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T Diamantstein

Publications and source records attributed to T Diamantstein.

At least 109 records · Page 6Linked to original sources
PubMed1988

Anti-interleukin 2 receptor monoclonal antibodies spare phenotypically distinct T suppressor cells in vivo and exert synergistic biological effects.

The therapeutic efficacies of ART-18, ART-65, and OX-39, mouse antibodies of IgG1 isotype recognizing distinct epitopes of the p55 beta chain of the rat IL-2-R molecule, were probed in LEW rat recipients of (LEW X BN)F1 heterotopic cardiac allografts (acute rejection in untreated hosts occurs within 8 d). A 10-d course with ART-18 prolongs graft survival to approximately 21 d (p less than 0.001). Therapy with ART-65, but not with OX-39, was effective (graft survival approximately 16 and 8 d, respectively). Anti-IL-2-R mAb treatment selectively spared T cells with donor-specific suppressor functions; the CD8+ (OX8+ W3/25-) fraction from ART-18-modified recipients, and primarily the CD4+ (W3/25+ OX8-) subset from ART-65-treated hosts conferred unresponsiveness to naive syngeneic rats after adoptive transfer, increasing test graft survival to approximately 16 and 45 d, respectively. Concomitant administration of ART-18 and ART-65 to recipient animals in relatively low doses exerted a strikingly synergistic effect, with 30% of the transplants surviving indefinitely and 50% undergoing late rejection over 50 d. These studies provide evidence that anti-IL-2-R mAbs selectively spare phenotypically distinct T cells with suppressor functions. The data also suggest that in vivo targeting of functionally different IL-2-R epitopes may produce synergistic biological effects.

Animals↗
PubMed1988

Interleukin 2 and a lactogen regulate proliferation and protein phosphorylation in Nb2 cells.

Cell proliferation and protein phosphorylation in response to activation of lactogenic and interleukin 2 (IL-2) receptors were studied in Nb2 cells, a rat T-lymphocyte cell line. Human growth hormone (hGH) and rat IL-2 stimulated Nb2-cell proliferation to approximately the same degree, and the actions of both mitogens were potentiated by phorbol 12-myristate 13-acetate (PMA). A monoclonal antibody specific for the rat IL-2 receptor inhibited the mitogenic actions of rat IL-2, but not those of hGH. Exposure of Nb2 cells to either mitogen for 2-3 h increased phosphorylation of an 18,600-Da protein and decreased phosphorylation of a 15,600-Da protein. PMA also inhibited phosphorylation of the latter protein, but, by itself, PMA did not stimulate phosphorylation of the 18,600-Da protein. Overall, the results suggest that hGH and IL-2 act through separate receptors to stimulate proliferation of Nb2 cells, and that some of the actions of both mitogens may be mediated, in part, through regulation of protein phosphorylation.

Antibodies, Monoclonal↗
PubMed1988

The human intermediate-affinity interleukin 2 receptor consists of two distinct, partially homologous glycoproteins.

In this report we demonstrate that the human intermediate-affinity-type interleukin (IL) 2 receptor (IL 2R) consists of two distinct glycoproteins designated H1 and H2, whereas the high-affinity IL 2R consists of three chains, H1, H2 and the light chain (L), the Tac antigen. They are neither linked by disulfide bridges to each other nor to the L chain. Similar to the L chain, H1 and H2 apparently carry intramolecular disulfide bonds. From affinity-labeled IL 2 intermediate-affinity receptor complexes, we deduced an apparent mol. mass of 70 kDa for H1 and of 75 kDa for H2 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and of 55 kDa for H1 and of 85 kDa for H2 in SDS-PAGE/urea. As demonstrated by limiting proteolysis, both glycoproteins display high homologies or even identity proximal to the IL 2-binding sites. The areas which are responsible for the striking differences between H1 and H2 in SDS-PAGE/urea are located distally to the IL2-binding site and, in contrast to the L chain, are protected from the action of exogenous proteases by the plasma membrane.

Cross-Linking Reagents↗
PubMed1988

Demonstration of two distinct forms of released low-affinity type interleukin 2 receptors.

The release of interleukin 2 (IL2)-binding proteins, derived from the 55-kDa low-affinity IL2 receptor (IL2R; L chain), has been observed for virtually all L chain-bearing cells in either humans, the mouse or the rat. Based on the characterization of the released human L chain as a molecule 10 kDa smaller than the cell surface receptor, either proteolytic cleavage or differential splicing of the L chain-encoding mRNA have been suggested as mechanisms underlying the receptor release. Combining affinity labeling of the L chain with 125I-labeled IL2 and immunoprecipitation with L chain-specific monoclonal antibodies applied for the detection of soluble mouse IL2R revealed the existence of two classes of soluble receptors, one being of the same size as cell surface expressed L chain, the other of 45-kDa apparent molecular mass. These findings raise the possibility of mechanisms of receptor release other than those discussed for human L chain.

Animals↗
PubMed1988

Phenotypical characterization of the cells invading pancreatic islets of diabetic BB/OK rats: effect of interleukin 2 receptor-targeted immunotherapy.

We investigated immunohistochemically the phenotypes of mononucleated cells invading pancreatic islets of diabetic BB/OK rats in comparison to the diabetes-resistant parental strain, and 12 and 120 days after a temporary treatment (10 days) with a monoclonal antibody (1 mg/kg b.w.) directed against interleukin 2 receptor (IL 2R) combined with a subtherapeutic dose of cyclosporin A (1.5 mg/kg b.w.). Using a panel of monoclonal antibodies (OX-19, OX-8, W3/25, KI-M2R, OX-6, OX-17, ART-18) and the alkaline phosphatase anti-alkaline phosphatase system to visualize the bound primary antibodies, we observed an even distribution of mononucleated cells across the endocrine pancreas at a "background" level when obtained from diabetes-resistant parental rat strain. Diabetic BB/OK rats, characterized by a moderate hyperglycemia and a marked decrease of pancreatic insulin content, displayed a remarkable accumulation of mononucleated cells in the endocrine pancreas. Morphometric studies revealed an increase of all phenotypes investigated, nearly all mononucleated cells expressed class II histocompatibility antigens (OX-6+, OX-17+) and the number of cells expressing the IL 2R (ART-18+) was markedly enhanced. Sixty-seven percent of the immunotherapeutically treated BB/OK rats normalized plasma glucose and enhanced pancreatic insulin content. The successfully treated animals are characterized by a decrease of cells invading pancreatic islets (OX-19+, OX-8+, W3/25+, KI-M2R+), a decrease of class II histocompatibility antigen and IL 2R expression. The number of IL 2R cells is also diminished in the endocrine pancreas of unsuccessfully treated BB rats.

Animals↗
PubMed1988

Reversal by interferon-gamma of inhibition of delayed-type hypersensitivity induction by anti-CD4 or anti-interleukin 2 receptor (CD25) monoclonal antibodies. Evidence for the physiological role of the CD4+ TH1+ subset in mice.

In mice, induction of delayed-type hypersensitivity (DTH) and of antibody formation to sheep red blood cells (SRBC) was inhibited by the anti-CD4 monoclonal antibody (mAb) GK1.5. However, anti-interleukin 2 mAb AMT-13 inhibited DTH response but not antibody formation. The inhibitory action of the mAb on DTH, but not an antibody formation, was reversed by concomitant injection of recombinant mouse interferon-gamma. These data provide the first in vivo evidence for the postulated physiological role of the CD4+ TH1 lymphocyte subset and indicate that the action of anti-interleukin 2 receptor mAb is restricted to this T helper subset.

Animals↗
PubMed1988

The high affinity interleukin 2 receptor: evidence for three distinct polypeptide chains comprising the high affinity interleukin 2 receptor.

Low and high affinity receptors for interleukin 2 were investigated on interleukin 2 (IL-2) receptor bearing cells by chemical cross-linking of 125I-labelled IL-2 to its receptor, or membrane proteins associated with the IL-2 binding sites. SDS-PAGE analysis of the cross-linked complexes of the murine CTLL 16 cells and human T-blasts, which bear high and low affinity IL-2 receptors, showed three distinct bands. The fastest of those three bands ran in parallel to the single band of 65-70 kDa found on the only low affinity receptor bearing mouse T-lymphoma Eb, which is thought to be one beta-chain (55 kDa IL-2 binding protein) and one IL-2. Both upper bands ran in parallel with those produced by the 2C8 clone of the NK-like cell line YT which lacks the 55 kDa binding protein and bears only a single class of receptors with an intermediate affinity. Internalisation studies using CTLL 16 cells revealed that all three bands disappeared under conditions allowing receptor internalisation. Low and high affinity binding sites of CTLL 16 cells were destroyed by trypsinisation and the IL-2 binding properties of the cells were regenerated in parallel with the reappearance of all bands. These results show in addition to the beta-chain (55 kDa binding protein) and the alpha-chain 75 kDa binding protein, an IL-2 membrane protein complex with an apparent mol. wt of 115 kDa in CTLL 16 cells. They are the first direct indication of a putative gamma-chain of the high affinity IL-2 receptor.

Animals↗
PubMed1988

Interleukin 2-dependent and interleukin 2-independent pathways of regulation of thymocyte function by interleukin 6.

Recombinant human interleukin 6 (IL-6), also termed B-cell-stimulatory factor 2 (BSF-2) or interferon-beta 2, was found to stimulate the proliferation of mouse thymocytes costimulated with phytohemagglutinin (PHA). In addition, IL-6 synergistically enhanced the stimulation of thymocyte proliferation by recombinant human interleukin 1 (IL-1) or interleukin 2 (IL-2). Mature thymocytes lacking peanut agglutinin receptor are the main target of IL-6 action. Incubation of thymocytes with IL-6 in the presence of PHA resulted in an increased expression of the IL-2 receptor (IL-2R) as demonstrated by flow cytometry. Monoclonal antibody specific for the p55 chain of the murine IL-2R significantly reduced IL-6-stimulated thymocyte proliferation in the presence of the optimal concentration of PHA. However, the same monoclonal antibody failed to reduce IL-6-driven thymocyte proliferation in the presence of a suboptimal PHA concentration, suggesting that IL-6 stimulates thymocyte proliferation by way of IL-2-dependent and IL-2-independent pathways. These results indicate that, in addition to its earlier demonstrated ability to promote B-cell differentiation and growth, IL-6 also acts as a growth regulator in cells of the T-lymphocyte lineage. IL-6 is emerging as an important regulatory cytokine with multiple actions on immune functions.

Animals↗
PubMed1988

Immunosuppressive effect of the anti-IL-2-receptor monoclonal antibody, AMT-13, on organ-cultured fetal pancreas allograft survival.

Recently, prolongation of cardiac allograft survival in mice was reported using a rat anti-IL-2R mAb (AMT-13). However, its immunosuppressive action in vivo, alone and in combination with other immunosuppressants, and its effect on other organ transplants has not been extensively studied. We grafted cultured fetal pancreas from CBA (H-2k) donors to Balb/c (H-2d) mice. Recipients were treated with 10 consecutive daily injections each of 20 micrograms AMT-13 only, or with an additional mild immunosuppression of 350 rads irradiation. Control groups received rat immunoglobulin or 350 rads irradiation. Graft survival and the phenotype of infiltrating cells were assessed histologically and immunocytochemically on days 12, 17, and 21, and soluble IL-2R levels were measured in the serum with a quantitative ELISA in all recipients. Two of five grafts in the AMT-13-treated group had islets on day 12 posttransplantation despite lymphocytic infiltration in all grafts, while at this time all grafts of rat Ig treated control mice were completely rejected with only scar tissue and a few lymphocytes remaining. Additional immunosuppression with 350 rads irradiation had a marked additive effect with AMT-13. Soluble IL-2R levels in the serum of untreated recipients were not elevated compared with normal serum levels, but recipients injected with AMT-13 had multifold increased soluble IL-2R levels. The percentage of IL-2R+ cells in the grafts of AMT-13-treated animals was either normal (less than 5%) or increased (20%) in the additionally irradiated mice, providing strong evidence that the immunosuppressive effect of AMT-13 is not due to a depletion of activated IL-2R+ lymphocytes.

Animals↗
PubMed1988

Interleukin 2 receptor-targeted therapy--rationale and applications in organ transplantation.

Despite major advances in immunopharmacology for use in clinical organ transplantation, graft rejection and drug-induced side effects remain the major problems with currently available immunosuppressive modalities. Recent advances in hybridoma technology have produced relatively effective and reproducible biological immunosuppression with monoclonal antibodies; indeed, OKT3 and anti-T12 mAbs have been employed with considerable success as adjuncts to chemical suppression in treating rejection. Nonetheless, the use of such antibodies broadly reactive to differentiation antigens on T lymphocytes does not solve the problems of side effects caused by general immunosuppression. An ideal therapeutic agent should target only lymphocytes that participate in rejection of foreign tissue without affecting physiological host immune surveillance and normal defense mechanisms. Theoretically, this goal could be achieved by "antigenic suicide," or by using the appropriate antiidiotypic antibodies or mAbs against the antigen combining site of T cell receptors. However, because of the intense polymorphism of transplantation antigens and the vast genetic repertoire encoding for the T cell antigen receptor, success of such forms of specific immunosuppression, at least at this time, is highly improbable.

Animals↗
PubMed1988

Regulation of in vivo immunological reactions by monoclonal antibody against lymphocyte activation antigen.

In vivo effects of a monoclonal antibody that recognizes rat lymphocyte activation antigen were studied. Spleen cells obtained from sheep red blood cell (SRBC)-immunized rats developed strong PFC response against SRBC. However, the 5C6-F4 treatment resulted in the inhibition of subsequent development of PFC response. The suppression of PFC response was due to the inhibition of generation of helper T cells, but not due to the preferential induction of suppressor cells. In addition, 5C6-F4 antibody was also found to inhibit the clinical expression of collagen-induced rat arthritis and the synovial inflammation in collagen-induced arthritis rats. Furthermore, the in vivo generation of cytotoxic cells against syngeneic tumor cells was also inhibited by 5C6-F4 antibody. The in vivo administration of 5C6-F4 antibody did not cause any pathological changes in brain, lung, liver, kidney, spleen, thymus, and lymph nodes.

Animals↗
PubMed1988

Interleukin 2 receptor in patients with localized and systemic parasitic diseases.

An enzyme-linked immunosorbent assay was used to quantify soluble interleukin 2 receptor (IL-2R) in the serum of patients with helminthic and protozoal infections. The results demonstrated that levels of IL-2R were normal in patients with helminthic infections limited to the intestinal tract (ascariasis, trichuriasis), but significantly elevated in patients with systemic or long-lasting infections (strongyloidiasis, schistosomiasis, fascioliasis, opisthorchiasis). In patients infected with Schistosoma mansoni levels of IL-2R were higher in those with the hepatosplenic than in those with the intestinal form of the disease. Patients with malaria also showed increased serum levels of IL-2R, irrespective whether the infection was caused by Plasmodium falciparum or P. vivax. No difference was observed between patients with acute or history of malaria. The highest levels of IL-2R were observed in patients with visceral leishmaniasis. Interestingly, in these patients the concentration of IL-2R correlated to specific antibody titre. The results are discussed in the context of preferential activation of T lymphocytes, B lymphocytes and/or macrophages during the course of the different parasitic infections investigated.

Enzyme-Linked Immunosorbent Assay↗
PubMed1988

Monitoring of interleukin-2 receptor (IL-2R) expression in vivo and studies on an IL-2R-directed immunosuppressive therapy of active and adoptive adjuvant-induced arthritis in rats.

Recent evidence indicates that adjuvant arthritis (AA) of rats induced by complete Freund's adjuvant (CFA) is an autoimmune disease that is mediated by T cells. This report describes the distribution of activated IL-2 receptor (IL-2R)-bearing cells in spleen, popliteal lymph nodes (PLN) and blood in AA rats and in naive healthy rats using the monoclonal antibody (mAb) ART-18. It was found that in the primary lymph nodes (injected side) two peaks of elevated numbers of IL-2R-positive cells (Day 9/10 with a 40-fold increase; Day 25 with a 75-80-fold increase) occur. The PLN of the non-injected site also show an increase (30-fold) in the number of IL-2R-positive cells on Day 25. This investigation also included the monitoring of soluble IL-2R in the serum of AA rats in comparison to control sera of non-induced rats. The incidence of free IL-2R in the serum of AA rats does not completely correlate with the pattern of the distribution of receptor-bearing cells in PLN; elevated levels of IL-2R were observed at Day 9 and subsequently declined to below control levels. On Day 25, there was no correlation between IL-2R+ cells and soluble IL-2R. ART-18 was not active in suppressing the development of AA, in contrast to the complete inhibition of the passively transferred AA.

Animals↗
PubMed1987

Elevated titers of cell-free interleukin 2 receptor in serum of lupus mice.

Activation/proliferation of mouse and human T and B cells is associated with expression and subsequent release of interleukin 2 receptors (IL 2R) into the milieu. The soluble form of IL 2R, at least in part, retains its ability to bind to IL 2 and to anti-receptor antibodies, but its exact structure remains unknown. Because systemic lupus erythematosus (SLE) is associated with T and B cell activation, we have used monoclonal anti-IL 2R antibodies in an ELISA to measure levels of IL 2R in sera of various lupus strains. High levels of the released receptor were found at an active clinical stage in sera of four autoimmune strains of mice homozygous for the lpr (lymphoproliferation) gene that causes T cell expansion, massive lymphoid organ enlargement, and promotes the autoimmune process. High levels were also found in lupus mice characterized primarily by B cell proliferation (BXSB males) and in (NZB X W)F1 mice characterized by T and B cell activation. Similarly high IL 2R serum levels could be induced experimentally in normal mice injected with immunostimulants such as bacterial lipopolysaccharide or Freund's complete adjuvant. The results indicate that IL 2R serum levels may provide a good marker of ongoing lymphoid cell activation/proliferation, and thus might be useful in the follow-up of patients with systemic autoimmune or other lymphoproliferative disorders. The biologic roles, if any, of the soluble form of IL 2R and its effects in normal and abnormal conditions remain to be determined.

Animals↗