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D Naor

Publications and source records attributed to D Naor.

At least 37 records · Page 2Linked to original sources
PubMed1994

Beta 2-integrin dependent aggregate formation between LB T cell lymphoma and spleen cells: assessment of correlation with spleen invasiveness.

LB is an aggressive T cell lymphoma which rapidly invades the spleen and lymph nodes of BALB/c mice after s.c. inoculation. We previously reported that mAb directed against the beta 2 chain of the leukocyte function-associated antigen-1 (LFA-1) adhesion molecule (CD18) blocked the invasion of LB cells into the spleen but not into the lymph nodes. The same antibody also blocked in vitro aggregate formation between normal spleen cells and LB cells. However, aggregate formation between normal lymph node cells and LB cells was not detected, regardless of ratio. In an attempt to evaluate the association between aggregate formation and tumor invasion of the lymphoid organs, we have now extended the study. Intravenous injection of anti-CD18 mAb, which blocked spleen invasion by LB cells, also blocked the formation of ex vivo aggregates, spontaneously generated in spleen, but not in lymph node, cell suspensions of BALB/c mice s.c. inoculated with LB cells. In contrast, mAbs unable to block spleen invasion were ineffective inhibitors of both in vitro and ex vivo aggregate formation between spleen and LB cells. Spleens of nude mice that did not provide a supportive environment for lymphoma invasion, were also deficient in target cells forming aggregates with LB cells. In line with this observation, enriched T cells formed more aggregates with LB cells than did enriched non-T cells, indicating the lymphoma's preferential binding to splenic T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Blocking lymphoma invasiveness with a monoclonal antibody directed against the beta-chain of the leukocyte adhesion molecule (CD18).

The same integrin adhesion molecules used by normal leukocytes for traffic and localization in inflammation sites may be used by malignant cells for dissemination. Identifying the adhesion molecules and then blocking them with appropriate antibody may therefore prove useful for controlling tumor spread. This prediction was tested on a spontaneous murine T cell lymphoma (LB) that expresses LFA-1 adhesion molecules. The adhesion molecules were identified by fluorocytometry and immunoprecipitation with anti-CD18 mAb (M18/2). Subcutaneously inoculated LB lymphoma rapidly infiltrated the spleen and the lymph nodes, as indicated by histologic examination and [3H]thymidine incorporation assay of proliferating LB cells derived from the invaded organs. The normal organization of the lymphoid organs was totally effaced by the infiltrating LB cells. Intravenous injection of anti-CD18 mAb, protein G-purified anti-CD18 mAb, or its F(ab')2 fragments (but not irrelevant control mAb) blocked the invasion of the s.c. inoculated lymphoma into the spleen. Whereas i.v. injected anti-CD18 mAb could not block the infiltration of LB cells into the lymph nodes, local s.c. injection of this antibody near the lymph nodes partially inhibited lymphoma invasion into these organs. It was further found that LB cells form aggregates with spleen cells but not with lymph node cells. In addition, spleen-infiltrating LB cells invade both the spleen and the lymph nodes after s.c. injection. On the other hand, lymph node-infiltrating LB cells invade mainly the lymph nodes under similar circumstances.

Animals↗
PubMed1993

Insulin dependence of murine T-cell lymphoma. II. Insulin-deficient diabetic mice and mice fed low-energy diet develop resistance to lymphoma growth.

Physiological concentrations of insulin support the in vitro growth of LB T-cell lymphoma. We could not detect similar insulin dependence in other tumor cell lines. This study reports that insulin also enhances the growth of LB cells in vivo. Mice treated with Streptozotocin (SZ) developed partial resistance to LB lymphoma growth and they survived longer (p < 0.0025) than non-diabetic mice after LB-cell inoculation. A few diabetic mice developed complete tumor resistance, manifested by total regression of the lymphoma. SZ-treated diabetic mice reconstituted with external insulin died as fast as non-diabetic mice when both were inoculated with the same number of LB cells. The SZ-treated diabetic mice did not develop resistance to the growth of BCLI B-cell leukemia, which demonstrated only a marginal proliferative response to insulin in vitro. Mice fed a low-energy diet exhibited low insulin levels and also developed resistance to lymphoma growth (50% survival 21 days vs. 15 days; p < 0.0005), supporting the concept that insulin enhances LB T-cell tumor development in mice.

Animals↗
PubMed1992

Insulin dependence of murine lymphoid T-cell leukemia.

The in vitro proliferation of the spontaneous lymphoid T-cell leukemia designated LB was enhanced by physiological, intermediate and supraphysiological concentrations of insulin. The enhancing effect was observed in both serum-free medium (SFM) and medium containing low concentrations of serum. Guinea-pig anti-insulin serum, but not guinea-pig normal serum, inhibited the proliferation of LB cells incubated either in medium containing serum alone or in medium containing serum and supplemented with insulin. This finding suggests that LB cells use serum insulin as a growth factor. Insulin-like growth factors I (IGF-I) and II (IGF-II) failed to stimulate an appreciable proliferation in LB cells, whereas in the same experiment insulin markedly enhanced the proliferation of this lymphoid leukemia. Furthermore, the concentration of unlabelled insulin required to displace 50% of 125I-insulin bound to LB cells was 3 orders of magnitude lower than the concentration of IGF-I required to achieve the same displacement. Our findings indicate that interaction of insulin with its own receptor, and not with IGF-I receptor, triggers the proliferation of LB cells. Radio-receptor assays revealed that LB cells express approximately 3,200 molecules of high affinity (Kd = 10(-9) M) insulin receptor per cell. None of 7 other tumor cell lines tested responded to insulin. The proliferation of insulin-stimulated LB cells was also inhibited with tyrphostin, a tyrosine kinase blocker analogous to tyrosine, which perhaps blocks the tyrosine kinase activity of the insulin receptor beta-chain.

Animals↗
PubMed1992

Experimental model of autoimmune hemolytic anemia induced in mice with levodopa by intraperitoneal injection or oral feeding.

In this paper we describe a murine experimental model of autoimmune hemolytic anemia induced with multiple injections or oral feeding of levodopa. Strain A mice were intraperitoneally injected or fed with levodopa, at a dose equivalent to the one used in human therapy, and subsequently they developed cycles of IgM, IgG and IgA anti-mouse red blood cells (MRBC) autoantibody responses. Levodopa injection induced serum IgM and IgG anti-MRBC responses and levodopa feeding enhanced the serum anti-MRBC IgA response. The appearance of autoantibodies in the serum was followed by binding of the autoantibodies to mice erythrocytes and three phases of anemia. Red cell bound IgM and IgG autoantibodies were predominant in levodopa-injected mice whereas red cell bound IgA autoantibodies were predominant in levodopa-fed mice. The specificity of the serum IgA autoantibody was not restricted since it interacted with erythrocytes of various species.

Administration, Oral↗
PubMed1991

Regulatory interactions among autologous T cell clones. Human bifunctional T cell clones regulate the activity of an autologous T cell clone.

In contrast to the ease of cloning and characterizing, at the molecular level, helper and cytotoxic T cells, suppressor T cells remain an enigma, and their existence as discrete entities is being increasingly challenged. Here we review evidence that CD4+ regulatory clones, capable of expressing both helper and suppressor functions, may account for much of the suppressor function. It is suggested that a single T cell clone, depending on the signals it receives from its environment, may release either helper or suppressor cytokines. Studying such clones under defined conditions (providing suppressor signals), may preclude detection of their helper capacity. Since some therapeutic approaches in various human diseases are based on the manipulation of helper and suppressor functions, the question whether committed suppressor cells exist has important practical implications in medicine.

Clone Cells↗
PubMed1991

Inflammatory response induced with an isolated syngeneic activation antigen shared by normal lymphoblasts and YAC lymphoma cells.

An immunogenic protein with an identical Mr (64 kDa) was isolated from syngeneic concanavalin A-induced lymphoblasts (syn-Con A-blasts) and YAC lymphoma cells, both derived from A mice. The 64-kDa protein was purified by a sequence of biochemical steps: Sephadex G-100 gel filtration, ion-exchange chromatography in a fast protein liquid chromatography system, Con A-Sepharose affinity chromatography, and preparative gel electrophoresis. The immunogenic fraction isolated in each step was moved to the next one, and so on. The immunogenicity of the separated fractions was measured by a lymph node proliferation (LNP) assay, which is indicative of a delayed-type hypersensitivity response. For instance, the final 64-kDa isolated protein of the syn-Con A-blasts induced an efficient LNP response in A mice which was detected after challenge with the final 64-kDa isolated protein of YAC cells. In addition to their identical molecular weight, both proteins were eluted at the same ionic strength and both expressed affinity to Con A-Sepharose beads, suggesting that they were glycosilated. Similar 64-kDa proteins were isolated by a different purification procedure, which was performed in the presence of protease inhibitors, excluding the possibility that the final antigen was an autodigested product. As the 64-kDa protein is immunogenic in the syngeneic host, it may be employed as a immunotherapeutic reagent against the original tumor and perhaps against other tumors expressing the same antigen.

Animals↗
PubMed1990

Murine spontaneous T-cell leukemia constitutively expressing IL-2 receptor--a model for human T-cell malignancies expressing IL-2 receptor.

We describe a new, spontaneously occurring BALB/c-derived murine T-cell leukemia. The leukemic cells, designated LB, grow rapidly and progressively in the syngeneic host with no signs of effective immunological resistance. LB cells expressed the Thy-1+, Lyt-2+, L3T4-, CD3- class-I+, CD25+ (IL-2 receptor, IL-2R), class-II-, gp70- phenotype. As LB cells express IL-2, as indicated by staining with 2 distinct anti-CD25 IL-2R monoclonal antibodies (MAbs), the therapeutic efficacy of IL-2-diphtheria toxin-related protein was tested on this leukemic model. IL-2-diphtheria toxin, but not diphtheria toxin, efficiently inhibited the proliferation of LB cells. The proliferation of a murine myeloma cell line, which does not express IL-2R, was not inhibited by IL-2-diphtheria toxin. The possible implantation of this animal model in fundamental and practical studies is discussed.

Animals↗
PubMed1990

Interactions between autologous T cell clones.

A human CD4 clone (Mx9/9) using the V beta 8 receptor was used as antigen to generate autologous clones (termed anti-Mx9/9 clones) which proliferate in response to this clone, but not other autologous clones. This was used as an experimental model to explore the specific interactions between autologous T cells. Anti-HLA-DR monoclonal antibodies inhibited the response of the anti-Mx9/9 clones, suggesting that these clones recognize their target antigen in association with HLA-DR. Because of the specificity of the anti-Mx9/9 clones for the initiating clone (Mx9/9), but not any other autologous V beta 8- or V beta 8+ CD4 clones, the target antigen seems to be part of the T cell receptor, but not V beta 8 itself. However, the anti-Mx9/9 clones responded also to the autologous EBV line, and thus the target antigen is not known. The regulatory activity of the anti-Mx9/9 clones was assayed by coculture with their target clone. A variety of responses were seen, both inhibitory and stimulatory, which varied depending on the "conditions" of the T cell used. These results suggest that T cells interact in a complex network, perhaps as complex as the regulatory interactions between antibody molecules and B cells.

Antibodies, Monoclonal↗
PubMed1990

The reaction against autologous lymphoblasts as an indicator of lymphocyte hyperreactivity in rheumatoid arthritis.

We have previously found that there is a considerable variation in the responses of lymphocytes of normal individuals to autologous pokeweed mitogen (PWM)-induced lymphoblasts (PWM.AMLR) under completely autologous conditions. Having proposed that the reaction might measure an innate sensitivity for B cell hyperreactivity, we measured the PWM.AMLR of a normal group (8/18 positives) and a group of patients with rheumatoid arthritis (RA; 24/25 positives). Responses of the RA group were in general an order of magnitude greater than those of normal controls that generated positive responses, and the responding cells could clearly be shown to be both CD4-bearing and CD8-bearing T cells. T cell-independent B cell mitogen-induced (staphylococcus A) lymphoblasts derived from RA patients were capable of strongly stimulating autologous responder cells, while similarly treated cells of normal controls induced small responses. The staphylococcus A responses were smaller in general than those induced by PWM-induced lymphoblasts. These results support previous results that the degree of activation of both T cells and B cells determines the size of response in the autologous PWM.AMLR and that the PWM.AMLR may be used to determine differing degrees of the in vivo priming of these cells and their relation to clinical lymphocyte hyperreactivity.

Adult↗
PubMed1990

Specific interactions between a human CD4+ clone and autologous CD4+ bifunctional immunoregulatory clones.

The cellular communications between a human CD4+ clone and autologous CD4+ clones induced with the first clone are described. The autoreactive clones proliferated after stimulation with the inducer clone, but not after stimulation with autologous clones expressing irrelevant specificities. The inducer clone markedly lost its ability to interact with the autoreactive clones after the modulation of its T-cell receptor. The proliferation of the autoreactive clones stimulated with the inducer clone was blocked by anti-DR monoclonal antibody. Collectively, these findings indicate that the autoreactive clones recognize idiotypic-like determinants on the receptor of the inducer clone in conjunction with DR antigen. The regulatory activity of the autoreactive clones was assayed by co-cultivation with their target inducer clone. The autoreactive clones were not committed to a single program, they could either suppress or enhance the proliferation of the target cells depending on the state of activation of the target cells. Activated target cells were suppressed whereas non-activated cells were enhanced. It is predicted that antagonistic cytokines released from the autoreactive clones exert differential effects on the target clone.

Animals↗
PubMed1989

Experimental model of autoimmune hemolytic anemia induced in mice with levodopa.

This paper describes an experimental model of autoimmune hemolytic anemia induced with multiple injections of levodopa. The serum antibodies were detected by indirect enzyme-linked immunosorbent assay (ELISA) and autoantibodies bound to syngeneic erythrocytes were detected by direct ELISA. A strain of mice injected with levodopa, at doses which are approximately equivalent to those used in human therapy, developed early and late cycles of IgM and IgG anti-mouse red blood cell (MRBC) autoantibody responses. These responses were followed by binding of IgM and IgG autoantibodies to the syngeneic erythrocytes and by two phases of anemia. Different strains of mice exhibited different sensitivities to Levodopa treatment, suggesting that genetic factors affect the anti-MRBC autoantibody response to levodopa. Indirect ELISA revealed that mice subjected to both X-irradiation (250 rad) and levodopa treatment had higher levels of IgG anti-MRBC autoantibodies than mice subjected to levodopa treatment alone, suggesting that a radiosensitive suppressor mechanism controls the autoantibody response. The autoantibodies induced with levodopa exhibited an unrestricted specificity and retained significant activity after absorption of MRBC. Serum autoantibodies were also detected by indirect ELISA in the sera of normal mice. This "natural" autoimmunity was mouse strain dependent and was possibly further influenced by environmental factors. The various implications of this model of autoimmune hemolytic anemia are discussed.

Anemia, Hemolytic, Autoimmune↗
PubMed1989

T-cell clone anti-clone interactions. Effects on suppressor and helper activities.

An experimental model of two interacting clones of T cells is described, which may be used for defining and exploring the T-cell immunoregulatory network. Mx9/9 is a CD4 clone bearing an antigen receptor recognized by the Mx9 anti-V beta 8 monoclonal antibody (MoAb). Anti-V beta 8 MoAbs activate and induce cell proliferation of this clone. Autologous clones were raised against Mx9/9 cells using the peripheral blood mononuclear (PBM) cells of the Mx9/9 clone donor (PBMjm). Some of these cloned anti-clone cells proliferated after stimulation with irradiated Mx9/9 cells, but not after stimulation with other autologous cloned T cells or heterologous PBM, suggesting that these clones recognize the T cell receptor (TCR) of the Mx9/9 cells. The proliferation of the Mx9/9 stimulated cloned anticlone cells was blocked by anti-class II MoAbs, indicating that the autoreactive clones recognize their target antigen in conjunction with HLA Class II products. The ability of clone Mx9/9 to proliferate after stimulation with anti-V beta 8 MoAb was inhibited when clone 121 cells were added to the cultures. However, clone 121 lost its suppressor function after 4 months in culture and instead gained the ability to enhance the proliferation of Mx9/9 cells in the presence of anti-V beta 8 MoAb. In contrast, clone 18 lacked suppressor activity at the early stage of the study but later acquired this function. We conclude that some autoreactive clones are not fully committed and may express more than a single function. Such cells cannot therefore be designated as 'suppressor cells', although they expressed suppressor potential at certain stages.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Use of an autologous reaction in vitro to assess contributions of T and B lymphocytes to immune hyperreactivity of atopics.

The in-vitro proliferation reaction of peripheral blood lymphocytes (measured by [3H]thymidine incorporation) to autologous pokeweed mitogen (PWM)-induced lymphoblasts (PWM-lymphoblast-stimulated autologous mixed leucocyte reaction, PWM.AMLR) was used as a measure of immune hyperreactivity for comparison of atopic with non-atopic individuals. Accordingly, 10/24 non-atopics responded in the PWM.AMLR, and 19/19 atopics reacting to inhaled allergens responded. Autologous stimulation was associated with release of mitogenic factors from the PWM-activated stimulating cells (2/15 non-atopics, 9/15 atopics). For non-atopics, stimulation delivered by staphylococcus A (SAC)-activated cells was similar to that delivered by PWM-induced cells, while in atopics, the SAC.AMLR was never more than 50% of the PWM.AMLR, indicating a possible T cell component. Separation by panning of the stimulation cells into lymphocyte subsets supported the notion that stimulation involved a cooperation between B and T4+ T cells. It is proposed that a positive PWM.AMLR is dependent upon an initial B cell activation followed by the PWM stimulus dependent upon a previous T cell activation, where atopics have more lymphocytes in an activated state than healthy non-atopics. Such a baseline priming may contribute to an innate sensitivity of atopics to environmental allergens.

Adolescent↗
PubMed1989

Auto-delayed-type hypersensitivity induced in immunodeficient mice with modified self-antigens. V. Cellular autoreactivity directed against self-H-2Dd subregion mediates the inflammatory responses.

X-irradiated (250 rads) A mice injected with syngeneic trinitrophenylated spleen cells (Syn-TNP-SC) developed syngeneic delayed-type hypersensitivity (Syn-DTH) after footpad challenge with syngeneic concanavalin A-induced lymphoblasts (Syn-Con A blasts), as indicated by footpad swelling and lymph-node proliferation assays. Genetic analysis with different recombinant strains of mouse revealed that the H-2Dd subregion restricts these immunological activities. A small immunogenic entity was isolated from Syn-TNP-SC extract by gel filtration and affinity chromatography with anti-Dd antibody. X-irradiated A mice injected with this antigen also generated inflammatory responses after challenge with Syn-Con A blasts. Analysis of the data obtained from the gel filtration and the affinity chromatography suggest that the Syn-DTH-stimulating antigen is a fragment of the H-2Dd heavy chain with a molecular weight (MW) of 5,000 to 10,000. This fragment does not contain TNP molecules or sugar moieties and neither does it express affinity for antibodies against class II products. Ltk-cells transfected with the H-2Dd gene also induced Syn-DTH in X-irradiated A mice, while the parent cells failed to stimulate such a response. Taken together these findings indicate that the selection process in the thymus is not absolute and T cells recognizing self-major histocompatibility complex (MHC) products do migrate from this organ to the periphery of the immune system. The possible biological significance of these autoreactive cells is discussed.

Animals↗
PubMed1988

Self-reactive delayed type hypersensitivity induced in mice by syngeneic lymphoblasts. II. Isolation of two distinct lymphoblast antigens, one of which reacts (or cross-reacts) with anti-H-2Dd monoclonal antibody.

X-irradiated (250 rad) or normal A mice injected with syngeneic concanavalin A-induced lymphoblasts (syn-Con A blasts) developed an inflammatory response in their footpads 24 to 72 h after injection of syngeneic lipopolysaccharide-induced lymphoblasts (syn-LPS blasts) into these tissues. This immunological activity was designated syngeneic delayed type hypersensitivity (syn-DTH), because T cells transferred the response to naive recipients. Analysis on Ultrogel or Sephadex G-50 columns revealed that a Con A-blast extract contains two syn-DTH-stimulating antigens: a small antigen (6000-7000) and a large antigen (apparent MW of 160,000-175,000). This conclusion held true even when protease inhibitors were included in the fractionation procedure. The approximate molecular weights of these antigens estimated by the gel filtrations were confirmed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The large lymphoblast syn-DTH-stimulating antigen contains carbohydrate residues but not products of the H-2 genetic region. The small antigen does not contain sugar moieties, but it expresses affinity to anti-H-2Dd monoclonal antibody. The immune response to the small antigen but not to the large antigen is genetically restricted at both the induction and the elicitation phases of the DTH. A strain of mice immunized with the small antigen generated syn-DTH after challenge with lymphoblasts of B10.T (6R) mice, which share the H-2Dd subregion with A mice but not the H-2K or the H-2I subregions. Fast protein liquid chromatography of the small antigen yielded a purified material which appeared as a single band after Coomassie staining of its gel electrophoresis.

Animals↗