that anti-idiotypic antibodies can be effective in suppressing autoantibodies formation. In the induced TIN in BN rats, a single injection of anti-idiotypic serum prior to the induction of autoimmune disease was sufficient to generate a significant selective suppression of autoantibodies produced against a pathogenetic chemical form of the autoantigen, that is, the one against which the autoantibodies used to prepare the anti-idiotypic reagent as mostly reactive. Similarly, it was found that repeated injections of anti-idiotype into rats with ongoing spontaneous production of autoantibodies to thyroglobulin were able to significantly decrease the amount of circulating autoantibodies from the pretreatment values. Thus, although the beneficial effect of anti-idiotype observed in these experiments was only partial, indications were obtained that a specific anti-idiotypic immunity can be used to regulate autoantibody production. Finally, evidence has been provided to support the hypothesis that auto-anti-idiotype, as a normal constituent of the immune response, can be responsible for the potentiation of immune complex-mediated tissue injury that is often the hallmark of autoimmune diseases.

T-cell hybridoma specific for a cytochrome c peptide: specific antigen binding and interleukin 2 production

T-cell hybridomas were obtained after fusion of BW 5147 thymoma and long-term cultured T cells specific for cytochrome c peptide 66-80 derivatized with a 2,4-dinitroaminophenyl (DNAP) group. The resulting hybridomas were selected for their capacity to specifically bind to soluble radiolabeled peptide antigen. One T-cell hybrid was positive for antigen binding. This hybrid T cell exhibits surface phenotypic markers of the parent antigen-specific T cells. The binding could be inhibited either by an excess of unlabeled homologous antigen or by cytochrome c peptide 11-25 derivatized with a 2-nitrophenylsulfenyl group. Several other peptide antigens tested failed to inhibit binding of the radioactive peptide. This suggests that a specific amino acid sequence, modified by a DNAP group, is the antigenic structure recognized by the putative T-cell receptor. In addition, direct interaction of DNAP-66-80 peptide with the hybridoma cell line induced production of the T-cell growth factor interleukin 2. Furthermore, supernatants derived from syngeneic macrophages pulsed with the relevant peptide also induced the antigen-specific hybridoma to produce interleukin 2.

Three T cell hybridomas do not contain detectable heavy chain variable gene transcripts

We attempted to determine whether T cells express any VH gene segments. cDNA libraries were constructed from one suppressor and two helper T cell hybridomas. Both the library construction and screening were designed to maximize detection of a wide range of VH gene segments. One screening method should detect about half of the sequenced VH genes, while the second should detect most of these genes. The probability of detecting a VH gene homologous to the probes and present at 10 copies per cell was 77% for one helper cell cDNA library, 88% for the second helper cell library, and greater than 99% for the suppressor cell library. No cDNA clones with VH gene segments were detected. From this result, we conclude that VH gene segments are not likely to encode the antigen-specific receptor in the cells we tested.

Monoclonal anti-VH antibodies recognize a common VH determinant expressed on immunoglobulin heavy chains from various species

Our previous work using rabbit antibodies to the variable region of MOPC315 myeloma heavy chain (VH) has indicated the existence of framework determinant(s) common to many murine heavy chains. Here we report the characterization of anti-VH monoclonal antibodies (mAb) prepared in an attempt to elucidate the nature of the common VH determinant. We immunized AKR/J mice with a purified VH315 fragment and generated somatic cell hybrids by the fusion of the immune AKR/J splenocytes with the NS1 myeloma cells. Thirty-seven common anti-VH and 57 subgroup VHI-specific hybridomas have been established and characterized. Whereas the anti-subgroup mAb seemed to react with a determinant unique to the MOPC315 (mouse VHI) subgroup, all the anti-VH mAb reacted with myeloma heavy chains of different VH subgroups, class and allotypes. Antibody competition studies revealed that the VH subgroup determinants are distinct from the common VH determinants and that both were also recognized by the rabbit polyclonal antibodies. The common VH determinants were found to be "hidden" determinants on intact immunoglobulin molecules being exposed only on isolated heavy chains. Furthermore, they are sequential determinants since they are preserved on fully denatured heavy chains. The common VH determinants are shared by immunoglobulins of a wide range of vertebrates from amphibia to man and thus represent antigenic structures which were highly conserved throughout evolution.

Quantitative of anti-NP (4-hydroxy-3-nitrophenyl)-acetyl idiotype expression on spleen and thymus cells

Direct binding of 125I-labeled rabbit anti-NPb idiotype antibodies (RaId) was used to quantitate the expression by immune spleen and thymus cells of NPbId, the characteristic Id of the lambda 1-containing antibodies made by C57BL/6 (B6) mice to the (4-hydroxy-3-nitrophenyl)acetyl (NP) group. Direct binding of RaId by B and T cell preparations reached a maximum of 12 ng RaId per 10(8) cells at 7 days after immunization. Spleen T cell preparations maintained similar levels of binding after positive selection for Thy-1.2+ cells and overnight culture. RaId binding was also demonstrated for immune B6 thymus cells and for spleen and thymus cells of immune SJL mice, which have the appropriate heavy chain allotype for NPbId expression but have only barely detectable serum Id. However, the NPbId of T and B cell preparations were indistinguishable by (a) the susceptibility of RaId binding by the cells to inhibition by hapten or by antibodies to the variable regions of lambda light chains (anti-V lambda) and by (b) the ability of anti-V lambda and of monoclonal antibodies to the constant region of lambda 1 chains (anti-C lambda 1) to immunoprecipitate antigen (NP10-bovine serum albumin)-binding proteins from detergent extracts of isotopically labeled cells. The results strongly imply that virtually all of the NPbId of T cell preparations is due to conventional NPbId antibody that is tightly bound to T cells. The results do not, however, exclude the possibility that the T cell preparations contain a trace amount (less than or equal to 1 ng/10(8) cells) of unusual NPbId-like molecules that lack lambda chains.

T-cell antigen receptors: fact and artefact

Much has been written to support the view that T-cell antigen-recognition molecules share idiotypes with immunoglobulin and are encoded in the same VH genes. Here Jacques Miller and his colleagues disbute this view and argue instead, from recent evidence, that the genes for T-cell receptors are entirely different from Ig genes.

Antiidiotypes against anti-H-2 monoclonal antibodies. V. In vivo antiidiotype treatment induces idiotype-specific helper T cells

Mice have been treated in vivo with xenogeneic antiidiotypes prepared against a murine monoclonal anti-H-2Kk antibody, 11-4.1. B cell immune responses have been found to be altered by such treatment as evidenced by a modification in the idiotypic repertoire of the humoral response to H-2 antigens. Transfer of purified T cells into nude mice before anti-idiotype treatment showed that T cells are involved in the induction of idiotope-bearing antibodies by xenogeneic antiidiotype. Studies using bone marrow chimeras indicate that the environment in which either T or B cells mature does not appear to alter VH region genetic control of induction of antiidiotype-induced molecules. By adoptive transfer studies, T cells from antiidiotype-treated mice were found capable of modifying the idiotypic repertoire of B cells subsequently exposed to antigen even when the T cells were obtained from antiidiotype-primed mice of inappropriate allotype. Although it still must be determined whether idiotypic or antiidiotypic T cells are involved in such B cell idiotype regulation, these results indicate that some T cell functions are altered by xenogeneic antiidiotypes prepared against B cell products and suggest that T cell immunity to major histocompatibility complex antigens may also be affected by such reagents.

A T15-idiotype-positive T suppressor hybridoma does not use the T15 VH gene segment

The T suppressive factor (TsF) released from a T15-idiotype-positive phosphocholine (PCho)-specific T hybridoma, F18-3-4, which was formed by fusion between BALB/c T cells and BW5147 thymoma, was immunochemically characterized. TsF inhibited the in vitro induction of both IgE and IgG1 antibody responses of 2,4-dinitrophenyl keyhole limpet hemocyanin (DNP-KLH)-primed spleen cells in the presence of PCho-KLH-DNP. TsF had the ability to bind to PCho determinants and possessed T15 idiotype determinants as well as Iad products. However, we were unable to detect either the rearrangement of the T15 VH gene or the presence of T15 VH gene transcripts in hybridomas by DNA and RNA blot hybridization analyses with the T15 VH DNA probe.

Immunoglobulin VH determinants defined by monoclonal antibodies

Hybridoma clones secreting antibodies against common VH determinants were readily produced by fusion of cells from mice immunized with isolated V mu fragments of human immunoglobulins (Ig), but not with intact Ig molecules or isolated heavy chains. Four monoclonal antibodies to the V mu fragments of different IgM paraproteins were selected for analysis: MH-44 (mu kappa), GB-24 (mu kappa), NF-11 (gamma 1 kappa), and SA-44 (gamma 1 kappa). Each antibody reacted with the homologous V mu fragment, homologous mu chain, and normal gamma chains, but not with the intact IgM molecules, intact IgG, or isolated light chains, as determined by radioimmunoassay. The VH reaction spectra with a panel of myeloma heavy chains showed overlapping but distinctive patterns for the four antibodies. Each of the four monoclonal anti-VH antibodies appeared to react with a different "hidden" VH determinant that is not exposed on undenatured, intact Ig molecules and differs from conventional VH subgroup determinants. In immunofluorescence studies, the monoclonal anti-VH antibodies did not bind to surface Ig on viable B lymphocytes, but visibly stained subpopulations of fixed B lymphocytes, pre-B cells, and normal plasma cells. The mean frequencies of VH+ plasma cells were 30% (MH-44), 17% (GB-24), 13% (NF-11), and 3% (SA-44), and similar frequencies were obtained for the VH+ B cell subpopulations. While subpopulations of B cells could be identified at all stages in differentiation by immunofluorescence with the anti-VH antibodies, neither resting nor activated T cells expressed these VH determinants in detectable amounts.