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T Diamantstein

Publications and source records attributed to T Diamantstein.

At least 127 records · Page 7Linked to original sources
PubMed1987

An ELISA that detects cell-associated and released rat IL-2 receptors in a soluble form.

A mouse anti-rat interleukin-2 receptor (IL-2R) monoclonal antibody (mAb), ART-65, has recently been developed which recognizes the rat IL-2R but binds to an epitope distinct from that recognized by the mAb ART-18. The availability of two mAb against the rat IL-2R molecule permitted the development of an enzyme-linked immunosorbent assay (ELISA) which detects soluble and solubilized rat IL-2R. Using this ELISA, time course studies of ConA and LPS-activated rat splenocytes revealed that IL-2R are released into their environment during the culture period, and that IL-2R can be detected in rat sera. The significance of the results is discussed.

Animals↗
PubMed1987

Signals for activation and proliferation of murine T lymphocyte clones.

Biochemical signals required for the growth of T cell clones were studied. Antigen-specific helper T cell clones, 6-1 and KO.6, could enter the state similar to the resting state where the cells expressed only small numbers of interleukin 2 (IL2) receptors and could not respond to IL2 without antigenic stimulation. A combination of a phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), and a calcium ionophore, A23187, induced the expression of IL2 receptors on resting 6-1 cells and induced DNA synthesis in the presence of IL2. TPA alone did not induce IL2 receptors. A23187 induced the expression of the receptors to some extent but did not induce DNA synthesis even in the presence of IL2. IL2 receptors induced by A23187 alone were mostly low affinity receptors, whereas the combination of TPA and A23187 induced high affinity receptors in addition to low affinity receptors. Resting KO.6 cells produced IL2 in response to a combination of TPA and A23187, whereas either one of the agents did not induce the production of IL2. Dicaprylin, a permeable diacylglycerol and a potent activator of protein kinase C (the Ca2+/phospholipid-dependent enzyme) could replace TPA in both cases when dicaprylin was repeatedly added to the culture. These results suggest that strong and continuous activation of protein kinase C together with calcium mobilization is required for IL2 production and IL2 receptor expression. On the contrary, signals for DNA synthesis generated by binding of IL2 to IL2 receptors are different from those for IL2 production and IL2 receptor expression, as the combination of TPA and A23187 could not induce DNA synthesis without IL2.

Animals↗
PubMed1987

Identification of IL 2R+ T cells and macrophages within rejecting rat cardiac allografts, and comparison of the effects of treatment with anti-IL 2R monoclonal antibody or cyclosporin.

Monoclonal antibodies to lymphokine-induced activation antigens of lymphocytes and macrophages were used to analyze the intragraft events occurring during acute rejection of rat heterotopic cardiac allografts. The cells present during untreated rejection were then compared with those present in situ after immunosuppression with the mouse anti-rat IL 2 receptor (anti-IL 2R) monoclonal antibody ART-18 or cyclosporin (CsA). Untreated rats rejected their grafts within 7 days, whereas rats receiving 10 days of i.v. ART-18 antibody therapy showed graft prolongation to more than 21 days, and rats receiving CsA for 7 days maintained their grafts indefinitely. Untreated rejection was associated with an influx of T (W3/13+) cells and macrophages (ED-1+, ED-2+). Activated mononuclear cells (IL 2R+) were identified within rejecting grafts from day 2, and their numbers peaked on days 4 to 6 when 15 to 20% of infiltrating leukocytes were IL 2R+. Double labeling studies of IL 2R+ cells present at day 6 showed surprisingly that both T cells and macrophages expressed IL 2R. In particular, although 55.8 +/- 6.9% (mean +/- SD) of IL 2R+ cells expressed the pan-T cell antigen 3/13, a similar proportion of IL 2R+ cells (49.8 +/- 8.2%) expressed the macrophage antigen ED-2. Conversely, both T cells and macrophage populations showed heterogeneity in their expression of IL 2R, because 39.2 +/- 12.2% of T cells and 31.0 +/- 13.4% of macrophages were IL 2R+. In addition, inflammatory macrophages at day 6 expressed the A1-3 antigen. Expression of this antigen by macrophages has previously been linked with development of macrophage procoagulant activity, and in this model intragraft inflammatory macrophages were closely associated with widespread deposits of fibrin. By comparison with untreated animals, rats treated with either ART-18 or CsA both lacked detectable IL 2R+ cells during the first 14 days post-transplantation (post-Tx), and showed significantly less cellular infiltration. However, although grafts of CsA-treated animals continued to remain IL 2R- and failed to stain with the macrophage activation marker A1-3, ART-18-treated rats showed increasing infiltration by both IL 2R+ mononuclear cells and A1-3+ macrophages, as well as increasing perivascular and interstitial fibrin deposition, prior to rejection by day 22. These studies document the presence of small number of activated intragraft T cells and macrophages during rat cardiac rejection, and show how CsA, and to a lesser extent anti-IL 2R therapy, inhibit this in situ activation and prolong graft survival. (ABSTRACT TRUNCATED AT 400 WORDS)

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PubMed1987

Soluble interleukin 2 receptors are released by long term-cultured insulin-specific T cells transiently after contact with antigen.

An enzyme-linked immunosorbent assay was used to quantitate soluble interleukin 2 receptors (IL 2R) released by antigen-dependent, insulin-specific murine T cells into the culture supernatant, as well as cell-associated IL 2R present in cell lysates. IL 2R were released solely after T cell activation by antigen. The release of IL 2R was transient, reaching optimal levels within 72 hr after antigen challenge and gradually declining to background levels thereafter, when the cells were subcultured in IL 2-enriched medium. The decrease in the amount of IL 2R released during culture in IL 2-containing medium paralleled the decrement in cellular IL 2R detected in cell lysates, in cell surface-expressed IL 2R as determined by cytofluorometry, as well as in high-affinity IL 2R. In contrast, IL 2R were constitutively released by an IL 2-dependent T cell clone. Soluble IL 2R might exert an immunoregulatory function by competing with cellular IL 2R for IL 2 binding.

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PubMed1987

Selective immunosuppression with anti-interleukin 2 receptor-targeted therapy: helper and suppressor cell activity in rat recipients of cardiac allografts.

(LEW X BN)F1 cardiac allografts are rejected within 8 days in unmodified LEW rats. ART18, a mouse anti-rat IgG1 monoclonal antibody which binds specifically in vitro to the interleukin 2 receptor (IL 2R) molecule expressed primarily on activated T cells, prolongs allograft survival in a dose-dependent fashion to ca. 3 weeks (p less than 0.001) after being administered for 10 days after transplantation. This effect was related to the specificity of the antibody for IL 2R, as therapy with ART62 (a monoclonal antibody recognizing MHC class I antigen but not binding the rat IL 2R) was ineffectual. Suppressor activity was detected in spleen cells of ART18-treated grafted hosts: in vivo, splenic T suppressor/cytotoxic fraction adoptively transferred into normal LEW improved donor-specific but not third-party test graft survival (17 days, vs. 8 days, respectively, p less than 0.001); in vitro, mixed lymphocyte reaction was profoundly but nonspecifically inhibited (less than 5% of test mixed lymphocyte reaction, p less than 0.001 as compared to acutely rejecting controls). In contrast, splenic T helper (Th) cells from ART18-treated hosts were functionally depressed, as noted by their passive transfer into immunologically anergic B recipients of cardiac allografts (rejection in ca. 40 days, vs. ca. 13 days after transfer of Th from specifically sensitized rats). ART18 treatment also resulted in diminished elaboration of IL 2 as compared to normal (p less than 0.005) or acutely rejecting hosts (p less than 0.001); however, a remarkable increase in the production of IL 3 occurred (p less than 0.001). These results demonstrate that IL 2R-targeted therapy of immunocompetent graft recipients produces a selective immune defect in which donor-specific T suppressor cells are spared, but Th cells attenuated or destroyed. Decreased elaboration of IL2 concomitantly augments the release of IL 3, a lymphokine which might play a role in suppressor effect in vivo. In addition, IL 2R-targeted therapy of the immunodeficient graft recipients abrogates the capacity of alloactivated T cells to re-establish acute immune responsiveness.

Animals↗
PubMed1987

Blocking of interleukin 2 (IL 2) binding to the IL 2 receptor is not required for the in vivo action of anti-IL 2 receptor monoclonal antibody (mAb). I. The production, characterization and in vivo properties of a new mouse anti-rat IL 2 receptor mAb that reacts with an epitope different to the one that binds to IL 2 and the mAb ART-18.

A mouse anti-rat interleukin 2 (IL 2) receptor (IL 2R) monoclonal antibody (mAb), ART-65, has been developed. As shown by fluorescence-activated cell sorter analysis and immunoprecipitation studies, ART-65 recognizes in a species-specific manner the same molecule as does ART-18, a mAb which has been shown previously to recognize the rat receptor for IL 2. ART-65 and ART-18 do not competitively inhibit the binding of each other to activated T cells. ART-65, in contrast to ART-18, does not inhibit the binding of IL 2 to cells nor does it have any inhibitory effect in vitro on IL 2-driven proliferation of rat T lymphoblasts. Therefore, ART-65 is another mAb recognizing the rat IL 2 receptor, but binding to an epitope distinct from that recognized by either IL 2 or ART-18. We compared the in vivo activity of the mAb ART-65 and ART-18 with that of the W3/25 mAb in a local graft-vs-host reaction (GVHR). Similar to the anti-W3/25 treatment, ART-65 and ART-18 inhibited GVHR. The results demonstrate that GVHR depends on a small subpopulation of IL 2R+ cells present in the W3/25+ T cell population because IL 2R-targeted therapy was as effective as the treatment with W3/25 mAb which reacts with the entire T helper cell population. Moreover, the results argue against the possibility that anti-IL 2R mAb act via blockade of the IL 2 binding to IL 2R+ cells and/or by inhibiting the IL 2-driven expansion of the antigen-activated clones. The results support the view that IL 2R-targeted therapy results in the elimination of the IL 2R+ cells.

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PubMed1987

Monoclonal antibodies identify three epitope clusters on the mouse p55 subunit of the interleukin 2 receptor: relationship to the interleukin 2-binding site.

A new rat monoclonal antibody (5A2) directed against the mouse interleukin 2 receptor (IL2R) is described. This antibody binds specifically to IL2R+ cells, competes with both cold IL2 and 125I-labeled IL2 for the IL2-binding site and inhibits IL2-induced T cell proliferation. This reagent was compared to five previously characterized rat monoclonal antibodies directed against the p55 subunit of the mouse IL2R. The capacity of all the antibodies to inhibit IL2-induced T cell proliferation was assessed. The relationship of these eight antibodies to each other and to the IL2-binding site was studied by cross-inhibition assays, and by Scatchard analysis of the data. The results indicate that the six monoclonal antibodies recognize epitopes in three areas of the p55 subunit of the mouse IL2R. Antibodies against two of the clusters affect IL2 binding. One cluster defined by 3 antibodies is probably located in the area of the IL2-binding site as there is competitive inhibition between IL2 and antibodies against this cluster. A single antibody directed against an epitope outside this cluster appears to inhibit IL2 binding by inducing a conformational change in the p55 subunit of the IL 2R. Two other antibodies identify a third region which is not involved in the formation of the binding site.

Animals↗
PubMed1987

Curing BB rats of freshly manifested diabetes by short-term treatment with a combination of a monoclonal anti-interleukin 2 receptor antibody and a subtherapeutic dose of cyclosporin A.

The BioBreeding (BB) rat develops spontaneously a syndrome resembling human type I diabetes mellitus. The short-term treatment of newly diagnosed diabetic BB rats with the anti-interleukin 2 receptor (IL 2R) monoclonal antibody ART-18 in combination with a subtherapeutic dose of cyclosporin A for 10 days, a treatment shown previously to eliminate specifically antigen-activated IL2R+ T lymphocytes by sparing suppressor cells, resulted in normoglycemia in 70% of the animals, the maintenance of B cell volume density and an increase in pancreatic insulin content. Moreover, the glucose tolerance of successfully treated animals was not significantly different from that of normoglycemic BB rats during the whole observation period (up to 120 days after the end of the therapy). This is the first report on successful treatment of a spontaneous autoimmune disease by a short-term and specific immunosuppressive regimen with limited side effects.

Animals↗
PubMed1987

Four epitopes on the rat 55-kDa subunit of the interleukin 2 receptor as defined by newly developed mouse anti-rat interleukin 2 receptor monoclonal antibodies.

Four new mouse monoclonal antibodies (mAb), ART-38, ART-35, ART-75 and ART-94, directed against the rat interleukin 2 receptor (IL 2R) have been developed. As shown by immunoprecipitation studies they all recognize specifically the 55-kDa subunit of the rat IL 2R. These mAb were compared to three previously characterized mouse mAb directed against the 55-kDa molecule of the rat IL 2R, namely the ART-18, ART-65 and OX-39 mAb. Out of all seven mAb, only ART-18 and OX-39 were found to inhibit the IL 2 binding to activated T cells, while IL 2R inhibited the binding of ART-18 alone. ART-18 was the only mAb found to inhibit the IL 2-dependent proliferation of cells carrying the IL 2R. Scatchard plot analyses showed gross differences in the numbers of mAb-binding sites ranging between 30,000 (ART-65) and 165,000 (ART-75) as well as in their affinities which ranged between 2.5 X 10(-9) M (ART-38) and 8.3 X 10(-10) M (OX-39). Cross inhibition studies revealed that the mAb recognize four different epitopes on the 55-kDa rat IL 2R subunit.

Animals↗
PubMed1987

Retroviral expression of the human IL-2 gene in a murine T cell line results in cell growth autonomy and tumorigenicity.

In mature T lymphocytes (T cells) the regulated expression of the genes for interleukin-2 (IL-2) and its receptor (IL-2R) constitutes an essential part in controlling the cell growth. Evidence has been provided which suggests the involvement of an aberrant function of the IL-2 system in developing T cell neoplasms, particularly the adult T cell leukemia/lymphoma (ATL). As an approach to examine the extent of the IL-2 system contribution to T cell neoplasms, we created the experimental conditions wherein both IL-2 and IL-2R are expressed constitutively in a murine T cell line. We made use of a retroviral vector to infect an IL-2-dependent CTLL-2 line and lead to the expression of human IL-2. Here, we show that the virus-infected cells not only proliferate in vitro in the absence of exogenously supplied IL-2 under certain conditions, but also develop tumors (lymphomas) in nude and syngeneic mice.

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PubMed1987

Prolongation of rat pancreatic islet allograft survival by treatment of recipient rats with monoclonal anti-interleukin-2 receptor antibody and cyclosporin.

Since interleukin-2-receptor expressing cells play a role in allograft rejection, we investigated the effect of anti-interleukin-2 receptor monoclonal antibody treatment on graft survival of allografted pancreatic islets. When pancreatic islets obtained from Lewis A-rats (haplotype RT1a) were grafted under the kidney capsules of streptozotocin-diabetic Lewis rats (haplotype RT1u), the recipients relapsed into hyperglycaemia within 11 days (7 +/- 1 days). Treatment of the recipient rats with low-dose cyclosporin (1.5 mg/kg body weight) had no effect on allograft survival (9 +/- 1 days). The application of anti-interleukin-2 receptor monoclonal antibody (1 mg/kg body weight) for 10 days resulted in a prolongation of allograft survival (42.5 +/- 15.3, p less than 0.01). In 3 out of 11 animals a permanent normoglycaemia (greater than 120 days) associated with glucose intolerance was observed. When the recipients were treated for 10 days with cyclosporin and anti-interleukin-2 receptor monoclonal antibody, the allograft survival was also prolonged (45.1 +/- 14.6, p less than 0.01); again 3 out of 11 animals remained permanently normoglycaemic while exhibiting a normal glucose tolerance.

Animals↗
PubMed1987

Differential requirement for accessory cells in polyclonal T-cell activation.

Highly purified rat Ia-negative (OX-6-) and Ia-positive (OX-6+) T cells were employed to examine the requirement for accessory cells (AC) and/or soluble factors in the activation of resting T cells with Con A, PHA, sodium periodate, or antigen. A variety of cells were employed as AC, including Ia-positive and Ia-negative macrophages (M phi), gamma-irradiated (2000 rad) or non-irradiated OX-6+ T cells, and several Ia-negative adenovirus-transformed rat embryo fibroblast cell lines. Our results suggested that for the expression of IL-2 receptors (IL-2R) and proliferation of OX-6- T cells in response to Con A, PHA, or antigen, there was an obligatory requirement for the presence of AC which could not be overcome by the addition of IL-1 and/or IL-2. Activation of OX-6- T cells with antigen required the presence of Ia+ AC, while activation with mitogens could be initiated with Ia- AC. M phi were efficient in AC function in all responses tested, while the AC function of OX-6+ T cells (TAPC) proved discriminatory under different conditions. The optimal response to PHA required much higher concentrations of TAPC as AC than for the Con A response. TAPC failed to stimulate sodium periodate-treated T cells under any conditions tested. Furthermore, when TAPC were employed as AC, their antigen-presenting ability was radiosensitive, while their AC function for Con A and PHA was radioresistant. These results suggest that molecules involved in T cell-AC interactions may differ, depending on the source of AC and/or type of the proliferative stimulus provided to T cells. This data has been discussed in the context of T-cell activation.

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PubMed1987

B cells as antigen-presenting cells: antigen-specific IL-2 production by cloned T cells without expression of IL-2 receptors.

A murine T cell clone, 24-2C, responds specifically to human IgG (HGG) in the context of I-Ab. B cells purified from mouse spleen cells were examined for their function as antigen-presenting cells (APC) in the response of 24-2C cells to HGG. B cells functioned as APC for IL-2 production but not for proliferation, whereas spleen cells or spleen-adherent cells functioned as APC for both IL-2 production and proliferation. LPS-activated B cells also failed to induce the proliferative response. The addition of the culture supernatant of 24-2C cells stimulated with HGG presented by irradiated spleen cells to the culture of 24-2C cells, irradiated B cells, and HGG induced the proliferative response of 24-2C cells, whereas IL-1, IL-3, and/or interferon-gamma did not reconstitute the proliferation. The expression of IL-2 receptors (IL-2R) on 24-2C cells was examined using a monoclonal anti-mouse IL-2R antibody AMT 13 or 7D4. 24-2C cells cultured with spleen cells as APC expressed IL-2R. Those cultured alone or with B cells as APC did not express IL-2R. Enlargement of 24-2C cells in response to HGG was also examined, and the relative cell size of those cultured with B cells or spleen cells as APC was larger than that of those cultured alone. These results demonstrate that B cells as APC induce IL-2 production and cell size enlargement in the response of 24-2C cloned T cells to HGG, but not IL-2R expression nor proliferation.

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PubMed1987

The ontogeny of the interleukin 2 receptor expression and of the interleukin 2 responsiveness in the rat thymus.

The ontogeny of the interleukin 2 receptor (IL 2 R) expression and of the IL 2 responsiveness has been investigated in the rat thymus. In tissue sections, IL 2 R-bearing cells were first detected at day 16 of gestation using the anti-IL 2 R mAb ART-18. In contrast to mice, IL 2 R-bearing cells of the rat are localized mainly in the thymic medulla from the first day of the corticomedullary compartimentalization, and not in the cortex. They are found in regions with a high expression of MHC class II antigens. The proportion of IL 2 R-bearing cells increases during gestation, reaches a peak at the first day after birth and declines to the adult level in the following weeks. The appearance of medullary localized IL 2 R-bearing cells is paralleled with the capacity of the thymocytes to proliferate in response to IL 2 without any additional stimuli.

Animals↗
PubMed1987

The mouse high affinity IL 2 receptor complex. I. Evidence for a third molecule, the putative gamma-chain, associated with the alpha- and/or beta-chain of the receptor.

Low and high affinity receptors for interleukin 2 were investigated on mitogen-activated mouse T lymphocytes and on interleukin 2 (IL2) receptor-bearing T cell lines by chemical crosslinking of 125I-labelled interleukin 2 (125I IL2) to its binding proteins or membrane proteins associated with the IL2 binding sites. In all cells investigated, the crosslinking produced a 65-70 kD complex thought to be one beta-chain molecule (55 kD IL2 receptor) and one IL2. Occasionally, a 120-130 kD band could be seen which is thought to be IL2 bound to beta-chain homodimer. Using low IL2 concentrations (200 pM), high affinity receptor-bearing cells showed specific additional complexes. Either bands of 85 kD, 105 kD and greater than 160 kD or of 90 kD and 115 kD and greater than 160 kD could be found when mouse T blasts or CTLL 16 cells were used, respectively. In the exclusively low affinity receptor-bearing T cell line Eb, only a single band of 70 kD (beta-chain + IL2) was detectable. These results show that in addition to a 85-90 kD complex, as shown already in humans, a third complex of 105-115 kD exists in mice that is specifically associated with high affinity receptors. This is the first indication of a putative gamma-chain of the high affinity IL2 receptor. All IL2-containing complexes of the mouse cells could be precipitated by the newly developed MAb AMT 45-20 raised against the beta-chain of the mouse IL2R and recognizing an epitope distinct from those recognized by the MAb AMT 13 or IL2. This suggests that either 1) all complexes contain the beta-chain, 2) share an antigenic determinant with the beta-chain, or 3) that the higher mw complexes become coprecipitated with the beta-chain.

Animals↗
PubMed1987

Determination of cell-free interleukin 2 receptor level in the serum of normal animals and of animals bearing IL-2 receptor positive tumours with high or low metastatic capacity.

Serum levels of cell-free interleukin-2 receptors were elevated above normal in mice bearing the IL-2R positive T-cell lymphoma Eb or its highly metastatic variant ESb. Although ESb cells expressed less IL-2R molecules than Eb cells on their cell surface, serum receptor levels were raised more quickly in ESb than in Eb tumour bearing animals. Elevated IL-2R serum levels were a sensitive tumour marker in animals bearing the aggressive variant ESb but not in animals bearing the low metastatic line Eb. Peritoneal ascites tumour-bearing animals had higher serum IL-2R levels than corresponding animals with subcutaneously growing tumours. Thus, serum IL-2R levels in tumour-bearing animals were dependent on the tumour line and influenced by the site and mode of tumour growth.

Animals↗
PubMed1987

Cyclosporine and dexamethasone inhibit T-lymphocyte MHC class II antigens and IL-2 receptor expression in experimental autoimmune uveitis.

Results of recent studies indicated that a monoclonal ART18 antibody recognizes the receptor sites or closely related structures for IL-2 on activated rat T-cells. The major histocompatibility complex (MHC) class II (Ia) antigens (RT1B and RT1D in rat), detected with OX6 antibody, and OX17 antibody, may be present on activated rat T-cells. In the present report, we examined the effect of corticosteroids and cyclosporine (CsA) on the expression of IL-2 receptors and Ia antigens by the T-cells, which constituted the major cellular component of the ocular infiltration during the period of peak ocular inflammatory activity in experimental autoimmune uveoretinitis (EAU). Lewis rats immunized with retinal S-antigen (S-Ag) and treated for a limited time with suboptimal doses of either CsA or Dexamethasone (Dex) subsequently developed EAU. The inflamed ocular tissues were studied using an immunoperoxidase staining technique. CsA treatment resulted not only in the inhibition of IL-2 receptors on T-cells, but also in the prevention of the induction of Ia antigen expression on T-cells and other non-lymphoid cells. Dex treatment resulted in less inhibition of the expression of both class II antigens and IL-2 receptor by the infiltrating T-cells.

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