Antigen receptors of T helper cells

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.

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.

A common idiotope on T cell receptors and antibodies expressed in the absence of network selection

The monoclonal antibody F6(51), directed to an idiotope of MOPC 460-like anti-1,4,6-trinitrophenl (TNP) antibodies produced in IgHa mouse strains, identifies in helper T cells from C57BL/6 (IgHb) mice with (4-hydroxy-3-nitrophenyl)acetyl (NP)-self specificity, a clonotypic determinant functionally and biochemically associated with the specific T cell receptor. The expression of this antibody-related T cell clonotype in C57BL/6 mice, although "recurrent", is independent of network selection, as shown by its presence in B mice suppressed from birth with anti-mu antibodies, and in IgH-congenic mouse strains. These results indicate aleatory cross-reactivity between T cell receptors and antibodies and command caution in network interpretations for "idiotype sharing".

Turning (Ir gene) low responders into high responders by antibody manipulation of the developing immune system

The ability of helper T cells directed against trinitrophenyl-modified syngeneic spleen cells to recognize low-hapten densities on target cells is under major histocompatibility complex-linked Ir gene control. Thus, BALB/c (H-2d) mice are low responders while H-2 congenic BALB.C3H (H-2k) mice are high responders. Immunization of adult BALB/c mice with the monoclonal antibody F6(51), directed to shared idiotopes by anti-trinitrophenyl antibodies and clonal receptors on anti-trinitrophenyl-self helper T cells, leads to the production of high titers of circulating idiotype, has no influence on helper T cell idiotypic profiles, but shifts to a high-responder phenotype the ability of helper T cells to recognize low-hapten densities. These effects on Ir gene phenotype are even more striking in untreated progenies from F6(51)-immunized BALB/c females, which are better responders than genetically high-responder BALB.C3H mice, although completely different in the expression of the F6(51)-defined clonotype. The general significance of these findings on Ir gene-directed T-cell repertoire selection is discussed, for they constitute formal evidence against antigen-presentation as a mechanism of Ir gene effects and strong support for the importance of maternal influences on the development of T-cell repertoires.

T cell activation by anti-idiotypic antibody: mechanism of interaction with antigen-reactive T cells

It has been shown that the activation of T cells by an anti-idiotypic antibody (anti-Id) TB71 containing an internal image of the corresponding mycobacterial antigen (38 kDa) was achieved by the interaction of anti-Id TB71 with the T cell receptor complex (CD3/Ti). The accessory cell requirement in this response could not be replaced by anti-Id TB71 coupled to Sepharose beads and was not inhibited by Fc receptor blockade. When taken together with the finding that anti-Id TB71-induced proliferation of a T cell clone was restricted by determinants encoded by the major histocompatibility complex, these findings suggested that anti-Id TB71 was presented to 38-kDa antigen-reactive T cells by the same mechanisms as conventional antigenic determinants. That is, both stimulated T cells through the CD3/Ti complex and had to be presented in the context of class II molecules on accessory cells. The finding that the disruption of the integrity of the anti-Id TB71 combining site did not affect T cell responsiveness although antibody binding was ablated implied that anti-Id TB71 may be partially degraded and re-expressed with MHC class II determinants.

The basis for major histocompatibility complex (MHC) and immunoglobulin gene control of helper T cell idiotopes

BALB/c helper T cells, prepared against 2,4,6-trinitrophenyl (TNP)-derivatized syngeneic spleen cells, fail to recognize other hapten modifications [(4-hydroxy-3-nitrophenyl)acetyl, fluorescein isothiocyanate] of syngeneic cells, as well as TNP-derivatized cells from major histocompatibility complex-congenic donors. T helper cell interactions with "presenting" cells and "target" B lymphocytes are inhibited by monoclonal antibodies directed either to the hapten or to I-A molecules on target cells. Helper activity is also inhibited by monoclonal anti-idiotypic antibodies directed to an idiotope expressed by the TNP-binding myeloma protein MOPC460, but not by soluble TNP-protein conjugates. The study of congenic mouse strains revealed that while the fine specificity of TNP recognition and the quantitative levels of M 460 idiotope expression are I-A linked, the expression of the M 460 idiotope by helper cells is controlled by IgCh-linked genes. Absence of anti-idiotope inhibition of helper cells prepared in anti-mu-suppressed mice suggests, however, that immunoglobulin idiotype expression by T cells results from network interactions selecting available lymphocyte repertoires which operate before antigenic stimulation.

Studies of monoclonal antibodies specific for major histocompatibility complex products of the rat. IV. Production and characterization of polyclonal and monoclonal anti-anti-idiotypic antibodies

Polyclonal syngeneic, allogeneic, and xenogeneic and monoclonal syngeneic anti-anti-idiotypic antibodies have been produced against previously described monoclonal anti-idiotypic antibodies with specificity for monoclonal RT1 alloantigen-specific antibodies. The anti-anti-idiotypes could again be shown to be highly specific for the monoclonal anti-idiotype used for the induction of the anti-anti-idiotypic antibodies and to carry the same, or a very similar, idiotype as the original monoclonal idiotypic antibody used to induce the monoclonal anti-idiotypic. Among the 30 syngeneic and allogeneic and the five xenogeneic polyclonal anti-anti-idiotypic antisera and the three monoclonal anti-anti-idiotypes, only one polyclonal antiserum showed binding capacity to the corresponding RT1-encoded antigenic determinants on spleen cells. All the other antibodies were idiotypic but not antigen binding.

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.

Establishment of idiotypic helper T-cell repertoires early in life

Immunoglobulin variable-region (V) genes, it is now recognized, do not encode specific receptors for T lymphocytes. Classical observations on T-cell expression of immunoglobulin idiotypes had remained unexplained until recent experiments showed that immunoglobulin idiotypes expressed by T lymphocytes in normal mice are absent in cells of the same specificity isolated from donors whose B-cell system has been suppressed by administration of anti-mu antibodies from birth. This observation provided evidence for the 'learning' of T-cell idiotypes from the B-cell/antibody system and, therefore, for the importance of idiotypic network interactions in the selection of available lymphocyte repertoires before antigenic challenge. Previously described influences of B cells and/or antibodies on the T-helper (Th) cell compartment would appear to operate at the level of clonal repertoires by complementarities with defined immunoglobulin idiotypes. Other authors, however, had previously shown the striking stability of T-cell idiotype expression in chimaeric animals reconstituted with T and B cells originating from donors showing differential idiotype expression. We have now investigated this apparent discrepancy and present here results demonstrating that immunoglobulin-dependent selection of T-cell (idiotypic) repertoires only operates for the first 3 weeks of life.

The gene encoding the T-cell receptor alpha-chain maps close to the Np-2 locus on mouse chromosome 14

Serological and molecular genetic analyses of T-cell clones have shown that the T-cell antigen receptor apparently comprises two glycosylated, disulphide-linked polypeptide chains (alpha and beta), both of which span the cell membrane. Cloning of the genes encoding the two chains from mouse and human DNA has shown that the alpha- and beta-chains are composed of variable (V) and conserved (C) regions in agreement with peptide mapping data. Gene segments encoding variable and conserved domains of the beta-chain have been identified and undergo rearrangements during T-cell differentiation. The genes encoding the alpha-chain, so far described at the level of complementary DNA clones, also identify DNA rearrangements. Thus, the genes encoding the T-cell receptor show the same structure and dynamic behaviour as immunoglobulin genes, indicating that the two gene families belong to the same supergene family; this evolutionary relationship is supported by the fact that the genes encoding the beta-chain of the T-cell receptor are closely linked to immunoglobulin kappa light-chain genes on chromosome 6 in mouse. In man, however, the beta genes map to chromosome 7 (ref. 14) whereas the kappa-chain genes are located on chromosome 2, indicating that linkage between the two gene families is not needed for proper expression. Here we describe genomic clones encoding the constant portion of the T-cell receptor alpha-chain and map the gene to chromosome 14 in mouse, close to the gene for purine nucleoside phosphorylase (Np-2) which, in man, has been associated with T-cell immunodeficiencies.

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.

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.

Novel immunoglobulin heavy chains are produced from DJH gene segment rearrangements in lymphoid cells

It has been found that most immunoglobulin heavy(H)-chain gene diversity (D) segments carry their own 5' transcriptional promoter element. Transcription of rearrangements which use heavy-chain D and joining (J) segments in B-lymphoid cells ultimately leads to the production of a Dmu messenger RNA which contains the DJH segments linked to the mu heavy-chain constant region. If the D is joined to the JH segment in the appropriate translational reading frame, this Dmu mRNA is translated to yield a short Dmu protein with a variable DJH N-terminus.

A murine T cell receptor gene complex: isolation, structure and rearrangement

We describe here our efforts to develop a systematic strategy for the enumeration and isolation of genes encoding T cell-specific, membrane-associated polypeptides. Of particular importance among the cDNA clones that we have isolated is one which encodes the beta chain of the murine T cell receptor for antigen. The gene product is strikingly similar to immunoglobulin in its variable (V), constant (C), joining (J), and diversity (D) - like elements and the ability of the latter three types of element to assort independently during differentiation. The genomic organization of the constant region locus which encodes this molecule consists of two tandemly arrayed units of the form JC/JC, where the J clusters consist of fourteen distinct elements, many of which may be functional. The two constant regions differ by only four amino acids and both are apparently expressed in T cells of the same phenotype, so they probably do not represent isotypes in the classical sense. The sequences flanking the V, D and J elements are also similar to the conserved heptamer and nonomer sequences of immunoglobulins thought to be important in the recombination of the specific gene segments. These similarities indicate both the common evolutionary origins of these loci and the strong selective pressure that must be operative. The T cell receptor locus differs somewhat from immunoglobulins in the large number of possible J region elements and to some extent in the hypervariable-framework regions of the V region. We and others have mapped this gene to chromosome 6 of the mouse, in the same portion of the chromosome but not closely linked the kappa locus. The significance of the predicted protein structure of the beta chain and its support of the one-receptor model of MHC-antigen recognition are discussed.

Partial characterization of T cell components related to defined VH (VT) markers

Certain antigen-binding surface molecules and factors of T cells possess serological determinants related to immunoglobulin (Ig)-heavy-chain-variable regions (VH). We obtained sufficient quantities (greater than 100 micrograms) of homogenous VH-related T-cell molecules (VTM) for biochemical studies from normal murine thymocytes and by growing large quantities of monoclonal T-cell leukemia lines expressing the determinants. A solid phase immune adsorbent prepared from the IgG fraction of rabbit anti-IgT serum was used to isolate VTM from formic acid-solubilized T cells. The VTM from murine thymocytes and T-cell lines had Mr of 65,000-68,000. The VTM from distinct cell lines differ by isoelectric focusing and resolution of tryptic peptides indicating clonal restriction. VTM lack conventional light- or heavy-chain-constant region determinants but cross-react with antisera directed against defined VHa allotypes and JH peptides. The detection of a cross-reaction with a synthetic JH peptide is consistent with recently published data identifying JH-related sequences in putative T-cell receptor genes. The amino acid compositions of the VTM were distinct from those of mammalian Ig, major histocompatibility complex (MHC) antigens, and viral glycoproteins, but significant similarities occur with Ig V regions or heavy chains of primitive vertebrates. The results indicate that the VH-bearing T-cell products are not classical Ig, but bear limited VH-cross-reactive determinants.

Murine T cell receptor beta chain is encoded on chromosome 6

Southern blot analysis of somatic cell hybrid lines indicates that the beta chain of the T cell receptor for antigen maps to chromosome 6 of the mouse. An experiment testing hybridization of the constant region of this gene to DNA from a hybrid cell line containing a translocation of chromosome 6 supports the localization of this gene to the proximal (centromeric) one-third of chromosome 6, in the same general region as the immunoglobulin kappa chain locus. This may be another indication of the shared evolutionary origins of the genes encoding both T and B cell antigen recognition.

Internal complementarities in the immune system: regulation of the expression of helper T-cell idiotypes

More than half of BALB/c helper T lymphocytes specific for 2,4,6-trinitrophenyl (TNP)-modified syngeneic spleen cells are inhibited in their proliferative responses to antigen-presenting cells and in their cooperation with B lymphocytes by monoclonal anti-idiotypic antibodies directed to a TNP-binding BALB/c myeloma protein (MOPC 460). This inhibition is specific for anti-TNP-self helper cells of BALB/c origin and is controlled by IgCh-linked genes, as it is not observed with CB.20 helper cells of the same specificity. In contrast, anti-TNP-self helper cells prepared from BALB/c mice that were chronically suppressed with anti-mu chain antibodies and possessed no B lymphocytes were not inhibited by anti-idiotypic antibodies. We conclude that the B-cell antibody repertoires contribute to the selection of the (idiotypic) T-helper-cell repertoires.

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.

Induction of immunity to a human tumor marker by in vivo administration of anti-idiotypic antibodies in mice

Anti-idiotypic antibodies are described that were raised against murine monoclonal antibody 8.2, an antibody specific for a human melanoma-associated cell surface marker called p97. The 8.2 idiotopes recognized by this anti-idiotypic antiserum are binding site-associated and are shared by other monoclonal anti-p97 antibodies with the same specificity as antibody 8.2. Mice immunized with the anti-idiotype demonstrate delayed-type hypersensitivity reactions when challenged with melanoma (p97-positive) tumor cells.

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.

Presence of IgT-C and I-A subregion-encoded determinants on distinct chains of monoclonal antigen-specific augmenting factor derived from a T cell hybridoma

Monoclonal antibodies specific for mouse T cell alloantigens, Tindd and Tsud, linked to the Igh-1 locus on chromosome 12, were used to directly define the antigen-binding molecule produced by a cloned hybridoma. The T cell hybridoma, FL10, was established from antigen-binding T cells of A/J mice. FL10 produces an antigen-specific augmenting T cell factor (TaF) that bears a unique I region-controlled determinant (I-A) and has antigen-binding capacity. The Tindd, but not the Tsud, determinant was detected on the surface of FL10. The presence of both Tindd and I-A subregion-controlled determinants on FL10-derived TaF was directly demonstrated by the adsorption of TaF with immunoadsorbents prepared with monoclonal antibodies. The Igh-1-linked T cell alloantigen, Tsud, was not found on TaF. Further experiments indicated that Tindd is present on the antigen-binding polypeptide chain and not on the second chain bearing the I-A determinant. Despite the presence of the Tindd determinant on hybridoma-derived TaF, augmentation induced by TaF was restricted by the H-2 type of the responding mice and not by the Igh-1 allotype.

Elicitation and detection of in vitro H-2-linked Ir gene regulated antibody responses to poly(LTyr, Glu)-poly(DLAla)--poly(LLys)

A microculture system is described in which secreted antibody responses to the synthetic polypeptide (T,G)-A--L were obtained in vitro. Responses were highly reproducible, antigen-dependent, antigen-specific, and under H-2-linked Ir gene control. Critical elements in the system include the schedule of in vivo antigen-priming, removal of the stimulating antigen after 3 days of culture, and a sensitive detection system (double-antibody ELISA). This system should be useful in the analysis of the mechanism of action of Ir genes as well as the mechanisms by which anti-idiotype antibodies modulate immune responses.

Anti-idiotypic antibodies to anti-HLA receptors induced by pregnancy

We have previously shown that lymphoblasts alloactivated in vitro acquire the capacity of stimulating the autologous mixed lymphocyte response. This response is anti-idiotypic in nature because lymphocytes so primed display accelerated memory responses only when restimulated by autologous lymphoblasts that have been alloactivated against the same HLA-DR antigen. Based on this observation we have postulated that the absence of HLA antibodies in alloimmunized human subjects may be due to the development of autoantibodies that react with the anti-HLA receptors expressed by primed lymphocytes or by anti-HLA antibodies or both. This hypothesis has been confirmed in the present investigations which show that sera from parous women react with autologous T lymphoblasts primed in 5-day mixed lymphocyte culture against their husband-i.e., with lymphoblasts expressing receptors for the immunizing donor. Anti-HLA receptors expressed by T and B lymphocytes seem to share serologic determinants because sera that bind to autologous alloactivated lymphoblasts are also capable of inhibiting the anti-HLA activity of autologous and homologous sera. Auto-anti-idiotypic antibodies inhibit the autologous mixed lymphocyte response to autologous alloactivated lymphoblasts, a phenomenon whose in vivo correlate may reside in autoinhibition of anti-HLA antibody formation and of allograft immunity. Because auto-anti-idiotypic antibodies were found in sera from all parous women tested, the hypothesis that nonresponsiveness to alloantigens exists as a state per se is not likely. The passive transfer of antireceptor (idiotype) immunity by use of antibodies from pregnant women's sera may provide a powerful tool for specific suppression of allograft rejection.

Defective induction of antigen-reactive proliferating T cells in B cell-deprived mice. II. Anti-mu treatment affects the initiation and recruitment of T cells

Mice injected from day of birth onwards with rabbit anti-mouse IgM (antim-mu) antibodies were found to be B cell-deficient and defective for the induction of antigen-reactive proliferating T cells (TPRLF). This defective induction was not due to the absence of circulating antigen-specific antibodies since the daily injections of such antibodies during exposure to antigen did not restore the ability of anti-IgM treated animals to generate TPRLF. Analyzing the cellular events implicated in the induction of virgin antigen-reactive T cells, anti-mu-treated mice manifested impairment of the three interacting cell types involved in the induction of TPRLF. Thus, peritoneal and splenic antigen-presenting cells from such animals were impaired in their capacity to signal a primary antigen-specific T cell reaction. Their splenic lymphocytes could not function as initiator cells in transferring immunogenic signals to recruit TPRLF in normal recipients. Potent antigen-specific splenic initiator cells failed to induce the recruitment of specific TPRLF in anti-mu-treated mice. The defective induction of TPRLF in anti-mu-treated mice may be due to a functional impairment of cells expressing membrane-bound IgM molecules which seemingly play a central role in the transfer of immunogenic signals for the recruitment of antigen-specific circulating T cells. We suggest that splenic B cells function as initiators in the transfer of antigen-induced signals from peritoneal antigen-presenting cells to T cells. These seems to be the primary targets of anti-mu treatment.

Identification of an idiotypic marker of a major regulatory T cell of the immune response in B10.BR mice to ferredoxin. The relationship of idiotypic regulation to conventional hapten-carrier effects

An anti-idiotypic antiserum was raised in rabbits to a monoclonal antibody (Fd-1) with specificity for one (the N epitope) of the two antigenic epitopes found on the ferredoxin (Fd) molecule. The anti-idiotypic antiserum (anti-Fd-1) was used to demonstrate that the Fd-1 idiotype was expressed at significant levels in most anti-Fd antisera raised in B10.BR mice. Examination of antisera raised in other mouse strains demonstrated that expression of this idiotype mapped to the IgH gene complex and was found in the antisera of all mouse strains examined with the Ig-1 allotype. When splenocytes from Fd-immune B10.Br mice were treated with anti-Fd-1 and transferred to irradiated syngeneic recipients, the adoptive secondary response was significantly higher in animals receiving treated cells as opposed to control animals, which received normal rabbit serum-treated cells. This response produced a net increase in antibody to both determinants, and the relative amount of Fd-1 idiotype was not significantly altered. Further studies with separated cell populations showed that the overall increase of anti-Fd antibody produced was attributable to the effects of the anti-idiotypic serum on a population(s) of T cells. Treatment of mice with the Fd-1 monoclonal antibody (which should react with anti-idiotypic cells) had an analogous effect to that of the anti-idiotype, in that mice so treated produced higher concentrations of anti-Fd antibodies when they were immunized and these antibodies exhibited net increases to both determinants. A model is presented to explain these results.

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.

Negative feedback regulation of contact sensitivity to DNFB by autoanti-idiotypic antibody

Contact sensitivity to 2,4-dinitrofluorobenzene is maximal six days after sensitization but declines rapidly, due to autoanti-idiotypic antibodies produced by the host. The studies presented here indicate that this down regulation by anti-Id is a C-independent active process involving a subset of Ia+ T cells in the immune lymph node cell population. Depleting immune LN cells of Ia+ T cells renders them insensitive to inhibition by anti-Id alone, although the same population is inhibited by treatment anti-Id plus C. This cell population is rendered sensitive to inhibition by anit-Id alone by adding untreated DNFB-sensitized LN cells but not by adding normal LN cells. Further studies showed that suppression by anti-Id-activated Ia+ T cells occurs locally at the skin test site and is antigen nonspecific. These data indicate that the natural regulation of CS to DNFB by autoanti-Id antibodies involves a negative feedback regulatory loop.

Antigen receptors on murine T lymphocytes in contact sensitivity. III. Mechanism of negative feedback regulation by auto-anti-idiotypic antibody

Contact sensitivity (CS) to 2,4-dinitrofluorobenzene (DNFB) is maximal 6 d after sensitization but declines rapidly. Previous studies have shown that this rapid decline is due to auto-anti-idiotypic (anti-Id) antibodies produced by the host. The present study was done to investigate the mechanism(s) involved in his down-regulation of the effector phase of the CS reaction. Using transfer of CS to mimic the natural effector phase, we found that the inhibition of transfer by treating DNFB-sensitized lymph node (LN) cells with either auto-anti-Id or syngeneic anti-Id serum is complement (C) independent. This inhibition requires Ia+ T cells in the immune population. Depleting immune LN cells of Ia+ T cells rendered them insensitive to inhibition by anti-Id alone, although the same population is inhibited by anti-Id plus C. This cell population is rendered sensitive to inhibited by anti-Id alone by addition of untreated DNFB-sensitized LN cells, but not by addition of normal LN cells. Further studies showed that the suppression of immunity by anti-Id-activated Ia+ T cells is not systemic, but rather occurs locally at the skin test site and is antigen nonspecific. We interpret these data to indicate that the natural regulation of CS to DNFB by auto-anti-Id antibodies is an active process that involves a negative feedback regulatory loop.

The expression and functional involvement of nuclease- specific idiotype on nuclease-primed helper T cells

The expression and functional significance of idiotypic determinants on antigen-specific helper T (Th) cell populations for responses to Staphylococcal nuclease (Nase) were evaluated in an in vitro antibody response system. Trinitrophenyl (TNP)- specific plaque-forming cell responses to TNP-conjugates of Nase (TNP-Nase) were shown to require the cooperation of Nase-primed Th cells as well as unprimed B and accessory cells. The expression on these antigen-primed Th cells of idiotypic determinants cross-reactive with those on anti-Nase antibodies was demonstrated by the specific elimination of Th cells for TNP-Nase by treatment with affinity-purified anti-idiotypic antibodies plus complement. The susceptibility of Nase-primed Th cells to elimination by such treatment was specific in that anti-idiotypic antibodies affected Th cells only from strains normally expressing the same (or a cross-reactive) idiotype on anti-Nase antibodies. A functional role of the idiotypes expressed on Nase-primed Th cells was suggested by the fact that anti-idiotypic antibody present throughout the period of culture, in the absence of complement, suppressed responses to TNP-Nase in an antigen- and strain-specific manner. It was further shown, by cell mixing experiments, that this inhibition appeared to occur at the level of the Th cells and was not dependent on the strain of origin of the B cells. Thus, antigen-specific Nase-primed Th cells express strain-specific idiotypic determinants cross-reactive with, or identical to, those of anti-Nase antibodies. These cell surface idiotypic determinants appear to be functionally involved in the activity of Th cells for the induction of antibody responses to TNP-Nase in vitro.