D-glutamic Acid And D-lysine Research Articles

Production of highly specific anti-testosterone antiserum by an immunotolerance method.

Anti-testosterone antisera were produced by pretreatment of rabbits with 15 alpha-carboxymethyl-5 alpha-dihydrotestosterone linked to a copolymer of D-glutamic acid and D-lysine (D-GL) before immunization with the bovine serum albumin conjugate of 15 alpha- and 15 beta-carboxymethyltestosterone. The specificity for 5 alpha-dihydrotestosterone of the antitestosterone antisera was considerably improved.

Production of rabbit antibody specific for amino-terminal residues of cholecystokinin octapeptide (CCK-8) by selective suppression of cross-reactive antibody response

Antibody specific for the amino-terminal region of cholecystokinin octapeptide (CCK-8) was generated in a highly reproducible way in New Zealand white rabbits by a novel immunization procedure which involves immunization with CCK-8 peptide conjugate coupled with keyhole limpet hemocyanin (KLH) and inhibiting cross-reacting antibody formation by treatment of the animals with a potent tolerogenic conjugate of β-alanyl-tetragastrin and a copolymer of D-glutamic acid and D-lysine ( D-GL). The antisera thus produced specifically react with an amino-terminal region of CCK-8 but not with the non-sulfate form of CCK-8, nor with the carboxy-terminal region which shares a cross-reactive determinant among gastrin and cholecystokinin-related peptides (caerulein, CCK-4, CCK-8, CCK-33 and CCK-39). The antisera produced by this method allowed us to measure specifically CCK in extracts from tissue such as duodenum containing gastrin and CCK at comparable levels.

Augmentation of auto-anti-idiotypic antibody production by hapten-reactive helper T lymphocytes

Augmented auto-anti-idiotypic antibody production was effectively achieved by immunization of mice with haptenated myeloma protein in the presence of hapten-reactive helper T lymphocytes. Hapten-reactive helper T-lymphocyte activities were raised in BALB/c mice by immunization with para-azobenzoate (PAB)-derived mouse gamma globulin (MGG) prepared by amidination reaction (PAB im-MGG). Helper T cell activity was effectively enhanced by pretreatment of mice with a PAB-derived nonimmunogenic copolymer of D-glutamic acid and D-lysine ( D-GL) (PAB- D-GL) 3 days before priming with PAB im-MGG; PAB- D-GL is a potent tolerogen of both PAB-specific suppressor T lymphocytes and PAB-specific B cells. After induction of these enhanced PAB-reactive helper T lymphocytes, mice were immunized with PAB-coupled TEPC-15 myeloma protein (PAB im-T-15), which was also prepared by amidination reaction. Mice immunized in this way manifested strikingly enhanced titers of auto-anti-idiotypic antibodies, specific for the T-15 idiotype, as compared to control mice which had not been preimmunized with PAB im-MGG. The ability of PAB im-MGG preimmunization to facilitate auto-anti-idiotypic antibody production was due to the activity of PAB-reactive helper T cells since PAB-specific B cells had been abolished by prior treatment with PAB- D-GL. The implications of this model for future studies on immunological engineering the analysis of idiotype network phenomena are discussed.

Immunologic Tolerance to Allergenic Protein Determinants: Properties of Tolerance Induced in Mice Treated with Conjugates of Protein and a Synthetic Copolymer of D-Glutamic Acid and D-Lysine (D-GL)

Conjugates of proteins and the synthetic copolymer of D-glutamic acid and D-lysine (protein-D-GL) reproducibly induce significant unresponsiveness to the protein antigens in experimental mice. Proteins studied include ovalbumin and antigen E of ragweed extract, the major allergen of ragweed pollen. The unresponsive state 1) can be induced in both unsensitized and previously sensitized experimental animals, 2) is selectively confined to responses of the IgE antibody class, 3) is long lasting, and 4) is highly antigen specific. IgE antibody responses can also be suppressed by administering comparable doses of unconjugated protein alone; however, the unresponsive state induced in this manner is only transient and rebound production of IgE antibody is often observed. Results from the studies of the cellular basis of the protein-D-GL induced unresponsiveness demonstrate that 1) protein-D-GL conjugates do not induce unresponsiveness at the level of protein-specific B cells, 2) tolerance is not induced by virtue of a detectable antigen-specific suppressor T cell mechanism, 3) tolerance is most probably induced in the antigen-specific helper T cell populations. The significant IgE-selective and antigen-specific tolerogenic activity of protein-D-GL conjugates make these compounds potential candidates for use as therapeutic agents in the treatment of IgE-mediated human allergic disorders induced by protein allergens.

Immunological tolerance to allergenic protein determinants: a therapeutic approach for selective inhibition of IgE antibody production.

Administration of stable conjugates prepared by coupling protein antigens such as ovalbumin or antigen E of ragweed extract to the synthetic random copolymer of D-glutamic acid and D-lysine (D-GL) is effective in inducing a state of long-lasting, antigen-specific immunological tolerance in experimental animals. A striking aspect of the tolerance induced by protein-D-GL conjugates is the remarkable selectivity of the tolerance for antibody responses of the IgE class. Protein-D-GL conjugates of either type were capable of inducing such tolerance both in unsensitized and in previously sensitized animals when administered in appropriate doses. Comparable doses of unconjugated proteins were likewise capable of suppressing IgE antibody production, although the duration of suppression in these cases was significantly less than that observed with protein-D-GL conjugates. If such conjugates act in man as they do in experimental animals, they could be of great value as therapeutic agents in selectively diminishing IgE antibody production while sparing antibody production in the IgG class.

Immunological properties of conjugates of ragweed pollen antigen E with methoxypolyethylene glycol or a copolymer of D-glutamic acid and D-lysine.

The major allergen of ragweed pollen, antigen E, was modified by coupling its amino acid groups with either methanol, methoxypolyethylene glycol (MPEG) of 5,000 daltons, or a synthetic copolymer of D-glutamic acid and D-lysine (DGL) of 34,000 daltons, all appropriately activated. The conjugates were characterized chemically and immunologically. Compared to the native antigen, the methoxy conjugate showed little reduction in allergenic activity, but the other two conjugates showed strong reductions, as measured by heterologous passive cutaneous anaphylaxis in rats sensitized with murine anti-antigen E reaginic sera. The MPEG conjugate was apparently nonimmunogenic in mice known to be high responders to the native antigen. MPEG and DGL conjugates retained the immunosuppressive property of the native antigen as subcutaneous treatment of antigen E sensitized mice with these two conjugates led to significant long-lasting depression of their antigen E-specific IgE and IgG antibody levels. These immunological changes are believed to result from reduction of antigenic valency and specificity upon coupling the bulky molecules to the protein antigens.

Regulatory functions of hapten-reactive helper and suppressor T lymphocytes. III. Amplification of a generation of tumor-specific killer T-lymphocyte activities by suppressor T-cell-depleted hapten-reactive T lymphocytes.

2,4.6-trinitrophenyl (TNP)-reactive T-cell activities were raised in mice by immunization with TNP-isologous mouse gamma globulin. After establishing that TNP-reactive T lymphocytes can serve as amplifier cells for induction of killer T lymphocytes in allogeneic system, we explored the possibility of this hapten-reactive T-cell system to amplify tumor-specific killer T-lymphocyte activity in the syngeneic system. We utlized relatively weak immunogenic syngeneic plasmacytoma X5563 in C3H/He mice. Analysis of the TNP-reactive T-cell activities revealed that such T lymphocytes express the biological functions of both major subtypes of regulatory T cells, namely suppressors and helpers, and that TNP-reactive suppressor and helper T lymphocytes, respectively, differ in their relative susceptibility to specific inactivation by TNP conjugates of the nonimmunogenic D-amino acid copolymer, D-glutamic acid, and D-lysine (D-GL). By taking advantage of the relative susceptibility-difference to TNP-D-GL, selective inactivation of TNP-reactive suppressor T cells was induced by appropriate treatment with TNP-D-GL, and the generation of TNP-reactive helper T-cell activity was amplified. The supplement of augmented TNP-reactive helper T-cell activity to the system at the immunization with syngeneic X5563 with TNP-haptenation, resulted in a striking augmentation of induction of tumor-specific killer T-lymphocyte activity, and a considerable number of hosts survived after the challenge with lethal dose of viable tumor cells. Thus, appropriate manipulations designed to induce potent hapten-reactive helper T-lymphocytes provided the potential for a very effective mode of immunoprophylaxis against tumor.

Induction of T Lymphocyte Responses to a Small Molecular Weight Antigen

Abstract 2,4-Dinitrophenyl (DNP) coupled to the copolymer D-glutamic acid and D-lysine (D-GL) induces B cell tolerance but not T cell tolerance. This implies either a lack of DNP determinant recognition by T cells or a substantial difference in tolerance mechanisms for the two cell types. In the present study D-GL was conjugated with the well-defined determinant azobenzenearsonate (ABA) coupled to single amino acids shown here and previously by others to trigger effectively T lymphocytes. The experiments presented here demonstrate that these ABA conjugates of D-GL, although capable of diminishing anti-ABA antibody production, completely fail to render ABA-specific T lymphocytes tolerant thus drawing us to conclude that there are significant operational differences in the mechanisms of tolerance induction in T and B lymphocytes, respectively.

The mechanism of tolerance induction in thymus-derived lymphocytes; I. intracellular inactivation of hapten-reactive helper T lymphocytes by hapten-nonimmunogenic copolymer of D-amino acids.

Treatment of a p-azobenzoate (PAB) derivative of a copolymer of D-glutamic acid and D-lysine (D-GL) induced a profound state of unresponsiveness to PAB-reactive helper T lymphocytes generated in PAB-mouse gamma globulin (MGG)-primed mice. This unresponsiveness in T lymphocytes was specific for PAB-reactive cells, since the bacterial alpha-amylase-, keyhole limpet hemocyanin-, or ovalbumin-primed helper T lymphocytes were not suppressed by PAB-D-GL treatment. Taking advantage of the relative ease with which PAB-D-GL can induce specific unresponsiveness to helper T lymphocytes in an animal previously primed with PAB-MGG, it was possible to approach certain questions concerning the mechanisms of tolerance-induction and the fate of tolerant helper T lymphocytes in the PAB-D-GL model by utilizing a classical adoptive cell transfer systemmelimination of the possibility of carry-over of the tolerogen with cells or of the generation of suppressor cells as the result of PAB-D-GL treatment as an explanation of the suppression of helper T-cell activity strongly inplicates the existence of a central intracellular mechanism of specific tolerance on the helper T-cell level. The possibility that suppression of the activity of PAB-reactive helper T lymphocytes by PAB-D-GL reflects simple blocking of surface receptor molecules on T lymphocytes was ruled out as it was found that the helper activity of PAB-reactive cells was minimally suppressed even when PAB-D-GL was directly exposed in vitro to helper T lymphocytesmmoreover, the most conclusive evidence on te the tolerant state induced by in vivo exposure of primed T cells to PAB-D-GL. It appears, therefore, that specific tolerance induced by PAB-D-GL' TO PAB-reactive helper T lymphocytes is an example of irreversible inhibition of T-cell reactivity to antigen, reflecting yet to be determined events at the intra- and subcellular levels.

Induction of Tolerance to Nucleic Acid Determinants by Administration of a Complex of Nucleoside d-Glutamic Acid and d-Lysine (D-GL)

The administration of nucleosides coupled covalently to the copolymer of D-glutamic acid and D-lysine (D-GL) or to its stereoisomer, L-GL, induces a state of nucleoside (NUC)-specific tolerance in inbred SJL and BALB/c mice, irrespective of their immune status at the time of treatment. Such tolerance is characterized by the inability of treated animals to mount either primary or secondary, intact or adoptive, anti-NUC antibody responses following immunization with a highly immunogenic conjugate of NUC-Keyhole limpet hemocyanin. These observations have potential therapeutic importance in autoimmune processes involving anti-DNA antibody production.

Immunological tolerance in bone marrow-derived lymphocytes. II. Effects of allogeneic cell interactions and enzymatic digestion with trypsin or inactivated hapten-specific precursors of antibody-forming cells.

The studies presented here have focused on the important question of reversibility of inactivation of DNP-specific B lymphocytes induced by the DNP derivative of the copolymer of D-glutamic acid and D-lysine (D-GL). In so doing, we have analyzed the capacity of a strong T-cell stimulus, such as that provided by the allogeneic effect, and of gentle enzymatic treatment with trypsin to alter, prevent, or reverse the tolerance induced by DNP-D-GL. Under experimental conditions in which DNP-specific B lymphocytes were exposed first to the tolerogenic molecule, and rendered markedly unresponsive by such exposure either in vitro or in vivo, subsequent exposure to an allogeneic effect failed to appreciably reverse or alter the tolerant state. This contrasts directly with the capacity of DNP-D-GL to serve as a stimulus for DNP-specific B lymphocytes when the critical moment of specific binding occurs subsequent to the development of an allogeneic effect. In another series of experiments, the effects of enzymatic treatment with trypsin on the tolerant B-cell population were found to vary depending on the stage of tolerance at which such treatment was performed. Thus, when exposure of cells to DNP-D-GL for a relatively short time in vitro is carried out at low temperature (4 degrees C), the development of tolerance can be interceded by immediate trypsinization. In contrast, cells exposed to DNP-D-GL for longer periods of time and/or at 37 degrees C were not reversed to responsiveness by trypsinization. These data were interpreted to indicate that: (a) the effect(s) of trypsin in reversing (or preventing) tolerance at the cellular level does not depend necessarily on the susceptibility of the tolerogenic moiety to the action of the enzyme, and (b) the generation of the tolerance-inducing signal involves metabolic cellular processes that can be delayed somewhat by low temperature leaving such cells relatively more susceptible to intercedent manipulations such as trypsinization. Taken collectively, therefore, the evidence obtained in these studies reinforces the concept of central tolerance in B cells induced by DNP-D-GL as reflecting sub- or intracellular inactivating events.

Induction of immunological tolerance in bone marrow-derived lymphocytes of the IgE antibody class.

Administration of the 2,4-dinitrophenyl (Dnp) determinant conjugated to the "nonimmunogenic" copolymer of D-glutamic acid and D-lysine (D-GL) induces Dnp-specific immunological tolerance which is essentially restricted to bone marrow-derived (B) lymphocytes. Previous studies have demonstrated tolerance induction by Dnp-D-GL in predominantly B lymphocytes of the IgG class. The present studies establish and analyze conditions for tolerance induction in Dnp-specific B lymphocytes of the IgE antibody class by taking advantage of: (i) the relatively easy capacity to induce tolerance with Dnp-D-GL in an animal or cell population previously primed to the Dnp determinant; (ii) previously established parameters for the successful adoptive transfer of Dnp-specific IgE antibody responses; and (iii) the capacity to induce, and maintain a state of Dnp-specific tolerance with Dnp-D-GL in adoptive transfer responses. Using these approaches, we have successfully rendered Dnp-specific B cells of the IgE class profoundly and apparently irreversibly tolerant after exposure of such cells to Dnp-D-GL. These observations represent a starting point of wide potential for solving many therapeutic problems concerned with clinical allergies.

Carrier Function in Anti-Hapten Antibody Responses

Abstract Guinea pigs primed with 2,4-dinitrophenyl (DNP)-ovalbumin (OVA) will develop markedly enhanced secondary anti-DNP antibody responses to the heterologous conjugate DNP-bovine γ globulin (BGG) provided that they have been supplementally immunized with appropriate amounts of BGG. This phenomenon reflects the enhancing influence of BGG-specific thymus-derived (T) lymphocytes on anti-DNP antibody production. The present studies demonstrate that such enhancing T cell influences can be abolished by the following manipulations: 1) simultaneous supplemental immunization with two unrelated proteins such as BGG and keyhole limpet hemocyanin (KLH) or glucose oxidase (GO) significantly diminished the secondary anti-DNP response upon challenge with a DNP-conjugate of one of the carriers employed; 2) the intraperitoneal injection of soluble BGG, in the appropriate dose range, 1 day before secondary DNP-BGG challenge completely abolishes the anti-DNP response regardless of whether BGG alone or BGG together with KLH had been used in the supplemental immunization; 3) a challenge with soluble KLH 1 day before secondary challenge with DNP-BGG inhibits the anti-DNP response provided KLH had been administered simultaneously with BGG in the supplemental immunization. The failure to observe similar suppression when KLH was replaced by a copolymer of d-glutamic acid and d-lysine (D-GL) which is nonimmunogenic for T cells indicates that this suppression is a reflection of a T cell-mediated influence. We have interpreted these observations to indicate the production of soluble inhibitory mediators in phenomena such as antigen-induced suppression (“antigenic competition”) and, furthermore, that the elaboration of such mediators is most likely by T lymphocytes. Reasons for favoring the concept that enhancing or inhibitory influences on antibody production represent two ends of the spectrum of regulation exerted, perhaps, by the same T cell product are discussed.

Immunological tolerance in bone marrow-derived lymphocytes. I. Evidence for an intracellular mechanism of inactivation of hapten-specific precursors of antibody-forming cells.

Administration of the 2,4-dinitrophenyl (DNP) derivative of the copolymer of D-glutamic acid and D-lysine (D-GL) to inbred mice induces a state of DNP-specific tolerance in such animals irrespective of their immune status at the time of treatment. Taking advantage of the relative ease with which DNP-D-GL can induce tolerance in an animal previously primed with an immunogenic DNP-carrier conjugate, we have established conditions for tolerance induction in an adoptive cell transfer system. Thus, the adoptive secondary anti-DNP antibody response of DNP-keyhole limpet hemocyanin (KLH)-primed spleen cells was completely, or almost completely, abolished by exposure of such cells to DMP-D-GL either in vivo or in vitro. Tolerance induction in vivo occurred irrespective of whether the DNP-primed cells were exposed to DNP-D-GL in the donor animal before adoptive transfer or in recipient mice after transfer. In the latter situation, it was possible to show that tolerance induction in this model occurs very rapidly (1 hr) and with relatively low doses of tolerogen (50 microg). Incubation of DNP-KLH-primed cells with DNP-D-GL in vitro under varying culture conditions also resulted in depression of the adoptive secondary response of such cells, although the kinetics and degree of tolerance induction in this way were slightly different from that obtained by in vivo tolerization. Utilizing the adoptive transfer tolerance system, it was possible to approach certain questions concerning the mechanism of tolerance induction and fate of tolerant bone marrow-derived (B) lymphocytes in the DNP-D-GL model. The possibility that suppression of anti-DNP antibody from the DNP-D-GL reflects blocking of surface receptor molecules on B lymphocytes has been ruled out by several experimental observations. The most conclusive evidence on this point derives from the failure of enzymatic treatment with trypsin to reverse the tolerant state induced by in vitro exposure of primed cells to DNP-D-GL, whereas trypsinization completely restored the immunocompetence of DNP-KLH-primed cells rendered unresponsive by exposure to DNP-ovalbumin in vitro. The present studies also demonstrate that the tolerant state induced by DNP-D-GL represents a predominantly irreversible inactivation of specific B lymphocytes. This conclusion is derived from experiments in which it was found that tolerance was maintained through as many as two serial adoptive transfers performed over a period of time of at least 24 days from the single exposure of such cells to the tolerogen. Moreover, the possibility that maintenance of tolerance through such serial transfers was due to inadvertent transfer of tolerogenic doses of DNP-D-GL was definitively ruled out. It appears, therefore, that DNP-specific tolerance induced by DNP-D-GL is an example of irreversible inhibition of cell reactivity to antigen reflecting yet-to-be-determined events at the intra- and subcellular levels.

Hapten-specific tolerance. Preferential depression of the high affinity antibody response.

The induction of tolerance in guinea pigs with a 2,4-dinitrophenyl (DNP) derivative of a copolymer of copolymer of D-glutamic acid and D-lysine (D-GL) leads to a preferential depression of the capacity to produce high affinity anti-DNP antibody in response to immunization with DNP-guinea pig albumin. Thus, immunization 2 wk after tolerance induction with 3 mg of DNP-D-GL results in an immune response in which individual plaque-forming cells (PFC) secreting high affinity anti-DNP antibody are absent and in which the affinity of circulating anti-DNP antibody is reduced. A similar, but less marked, suppression is seen when 0.3 mg of DNP-D-GL is used for tolerance induction. If immunization is delayed until 2 months after tolerance induction, then suppression is restricted to the highest avidity PFC group. Our data is consistent with a state of tolerance in the pool of precursors of anti-DNP antibody-secreting cells induced as a result of their interaction with DNP-D-GL in the absence of specific "helper" cells, which appear to be lacking for DNP-D-GL. In such a situation, the affinity of receptors on precursor cells for tolerogen and the concentration of tolerogen appear to be crucial determinants of whether an individual cell will become tolerant.