Biomedical subjects

E Tzehoval

Publications and source records attributed to E Tzehoval.

At least 19 recordsLinked to original sources

PubMed1997

Tuftsin-THF-gamma 2 chimeric peptides: potential novel immunomodulators.

Synthesis of two chimeric peptides composed of tuftsin and thymic humoral factor-gamma 2 (THF-gamma 2) conjugates was accomplished. Our goal was the generation of novel immunomodulators. Initially, we demonstrate an IL-6 inducing activity of the phagocytic cells stimulant, tuftsin, on murine macrophages. This activity was documented only in the presence of antigen, either KLH or lysozyme. The augmentation was dose dependent, with optimal activity at a concentration of 200 and 20 nM, respectively. The chimeric peptides, either H2N-tuftsin-THF-gamma 2-OH or H2N-THF-gamma 2-tuftsin-OH, were also evaluated in the IL-6 system in the presence of the more potent antigen, KLH. The IL-6 inducing effect was maintained, although maximal activity appeared only at a concentration an order of magnitude greater than that of tuftsin. The chimeric peptides were further tested in an assay evaluating enhancement in murine bone marrow myeloid colony formation, a system in which THF-gamma 2, a T cell stimulant, has an established beneficial effect. The compounds were found to be inactive at the 25-200 ng/ml (14-112 nM) concentration range evaluated. Finally, the chimeric peptides were tested in a combined macrophages-T cells assay, i.e. antigen presentation, in which H2N-tuftsin-THF-gamma 2-OH was found to be more active than either parent peptide, thus representing a possible therapeutic agent.

Adjuvants, Immunologic↗

PubMed1996

1-Aminocyclobutanecarboxylic acid derivatives as novel structural elements in bioactive peptides: application to tuftsin analogs.

Four novel 2,4-methano amino acids (MAAs, 1-aminocyclobutane-1-carboxylic acids) were synthesized. These include the basic MAA analogs of lysine (16), ornithine (5), and arginine (6) and the neutral methanovaline (22), related to proline. The above MAAs, as well as the MAA analog of homothreonine (7), were incorporated into the peptide chain of the immunomodulatory peptide tuftsin, Thr-Lys-Pro-Arg, known to enhance several biological activities mediated by phagocytic cells. The synthetic methano tuftsin analogs were assayed for their ability to stimulate interleukin-6 (IL-6) secretion by mouse peritoneal macrophages and for their stability in human serum toward enzymatic degradation. It was found that, at 2 x 10(-7) M, [MThr1]tuftsin (24) and an isomer of [MVal3]tuftsin (27a) were considerably more active than the parent peptide in augmentation of cytokine release. [MOrn2]Tuftsin (25) was equally potent. The analogs [MThr1]tuftsin (24) and [MOrn2]tuftsin (25), both pertaining to the proteolytically sensitive Thr-Lys bond of tuftsin, exhibited high resistance to enzymatic hydrolysis as compared to tuftsin. Using specific rabbit anti-tuftsin antibodies in a competitive enzyme-linked immunosorbent assay (ELISA) revealed that none of the MAA analogs can cross-react with tuftsin. It may indicate that the peptides assume global structures different than that of tuftsin.

Amino Acids↗

PubMed1995

The plasmacytoma growth inhibitor restrictin-P is an antagonist of interleukin 6 and interleukin 11. Identification as a stroma-derived activin A.

A stromal protein, designated restrictin-P, that specifically kills plasma-like cells was purified to homogeneity and shown to be identical with activin A. The specificity to plasma-like cells stemmed from the ability of restrictin-P/activin A to competitively antagonize the proliferation-inducing effects of interleukin (IL) 6 and IL-11. Restrictin-P further interfered with the IL-6-induced secretion of acute phase proteins by HepG2 human hepatoma cells and with the IL-6-mediated differentiation of M1 myeloblasts. A competition binding assay indicated that restrictin-P did not interfere with the binding of IL-6 to its receptor on plasma-like cells, suggesting that it may act by intervening in the signal transduction pathway of the growth factor. Indeed, concomitant addition of restrictin-P and IL-6 to cytokine-deprived B9 hybridoma cells was followed by sustained overexpression of junB gene until cell death occurred, while IL-6 alone caused a transient increase only. This altered response to IL-6 stimulation was accompanied by a moderate increase in STAT protein activation. Thus, in this study, we identified the plasmacytoma growth inhibitor, restrictin-P, as being activin A of stromal origin. It is shown that activin A is an antagonist of IL-6-induced functions and that it modifies the IL-6 signaling pattern.

Activins↗

PubMed1995

Combined vaccination with major histocompatibility class I and interleukin 2 gene-transduced melanoma cells synergizes the cure of postsurgical established lung metastases.

We have analyzed and compared in detail the malignant phenotypes of, the immune mechanisms induced by, and the immunotherapeutic potentials of B16-F10.9 melanoma cells manipulated by gene transfer to express syngeneic H-2Kb molecules or to secrete the cytokines interleukin 2 (IL-2) or IL-6. Local tumor growth in the footpad of transduced cells is mainly retarded by expression of H-2Kb and IL-2 genes and less by expression of IL-6. Mice given injections intrafootpad of tumorigenic doses of transduced clones manifested significantly reduced postsurgical spontaneous metastasis. After i.v. inoculation, mice given injections of F10.9-Kb expressors did not develop experimental lung metastases; mice given injections of F10.9-IL-6 secretors developed reduced metastatic loads; whereas mice given injections of F10.9-IL-2 secretors developed high loads of lung metastases. On the basis of injections into nude mice, in vivo depletions of CD4+, CD8+, and NK1.1+ cells, and in vitro CTL and natural killer (NK) assays, we show that all F10.9-modified cells induce CD8+ tumor-specific CTL activity and that F10.9-IL-2 secretors also induce nonspecific NK/lymphokine-activated killer cell activity. Vaccinations with F10.9-modified cells were capable of significantly reducing metastatic spread from small established F10.9 footpad tumors. However, in mice carrying preestablished lung metastases, a highly therapeutic effect was achieved only when H-2Kb expressors and IL-2 secretors were combined in vaccination, whereas individual vaccines or other combinations had marginal effects. This higher efficiency of the combined vaccine is due to the combined effect of efficient CTL induction and NK/lymphokine-activated killer cell activity as concluded from depletion of CD8+ and NK1.1 cells during immunotherapy. Thus, the cure of established metastasis can be achieved by the synergistic effects of vaccination with class I and IL-2-transduced tumor cells.

Animals↗

PubMed1995

Role of cytokines in termination of the B cell lymphoma dormant state in AKR mice.

The high incidence of spontaneous T cell lymphomas in AKR mice (affected by sustained viremia) can be greatly reduced by experimental manipulations including thymus removal at young age or by genetic manipulation changing the Fv-1 allele that controls replication and spread of viruses (establishing the congenic AKR.Fv-1b mice). Although T cell lymphomagenesis is prevented, all these mice were shown to carry endogenous ecotropic provirus-induced potential lymphoma cells (PLCs) in a dormant state. The termination of the dormant state, leading to a high incidence of CD5+ IgM+ B cell lymphomas, was triggered by interference with T cell functions (optimal effect observed following in vivo administration of anti-CD8 moAb), administration of T cell growth factors or by injecting the MCF-247 recombinant virus isolate (from AKR origin) that affects T cell functions. The assumption that the PLC dormant state is maintained through specific immunological mechanisms (involving T cells or antibodies recognizing PLCs) could not be substantiated experimentally. The results of the present studies suggest that T cells provide immunoregulatory signals or factors that contribute to the maintenance of the B cell lymphoma arrest and/or proliferation. Analysis of cytokine levels produced by splenocytes taken from mice during PLC dormancy or its breakdown indicated reduced levels of IL-2 and IL-4 and marked elevation of IL-1 and IL-6 associated with the termination of the dormant state. The effect of IL-1 and IL-6 on terminating the dormant state was demonstrated by injecting these cytokines into PLC carriers, thymectomized 12-month-old AKR mice, yielding 80-85% CD5+ IgM+ B cell lymphomas. The role of IL-6 on B cell lymphoma proliferation was also indicated in MCF-247 mediated termination of dormancy, by inhibiting significantly its effect via in vivo administration of anti IL-6 moAbs.

Aging↗

PubMed1994

[Decreased interleukin-1 and interleukin-2 production after splenectomy].

Production of interleukin-1 and of interleukin-2 was measured in 57 splenectomized patients. 11 of them were after elective operations (aged 14-37 years, mean 24) and 46 posttraumatic (aged 20-36, mean 23) and in 20 appropriate controls. There was significant reduction of both interleukins in the splenectomized group, more evident in the elective group. The deficiency was not related to age of patient or time since splenectomy. These results support the view that a consequence of splenectomy is immunoregulatory deficit.

Adolescent↗

PubMed1993

Anti-metastatic vaccination of tumor-bearing mice with IL-2-gene-inserted tumor cells.

IL-2 gene was introduced through retroviral vectors into the highly malignant and poorly immunogenic 3LL-D122 clone. Both high and low D122-IL-2 secretors showed elimination of tumorigenicity in syngeneic immune-competent mice; however, in nude mice only the high IL-2 secretor showed reduced tumorigenicity as compared with parental D122 cells. Also, following intravenous inoculation, only the high IL-2 secretor showed reduced generation of metastases, whereas the low IL-2 secretors were as highly metastatic as parental cells. These results seem to indicate that low levels of IL-2 secreted by tumor cells are sufficient to activate T cells, while higher levels are needed in order to activate non-T-cell effectors. D122-IL-2 secretors induced high levels of anti-tumor CTL, while their sensitivity to the lytic activity of these CTL was similar to the sensitivity of D122 cells, thus indicating that the elevation of immunogenicity of IL-2 secretors was essentially due to the secreted IL-2. In accordance with CTL induction, pre-immunization with IL-2 secretors protected mice against subsequent challenge of parental cells. Moreover, immunization in an "immunotherapy protocol" i.e., vaccination of mice carrying an established tumor of parental D122 cells with inactivated D122-IL2 infectants, almost completely eliminated the generation of lung metastases by D122 cells, thus providing a rationale for the use of IL-2 gene transferred tumor cells as a modality for treatment of metastasis.

Animals↗

PubMed1993

Pyknodysostosis: imaging and laboratory observations.

Pyknodysostosis is a rare form of sclerosing bone dysplasia with autosomal recessive inheritance. Affected members of two families were assessed as follows: three patients underwent densitometry measurements and bone scans; four patients underwent magnetic resonance imaging (MRI) and an immunological investigation, as well as a detailed endocrinological and biochemical laboratory review. Densitometry measurements revealed values of up to 291% of age-matched normal controls; this increased bone density was mainly in the trabecular bone and not in the cortical bone. The MRI showed the cortex to be of normal thickness, whereas the increase in trabecular bone limited the space within the medullary canal. Bone scans and single photon emission computerized tomography in three patients showed an increased uptake of [99mTc]methylene diphosphonate of up to 538% of age-matched controls, which reflected the increased bone density. Monocyte function tests demonstrated a normal phagocytic capacity, but their killing activity was impaired. Interleukin-1 secretion was also impaired, which may point to the pathogenesis of the disease, in view of its function as an osteoclast activator and its role in bone resorption.

Adolescent↗

PubMed1993

Immune cell defects affect bone remodelling in osteopetrotic op/op mice.

The aim of the present work was to further characterize immunological defects in osteopetrosis. The op/op mutant mouse is of particular interest since a marrow cavity develops spontaneously in older animals. The interleukin production (IL-1, IL-2, IL-3, IL-4, IL-6), the presence of macrophage differentiation antigens and the evolution of the bone lesions were studied in osteopetrotic and normal mice. Low levels of IL-1, IL-3 and IL-4 were observed at the age of 6 weeks in the op/op mice. However, at 22 weeks of age, the level of IL-1 and IL-4 returned to normal value in these op/op mice whereas the level of IL-3 remained partially decreased at the same age. Furthermore, macrophage expression of MAC-2 antigen, reduced at 12 weeks of age was found to be normal 10 weeks later. These immunological defects and their recovery seems to be concomitant with the healing of the bone lesions.

Animals↗

PubMed1993

Synthesis and biological activity of [L-hydroxyproline]3-tuftsin analogue and its alpha- or beta-O-D-glucosylated derivatives.

Syntheses are described of the Hyp3-tuftsin analogue and of its derivatives alpha- or beta-O-glycosylated at the side chain function of the hydroxyproline residue. The carbohydrate-free tetrapeptide was prepared by reacting Z-Thr-Lys(Z)-OH with H-Hyp-Arg(NO2)-OBzl by the mixed anhydride procedure. In the synthesis of the alpha-glycosylated analogue the O-glycosyl amino acid was incorporated by reacting Boc-(Glc alpha+beta)Hyp-OH with H-Arg(NO2)-OBzl through the same procedure. The alpha-glucosylated dipeptide was isolated from the diastereomeric mixture, selectively deblocked, and acylated with Z-Thr-Lys(Z)-OH by the mixed anhydride procedure. In the preparation of the beta-glucosylated analogue the BOP procedure was used for reacting Boc-[Glc(Ac)4 beta]Hyp-OH with H-Arg(NO)2-OBzl was well as for the final coupling to tetrapeptide. Removal of protecting groups from crude tetrapeptides was achieved by catalytic hydrogenation. Deacetylation of the sugar moiety of the beta-glucosylated tetrapeptide was achieved by treatment with sodium methoxide in methanol. The synthetic compounds were isolated by ion exchange chromatography, and characterized by elemental analysis, amino acid analysis, optical rotation and proton NMR. Their capacity to evoke the release of interleukin 1 from mouse peritoneal macrophages and to modulate immunogenic activity of antigen-fed cells was evaluated, in comparison with tuftsin and rigin. All of the analogues were found to possess tuftsin-like activity.

Amino Acid Sequence↗

PubMed1993

Immunotherapy via gene therapy: comparison of the effects of tumor cells transduced with the interleukin-2, interleukin-6, or interferon-gamma genes.

We have comparatively analyzed the immune mechanisms induced by and the immunotherapeutic potentials of a highly metastatic clone of the Lewis lung carcinoma, D122, transduced with the interleukin-2 (IL-2), IL-6, or interferon-gamma (IFN-gamma) genes. All of the D122 cytokine gene-transduced cells induced antitumor CD8+ cytotoxic T lymphocytes (CTLs), as can be judged from in vivo depletion of CD8+ cells and in vitro CTL assays. In vivo depletion of CD4+ cells did not affect the malignant phenotypes of the different D122 gene-modified cells, but in vivo depletion of natural killer (NK) cells resulted in increased malignancy of both D122 cells and D122 gene-modified cells. In accordance with the effects of in vivo NK depletion, D122 as well as D122 derivative cells were sensitive to lysis by polyinosinic-polycytidylic acid (poly I:C)-induced activity. We discuss the immune responses generated by the different D122 gene-modified cells in view of their in vivo behavior in syngeneic and nude mice. We also performed comparative analysis of the capacity of vaccinations with irradiated D122 gene-modified cells to cure established micrometastases of parental D122 cells in tumor-operated mice. Vaccinations with D122-IL-2 or -IL-6 secretors did not generate a significant effect. Also, vaccinations with D122-IFN-gamma cells, which showed increased major histocompatibility complex class I expression but did not secrete detectable levels of IFN-gamma, did not cure established micrometastases. Only vaccination with D122-IFN-gamma high secretors efficiently cured postoperated mice carrying established micrometastases. We discuss the relevance of these results to the application of immunotherapy via cytokine gene therapy of human malignancy.

Animals↗

PubMed1992

Interleukin 6 gene transfection into Lewis lung carcinoma tumor cells suppresses the malignant phenotype and confers immunotherapeutic competence against parental metastatic cells.

To investigate the influence of interleukin 6 (IL-6) production on malignancy of tumor cells we transfected cells of the high-metastatic, low-immunogenic D122 clone of the Lewis lung carcinoma with a mammalian expression vector containing the human IL-6 complementary DNA. In vitro, IL-6 positive transfectants showed growth inhibition that was directly correlated with the levels of IL-6 production. The in vitro growth arrest did not seem to be a function of an autocrine system mediated via the secreted human IL-6 acting on the tumor cell surface receptors since neutralizing antibodies to human IL-6 did not prevent the growth inhibition. Neither did exogenous human recombinant IL-6 affect the growth of D122 cells. In vivo, IL-6 positive transfectants showed reduction of tumorigenicity and significant suppression of metastatic competence in syngeneic, immunocompetent mice. In mature T-cell deficient nude mice, the IL-6 transfectants showed some arrest of local growth but no suppression of lung metastasis. It seems therefore that the reduction of metastatic competence of IL-6 transfectants is primarily a function of stimulation by the transfectants of host T-cell immune responses. Immunization with inactivated high-positive IL-6 transfectants induced high levels of anti-tumor cytotoxic T-lymphocytes and protected mice against metastatic growth of a subsequent graft of parental tumor cells. Moreover, reduction of metastatic growth of parental highly metastatic D122 cells was also achieved when immunization of mice was begun after establishment of the primary parental tumors. Thus, inactivated IL-6 transfectants were effective when used as a cellular vaccine for experimental immunotherapy of metastasis.

Adolescent↗

PubMed1992

Dynamic changes in cytokine secretion by stromal cells during prolonged maintenance under protein-free conditions.

Stromal cells of bone marrow origin produce a variety of known cytokines and some factors exhibiting apparently new biological activities. Several of these were identified by the study of cell to cell interactions and were not found in detectable amounts in media conditioned by the cells. We describe here a culture system that enables the release of stromal cytokines into medium free of any added proteins and supplemented with peptides from casein hydrolysate (0.1%). The absence of serum proteins allows extensive concentration and monitoring of activities that are otherwise undetectable. Stromal cells of the MBA-2.1 clonal cell line were seeded in a stationary bed reactor packed with a carrier of non-woven fabric matrix. After a proliferation phase with serum containing medium, the cells were maintained for over 10 months in protein-free medium. Throughout this extended incubation in the absence of serum or serum replacing proteins, stromal cells retained their viability and continuously released transforming growth factor-beta (TGF-beta), macrophage-colony stimulating factor (M-CSF) and restrictin-P, a cytotoxic factor that specifically arrested the growth of plasmacytoma cells. In addition, interleukin-6 (IL-6) was first undetectable, and later in culture its titer reached a maximum of 180,000 international units (IU)/ml. Concomitantly, the production of restrictin-P diminished and reached its lowest levels at the end of 10 months. The results may imply a possible causal relationship between the expression of IL-6 and restrictin-P, since no similarly significant changes were observed in the titers of M-CSF and TGF-beta. This novel bioreactor system may be adaptable for efficient production of different cytokines under absolute serum-free conditions.

Animals↗

PubMed1991

Glyco-tuftsin derivatives modulate interleukin-1 and tumor necrosis factor production.

Six Thr1 (O-glyco)-derivatives of the "phagocytosis stimulating peptide" tuftsin, H-Thr-Lys-Pro-Arg-OH and the N-glycosylated undecapeptide H-Thr-Lys-Pro-Arg-Glu-Gln-Gln-Tyr-Asn(beta-D-GlcNAc)-Ser-Thr-OH, which correspond to the "tuftsin-region" at the Fc-domain of immunoglobulin G (amino acid residues 289-299), were evaluated in comparison with tuftsin and rigin, H-Gly-Gln-Pro-Arg-OH, for their capacity to evoke the release of interleukin-1 and tumor necrosis factor from mouse peritoneal macrophages and from human monocytes. Several glycosylated tuftsin derivatives were found to modulate, in a rather dose-dependent manner, the release of the two cytokines from both cell types.

Amino Acid Sequence↗

PubMed1990

Polytuftsin: a potential precursor for slow release of the phagocytosis stimulating peptide tuftsin.

1. Polytuftsin (Thr-Lys-Pro-Arg)n, was synthesized through polycondensation of an amino-free and carboxyl-activated derivative of tuftsin, H2N-Thr-Lys(Z)-Pro-Arg(Tos)-OSu, following suitable deprotection and fractionation steps. 2. Digestion of polytuftsin by trypsin, as well as by normal human serum, at 37 degrees C, yielded free tuftsin. 3. Polytuftsin affected the decreased formation of lung-metastasis, in B16 melanoma treated mice and prolonged the survival of animals more efficiently than tuftsin. 4. Tuftsin was found to be totally degraded by serum enzymes within approximately 60 min at 37 degrees C.

Amino Acid Sequence↗

PubMed1989

Immunogenic capacity of macrophage hybridomas.

Two clones, E2-7.7 and E2-10.50, derived from two macrophage(M phi)hybridomas, E2-7 and E2-10, have been studied. The first clone, E2-7.7, is Ia+ and Fc receptor (FcR) negative and manifests a strong antigen-presenting capacity. When we pulsed its cells in vitro with keyhole limpet hemocyanin (KLH) antigen and injected them into syngeneic animals, we found that as small a dose as 10(3) cells initiated an immune response in vivo. On the other hand, antigen-pulsed cells of the E2-10.50 clone, which are Ia- and FcR+, were almost incapable of triggering immunity, even when injected at a dose of 10(5) cells. Thus, the two clones differ in their immunogenic capacity (both cellular and humoral immunity). In experiments aimed at testing the stimulation in vitro of primed lymph node (LN) cells by antigen-pulsed cells of these two hybridoma clones, we observed that E2-7.7 stimulated the unfractionated population of LN cells and the LN-derived population of T cells. The E2-10.50 cells stimulated only the unfractionated population of LN cells, but not the T cell population. Subsequent tests indicated that the E2-10.50 cells require an intermediate Ia+ accessory cell to present the antigen to the T lymphocytes. Analyzing the molecular structure of the M phi hybridomas, we discovered that major histocompatibility complex (MHC) genes of the myeloma haplotype (H-2d), and of the splenic M phi used for fusion (H-2k), which were not expressed in the parental myeloma or in the E2-10.50, were expressed in the E2-7.7. Thus, somatic cell fusion of M phi resulted in the activation of suppressed genes of the myeloma partner. It appears that these antigens participate in controlling the immunogenic properties of the E2-7.7 clone. Testing the effects of interferons on the M phi hybridomas, we observed that interferon-gamma activated, at both the mRNA and the cell surface-antigen levels, the expression of H-2Dk, H-2Kd and H-2Dd in the E2-10.50 cells, but not in the E2-7.7. Consequently, interferon-gamma augmented significantly antigen presentation by E2-10.50 but not by E2-7.7 cells. These two hybridoma clones might represent two distinct subsets of normal M phi, manifesting two different sets of functional properties.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1989

Defective leukocyte fungicidal activity in end-organ resistance to 1,25-dihydroxyvitamin D.

Recent studies have shown 1,25(OH)2D3 receptor-mediated modulation of leukocyte proliferation, differentiation, and function. We examined the phagocytosis and killing of microorganisms by neutrophils and monocytes from five patients of three families with hereditary resistance to 1,25(OH)2D3. Phagocytosis of microorganisms by patients' neutrophils and monocytes was normal. However, defective neutrophil killing activity toward Candida albicans (30-40% of controls) was found in all patients. The killing of Staphylococcus aureus was normal. The neutrophil chemiluminescence, nitroblue tetrazolium (NBT) dye reduction, and the generation of superoxide ions and hydrogen peroxide by neutrophils and monocytes after induction by either soluble stimuli or zymozan particles, did not differ from those in controls. The neutrophil myeloperoxidase activity was also normal. Monocytes obtained from two patients of different families before long-term calcium infusion therapy and after they became normocalcemic, demonstrated a similar impaired fungicidal activity toward Saccharomyces cerevisiae, indicating that hypocalcemia itself was not the cause of the killing defect. However, the addition of the Ca+2 ionophore A23187 (1 microM) to the test medium restored the monocyte fungicidal activity to normal. As patients' neutrophil cytosolic free calcium concentration was similar to that in controls, it is suggested that 1,25-(OH)2D3 exerts its effect on leukocyte function by a putative receptor-mediated regulation of subcellular calcium localization which may be important for fungicidal activity.

Calcitriol↗

PubMed1989

Effect of anesthesia on the immune system: suppression of the immunogenic capacity of macrophages and of lymphocyte transformation.

Experiments were carried out aimed at investigating the effects of anesthesia without surgery on certain functional components of the immune system. We observed that the immunogenic antigen-presenting capacity of mouse peritoneal macrophages was significantly reduced one week post-anesthesia, with either injected or inhaled anesthetic drugs. On the other hand, an augmentation of the phagocytic activities of these macrophages was manifested. Hence, the impaired immunogenic potency could not be attributed to a reduced antigen uptake. Lymphocyte transformations, i.e., response to PHA and Con A were suppressed, whereas the response to LPS was augmented.

Anesthesia↗