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Biomedical subjects

Z Eshhar

Publications and source records attributed to Z Eshhar.

124 records · Page 7Linked to original sources
PubMed1976

Induction if immunological tolerance to the major antigenic determinant of penicillin: a therapeutic approach to penicillin allergy.

High titered IgE, IgG, and IgM antibody responses to the major antigenic determinant of penicillin, the benzylpenicilloyl hapten, were elicited by the intraperitoneal injection of the hapten coupled to keyhole limpet hemocyanin mixed with the appropriate adjuvant. However, treatment of such mice with the benzylpenicilloyl derivatized synthetic copolymer of D-glutamic acid and D-lysine, either before or after primary immunization, resulted in significant suppression of the subsequent anti-benzylpenicilloyl antibody responses of the IgE and IgG classes, as measured at the humoral and cellular levels. The state of tolerance induced by benzylpenicili-poly(DGlu, Lys) was highly specific, of long duration, and could be induced in a manner that would be appropriate for clinical use. These results provide a direct demonstration of the potential application of the poly(DGlu, Lys) immunotherapeutic approach to penicillin allergy in humans.

Antibody Formation↗
PubMed1975

Thymus-derived rat lymphocyte receptor for cell surface antigens is a nonserologically defined product of the major histocompatibility gene complex.

Recognition of cell surface antigens by nonsensitized thymus-derived rat lymphocytes is not affected by antisera against immunoglobulin, yet can be effectively blocked by treatment of the lymphocytes with alloantisera raised against lymphoid cells. However, allo antisera induced by nonlymphoid cells do not inhibit recognition. Adsorption of blocking antisera on immunoglobulin-Sepharose columns does not decrease their blocking activity. Absorption of blocking alloantisera with liver and kidney homogenates removes the cytotoxic alloantibodies, yet does not affect the capacity of the antisera to block recognition. Anti-H1-1 alloantisera block antigen recognition only of lymphocytes of strains that share the H1-1 locus. These results suggest that the constant part of the thymus-derived lymphocyte receptor for cell-surface antigens is a product of the rat major histocompatibility locus, which is not identical with the serologically defined antigens.

Animals↗
PubMed1975

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.

Animals↗
PubMed1974

Ferritin, a Hodgkin's disease associated antigen.

Antigens which exist in high frequency in tumor tissues of patients with Hodgkin's disease have been obtained in relatively concentrated form by gel chromatography procedures. Further purification and analysis of these antigens performed in the present study have demonstrated that the antigen of fast electrophoretic mobility (F-antigen) is normal tissue ferritin. The identification of F-antigen as ferritin has been made on the basis of comparative physicochemical and immunological analyses of purified F-antigen and normal ferritin. Thus, F-antigen was found to contain iron and to be similar to ferritin in molecular weight, amino-acid composition, electrophoretic mobility, isoelectric distribution, and immunological reactivity. Absorption of a monospecific heterologous anti-F antiserum with normal tissue ferritin completely removed all anti-F antibody activity. Moreover, the absorption of polyspecific heterologous antiserum to crude Hodgkin's extracts, which contains antibodies reacting with F-antigen, the slower migrating S-antigen, and a third specificity present in lysates of normal peripheral blood lymphocytes (PL-antigen), with ferritin, removed only anti-F activity, thus distinguishing the S- and PL-antigens from ferritin. The existence of ferritin in high quantities in serum of Hodgkin's disease patients may provide a tool of potential diagnostic and prognostic importance in the management of this disease.

Amino Acids↗
PubMed1968

Transport of 3-o-Methylglucose Into and Out of Storage Cells of Daucus carota.

The movement of labeled 3-o-methylglucose (MeG) into and out of thin carrot discs has been followed in order to gain information on sugar entry and exit mechanisms. Little or no metabolism of this derivative appears to occur in the tissue, since no products were detected either by chromatography or by analysis of respiratory CO(2).The curve relating entry to external concentration deviated somewhat from a rectangular hyperbola but suggested a carrier mechanism. Glucose and MeG each competitively inhibited the uptake of the other. K(i) for MeG was estimated to be 3 times the K(m) for its uptake.When discs incubated in MeG were transferred to H(2)O, MeG lost to the solution from the Free Space was re-absorbed against a 7-fold concentration gradient.The addition of unlabeled MeG or glucose to the medium surrounding discs which had been maintaining a ratio of internal to external MeG of 75:1 brought about release of stored isotope. This was probably not due to exchange diffusion stricto sensu.Efflux of previously absorbed isotopic MeG into a medium containing unlabeled MeG or glucose was temperature-sensitive. The kinetics of efflux were complex and did not suggest a simple diffusion process related to overall MeG content. However there is evidence (including the falling rate of exit with time) that slow diffusion (or slow release from adsorption) contributed substantially to efflux. The source of this flow appeared to be neither the readily accessible Free Space nor the main storage compartment. Calculation indicated that the volume of this "slow diffusion compartment" might be about 1% of the total volume of the discs.

Journal Article↗
PubMedDate not supplied

Tumor-specific T-bodies: towards clinical application.

Unlike antibodies, T cells are well suited to penetrate and destroy solid tumors. The T-body approach combines antibody recognition and T cells effector function. It is based on T cells expressing chimeric receptors composed of antibody-derived Fv or scFv as their extracellular recognition elements joined to lymphocyte triggering molecules. This receptors can redirect the specificity of T cells in an MHC independent manner. Upon encountering their target cells, T-bodies are able to undergo specific stimulation for interleukin/cytokine production, and kill hapten-modified or tumor cells in model systems both in vitro and in vivo. T cells expressing chimeric receptors made of antitumor antibodies are able to discriminate between a tumor and normal cell with negligible bystander cytotoxicity. Further studies should be carried out to evaluate and optimize the persistence, homing patterns and reactivation potential of T-bodies in the body.

Antibodies, Neoplasm↗
PubMedDate not supplied

Characterization of soman-binding antibodies raised against soman analogs.

The production of antibodies against the highly toxic organophosphorus compound soman (GD) has been undertaken. Monoclonal antibodies were raised against two structural analogs of soman which served as haptens for immunization. In these soman analogs the chemically active P-F bond of the soman molecule was substituted by a P-OH group (which is ionized to P-O- under physiological conditions) or a P-H bond, creating compounds which we have named GDOH and GDH, respectively. These soman analogs were linked to carrier proteins through a short linker extending from the pinacolyl group. Monoclonal antibodies were selected according to their ability to bind to the immunizing hapten, and their specificities were determined by competitive inhibition assays. Out of total of 103 anti-GDOH antibodies 22 bound soman, whereas no binding was achieved with 62 anti-GDH antibodies. The two groups of monoclonal antibodies differed also in their structural specificity as demonstrated by different reactivities against a variety of soman analogs and substituted derivatives. These studies indicate that in order to achieve further improvement in anti-soman reactivity with protective potential, other groups (which resemble the OH group) have to be substituted for the F atom in the soman molecule.

Animals↗
PubMedDate not supplied

Expression and characterization of recombinant single-chain Fv and Fv fragments derived from a set of catalytic antibodies.

The generation of catalytic antibodies should enable the catalysis of reactions for which no enzymatic or chemical catalyst is currently available. In previous studies, we established a series of catalytic antibodies capable of hydrolysing p-nitrobenzyl (pNB) and p-nitrophenyl (pNP) esters. A group of these catalytic antibodies exhibited high reactivity and substrate specificity, yet each individual antibody demonstrated different kinetic parameters. In order to study the molecular basis for these differences, we have cloned, sequenced and expressed the variable regions of this group of antibodies as functional scFv and Fv in bacteria. The variable region of the heavy chain is derived from a novel germline gene of the J558 family whereas the light chain comes from a germline gene previously found in our catalytic antibodies catalysing the hydrolysis of only nitrophenyl esters, demonstrating that the heavy chain determines the specificity for the nitrobenzyl esters. Several different expression systems were examined for their ability to produce catalytically active antibodies. When expressed as an scFv, both refolded and secreted scFvs exhibited catalytic activity although yields of expressed protein were low. The secreted scFvs had higher specific activity. On the other hand, Fv fragments were expressed in sufficient quantities to allow kinetic analysis. Levels of expression were dependent on the sequence of VL used. Using this expression system, the relative contributions of the individual light and heavy chains to catalysis and binding could be evaluated. Both original VH and VL regions are required for hapten binding, although the VH is more crucial for catalysis. By replacing the CDR3 of the heavy chain with a random sequence, it was shown to be essential for both binding and catalysis. This expression system together with site-directed mutagenesis should enable a more detailed study of the catalytic mechanism of this set of antibodies.

Amino Acid Sequence↗
PubMedDate not supplied

Variability and repertoire size of T-cell receptor V alpha gene segments.

The immune system of higher organisms is composed largely of two distinct cell types, B lymphocytes and T lymphocytes, each of which is independently capable of recognizing an enormous number of distinct entities through their antigen receptors; surface immunoglobulin in the case of the former, and the T-cell receptor (TCR) in the case of the latter. In both cell types, the genes encoding the antigen receptors consist of multiple gene segments which recombine during maturation to produce many possible peptides. One striking difference between B- and T-cell recognition that has not yet been resolved by the structural data is the fact that T cells generally require a major histocompatibility determinant together with an antigen whereas, in most cases, antibodies recognize antigen alone. Recently, we and others have found that a series of TCR V beta gene sequences show conservation of many of the same residues that are conserved between heavy- and light-chain immunoglobulin V regions, and these V beta sequences are predicted to have an immunoglobulin-like secondary structure. To extend these studies, we have isolated and sequenced eight additional alpha-chain complementary cDNA clones and compared them with published sequences. Analyses of these sequences, reported here, indicate that V alpha regions have many of the characteristics of V beta gene segments but differ in that they almost always occur as cross-hybridizing gene families. We conclude that there may be very different selective pressures operating on V alpha and V beta sequences and that the V alpha repertoire may be considerably larger than that of V beta.

Animals↗
PubMedDate not supplied

Transfer of chimeric receptor gene made of variable regions of tumor-specific antibody confers anticarbohydrate specificity on T cells.

The antitumor specificity of T cells can be induced by gene transfer using a recently developed therapeutic approach (T body). In this work, we genetically conferred anticarbohydrate specificity onto T cells using the variable regions of monoclonal antibody MLuC1, which binds the Lewis(Y) (LeY) tumor-associated antigen that is overexpressed on several human carcinomas. The variable regions of MLuC1, which are in a single-chain Fv (ScFv) configuration, were cloned and spliced in a eukaryotic expression vector with both the gene encoding the signal-transducing gamma-chain of the human Fcgamma receptor and a flexible hinge domain. The chimeric ScFv-gamma gene was expressed in a murine cytotoxic T-cell hybridoma. Transfectants receiving vector only served as a negative control (mock). Screening for functional transfectants was carried out using a tumor growth inhibition assay. The soluble form of MLuC1 ScFv was recovered from bacteria periplasm and tested for binding to LeY-expressing cells by the fluorescence-activated cell sorter analysis. Despite the low binding ability of the soluble MLuC1 ScFv, 7 of 13 genetically engineered cytotoxic T lymphocyte clones inhibited the growth of LeY-positive cells and did not affect growth of LeY-negative cells. None of the mock clones tested specifically inhibited tumor growth. These data indicate that, by chimeric MLuC1 ScFv-gamma gene transfer, it is possible to confer anticarbohydrate specificity onto T cells and extend the applicability of the T-body approach to tumor-associated antigens that are naturally not recognized by T cells.

Amino Acid Sequence↗