Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P14784 (IL-2 receptor)
 3,849 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An important unanswered question in clinical immunology is why the histocompatibility antigens HLA-B8/DR3 should be associated with at least nine quite different immune-mediated diseases. The purpose of this study was to examine the mechanism of an immunologic abnormality, commonly found in healthy individuals with HLA-DR3, that may reflect an immune defect predisposing to autoimmunity. Fourteen healthy subjects with HLA-DR3 had a proliferative response to a suboptimal concentration of PHA nearly eight-fold lower than that observed in 10 individuals without this HLA antigen. Impaired responsiveness to PHA was more strongly associated with HLA-DR3 than with HLA-B8. The IL-2 concentration in mitogen-stimulated cultures was similarly decreased in subjects with HLA-DR3 and was highly predictive of the proliferative response 24 h later (r = 0.82, P less than 0.0001). Inhibition of IL-2 utilization by anti-IL-2 receptor antibody indicated that the reduced IL-2 concentration reflects impaired lymphokine production rather than increased utilization. Expression of IL-2 receptors is decreased in these subjects, although the magnitude of their proliferative response is appropriate for the available lymphokine. These results indicate that impaired lymphocyte activation associated with HLA-DR3 reflects impaired IL-2 production and an abnormality of activation events preceding the production of this lymphokine.
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PMID:Mechanism of a lymphocyte abnormality associated with HLA-B8/DR3 in clinically healthy individuals. 278 12

Myasthenia Gravis (MG) is an autoimmune disorder of neuromuscular transmission associated with antibodies (Ab) against acetylcholine receptor (AChR). Autoantibody production is a T-cell-dependent phenomenon perhaps caused by aberrant immunoregulation. So far, a possible role for immunoregulatory molecules has not been investigated in the pathogenesis of MG. Since interleukin-2 (IL-2) is able to induce peripheral blood mononuclear cell (PBMC) proliferation without a previous activating signal and to upregulate IL-2-receptor expression, we have evaluated the activation state of PBMC in patients with MG, by cytofluorographic analysis of CD25 expression and by testing their sensitivity to recombinant IL-2 (rIL-2) without any known previous stimulation. We found no significant difference in CD25 expression in a large group of patients compared to controls. However, proliferative responses to rIL-2 were significantly higher in MG patients than in controls. In MG, as in controls, this response was time- and dose-dependent, was inhibited by an anti-IL-2 receptor Ab and correlated with an increased percentage of CD25+ T cells after rIL-2 exposure. The response was greater in patients with a high anti-AChR Ab titer and a severe form of the disease, and in patients tested before thymectomy. Thus blood T cells in MG showed functional signs of preactivation (high sensitivity to rIL-2 alone) without detectable CD25 expression on fresh cells, raising the possibility of aberrant IL-2 receptor regulation and/or expression in MG T cells. Decreased sensitivity to rIL-2 after thymectomy, associated with general clinical improvement, suggests a role for activated cells originating from the thymus in the pathogenesis of MG, and is of clinical relevance in patient follow-up. Our findings also provide a new approach in the study of MG pathogenesis: the search for aberrant immunoregulation mechanisms linked to defects in lymphokine circuits.
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PMID:High recombinant interleukin-2 sensitivity of peripheral blood lymphocytes from patients with myasthenia gravis: correlations with clinical parameters. 278 27

Studies of the diminished mitogen-induced proliferative response of T lymphocytes from older subjects show that aging must result in some defect(s) in the intracellular events required for transition from the G0 or quiescent state through the prereplicative interval and into the first S phase of the cell cycle. This conclusion is supported by observations of diminished inducibility of the lymphokine IL-2 and its receptor during aging. The current study demonstrates that decreased proliferative response to phytohemagglutinin (PHA) is also paralleled by decreased induction during the prereplicative interval of two of the most strongly enhanced proteins in mitogen-activated T cells: HSP90 and P73, which are also members of the heat-shock protein family. Diminished induction of HSP90 and P73 is observed in lymphocytes from older subjects (mean age 75), regardless of differences in health status of the subject populations. These results suggest that in vivo aging of human T cells results in a general defect in the induction of gene products required for transition from quiescence into the S phase of the cell cycle and that diminished T cell proliferation in advanced age is not due to a specific, "intrinsically immunologic" defect in induction of IL-2 and the IL-2 receptor.
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PMID:Diminished heat-shock protein synthesis following mitogen stimulation of lymphocytes from aged donors. 278 78

An immunosuppressive factor was obtained from culture supernatants of early human decidual cells. The suppressor factor was concentrated by gel filtration in a fraction with a molecular weight between 43,000 and 67,000 daltons. It was further purified by biochemical methods. Four peaks were obtained in the fraction with molecular weight between 43,000 and 67,000 daltons by anion exchange chromatography. Only the second peak had immunosuppressive activity in MLR. Lentil-lectin affinity chromatography of this suppressor factor showed that the suppressor factor had no affinity for lentil-lectin sepharose. Isoelectric focusing of the suppressor factor demonstrated four bands. The protein isoelectric (PI) point was approximately 7.50 in one band and between 6.85 and 7.35 in the other three bands. These results demonstrate that the suppressor factor is not glycoprotein but protein, whose PI is between 6.85 and 7.50. The suppressive effect of this purified factor on lymphokine production and lymphocyte activation was investigated. The addition of the purified suppressor factor to a culture of PBL stimulated with PHA suppressed not only IL-2 production and gamma-INF production, but also BSF-2 production. IL-2 receptor expression and transferrin receptor expression of PBL stimulated with PHA were also suppressed by addition of the suppressor factor. These results demonstrate that this suppressor factor inhibits lymphokine production and lymphocyte activation.
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PMID:Immunochemical characterization of the suppressor factor from early human decidual cells. 279 18

Altered cellular immunity in patients with advanced head and neck cancer includes impairments in lymphokine production, blastogenesis, in vitro cytotoxicity, and T-cell levels. Recent evidence for the potential importance of in lymphokine interleukin 2 (IL-2) in patients with cancer prompted a study of the kinetics of IL-2 receptor expression on lymphocytes from patients with untreated advanced head and neck cancer and normal subjects and an evaluation of the in vitro effects of the T-cell immune-reconstituting peptide, thymosin alpha 1. Concanavalin A-stimulated IL-2 receptor expression was maximal after 72 hours and was higher in normal subjects than in patients. This was due to lower levels of helper/inducer (CD4) cells expressing IL-2 receptors in the patients compared with the normal subjects. Thymosin alpha 1 further decreased levels of IL-2 receptor-positive (both CD4 and CD8) cells at 48 and at 72 hours. At 96 hours, levels of IL-2 receptor-positive cells and proportions of cells in G2 and M phases of the cell cycle were similar among both groups of subjects. Simultaneous cell kinetic studies indicated that thymosin alpha 1 down regulation of IL-2 receptors was not due to an effect on proliferation and that differences in IL-2 receptor expression at 72 hours among normal subjects and the patients with cancer were more likely related to differences in cell proliferation kinetics.
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PMID:Interleukin 2 receptor expression in patients with head and neck squamous carcinoma. Effects of thymosin alpha 1 in vitro. 280 15

Activated killer cells, unrestricted by major histocompatibility (MHC) antigens circulate in the peripheral blood of patients who have undergone autologous and allogeneic bone marrow transplant (BMT) and may contribute to the reduced risk of leukemic relapse observed after these procedures. Interleukin-2 (IL-2) in vitro augments this cytotoxicity and used therapeutically might thereby promote the eradication of minimal residual disease. In order to assess whether these effects on cytotoxicity can be reproduced in vivo, we studied changes in number, phenotype, and MHC unrestricted cytotoxicity of peripheral blood mononuclear cells obtained from patients with hematologic malignancy receiving IL-2 infusions. Patients with acute myeloid leukemia and multiple myeloma were treated after cytotoxic chemotherapy or autologous BMT. IL-2 infusions produced an initial lymphopenia, followed by a progressive recovery in mononuclear cell numbers and a rebound lymphocytosis after the termination of treatment. This affected all lymphocyte subsets; in particular CD25 (IL-2 receptor) positive cell numbers rose sevenfold. Cells with the ability to kill a natural killer (NK)-resistant, lymphokine activated killer cell (LAK)-sensitive target appeared in the circulation during 16 of 19 infusions and mean LAK activity rose from 5.9% to 15.5% during infusion (E:T ratio, 50:1; P less than .001). During IL-2 infusion, cells present in the peripheral blood inhibited the growth of myeloid leukemia blasts in agar after overnight co-culture. Depletion experiments showed that LAK activity was mediated by cells of both CD3- CD16+ (NK derived) and CD3+ CD16- (T derived) subsets. LAK precursor activity in peripheral blood also significantly increased during IL-2 infusion. Increases in major histocompatibility complex (MHC) unrestricted cytotoxicity can be produced by IL-2 infusions in vivo and may result in improved relapse-free survival following chemotherapy or BMT.
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PMID:Effects of recombinant interleukin-2 administration on cytotoxic function following high-dose chemo-radiotherapy for hematological malignancy. 280 69

Addition of recombinant interleukin-2 (rIL-2) to normal adult murine thymocytes in vitro as the only exogenous stimulus leads to a dose-dependent mitogenic response characterized by two distinct dosage kinetic components. The high-affinity IL-2 thymocyte response is mounted by in vivo-activated (IL-2 receptor light chain positive) thymocytes, while the low-affinity IL-2 response, of larger amplitude, is carried out by resting thymocytes. Addition of IL-2 to thymocytes also triggers intense IL-3 secretory responses with both high and low IL-2 affinity components. Addition of high IL-2 dosages to thymocyte bulk cultures results in a dramatic increase in IL-2 responsiveness for both proliferation and IL-3 secretion on a per viable cell basis and with tightly coupled temporal kinetics. The low-affinity component of IL-2-proliferative and IL-3-secreting responses is carried out by resting mature CD4+ thymocytes, as assessed by negative selection with monoclonal antibodies (mAb) plus complement. The mechanism of resting thymocyte activation by high doses of IL-2 is partially characterized. Depletion of endogenous thymus-adherent cells abolished both proliferation and IL-3 secretion, and addition of splenic accessory cells or peritoneal macrophages to depleted thymocytes restored IL-2 responsiveness. Mature CD4+ thymocytes spontaneously form rosettes with adherent accessory cells, while CD8+ thymocytes do so with much less efficiency. Rosette formation of CD4+, but not of CD8+ thymocytes, can be blocked by anti-CD4 mAb GK1.5. At the same dosage as it prevents rosette formation, mAb GK1.5 also blocks the low-affinity thymocyte response to IL-2. The high-affinity IL-2 response is completely resistant to the action of cyclosporin A (CsA), but the low-affinity IL-2 response, although of much larger amplitude, can be almost completely suppressed by CsA. Together, these results demonstrate that resting CD4+ thymocytes can be induced to proliferation and lymphokine secretion by IL-2 alone in a process that is dependent on interaction with accessory cells, involves CD4 adhesion molecules and triggers activation through a CsA-sensitive pathway. In addition, the results demonstrate that IL-2 alone is able to enhance thymocyte IL-2 responsiveness and IL-3 secretory responses in vitro. The ability of IL-2 to induce and maintain thymocyte function is discussed in the light of these results.
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PMID:Triggering of thymocyte function by IL-2 as the only exogenous stimulus; analysis of two distinct modes of IL-2-induced thymocyte proliferation and IL-3 secretion in vitro. 280 75

The mouse cytotoxic T cell clone (CTLL-2) was able to grow in the presence of culture medium supplemented only with transferrin, 2-mercaptoethanol, and recombinant interleukin 2 (IL-2). This lymphokine stimulated the synthesis of DNA in these cells. Similarly, phorbol esters, which activate protein kinase C, induced DNA synthesis in this clone. Furthermore, this later proliferation was not blocked by anti-IL-2 receptor antibodies, which inhibited IL-2-induced proliferation, suggesting that it was not indirectly due to the secretion of IL-2 by the cells. CTLL-2 cells pretreated with high doses of phorbol esters for 48 h down regulated protein kinase C and were depleted of this enzyme. This was shown by: 1) purification and in vitro assay of protein kinase C; 2) the lack of effect of phorbol esters in the stimulation of the Na+/H+ anti-porter which has been directly linked to the activation of protein kinase C. As expected, those protein kinase C-depleted cells no longer synthesized DNA and proliferated in response to phorbol esters. However, they proliferated identically to control cells in response to IL-2. Therefore, our results suggest two different pathways for T cell proliferation, one which involves protein kinase C and the other which does not.
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PMID:The role of protein kinase C in T lymphocyte proliferation. Existence of protein kinase C-dependent and -independent pathways. 284 66

Interleukin-2 (IL-2) is a lymphokine synthesized by T cells following activation. Resting T cells do not express IL-2 receptors, but receptors are rapidly expressed on T cells following interaction of the antigen-specific T-cell receptor complex with appropriately processed and presented antigens. Anti-Tac, a monoclonal antibody that recognized the IL-2 receptor, has been used to purify the receptor. The recognized the IL-2 receptor, has been used to purify the receptor. The receptor is a 55-Kd glycoprotein comprised of 272 amino acids including a single 19-amino transmembrane domain and a short intracytoplasmic domain composed of 13 amino acids at the carboxy terminus. Normal resting T cells and most leukemic T-cell populations examined did not express IL-2 receptors; however, the leukemic cells of all patients with human T-cell lymphotrophic virus (HTLV-I)-associated adult T-cell leukemia (ATL) expressed the Tac antigen. In HTLV-I-infected cells, the 42-Kd long open reading frame (tat) protein encoded in part by the tat region of HTLV-I may act as a transacting activator that induces transcription of the IL-2 receptor gene, thus providing an explanation for the constant association of HTLV-I infection of lymphoid cells and IL-2 receptor expression. The constant display of large numbers of IL-2 receptors which may be aberrant in the ATL cells may play a role in the uncontrolled growth of these leukemic T cells. Patients with the Tac-positive ATL are being treated with both unmodified and toxin-conjugated forms of anti-Tac monoclonal antibody directed toward this growth factor receptor.
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PMID:The interleukin-2 receptor on normal and malignant lymphocytes. 288 69

Antigen-induced activation of resting T-cells induces the synthesis of interleukin-2 (IL-2), as well as the expression of specific cell surface receptors for this lymphokine. There are at least two forms of the cellular receptors for IL-2, one with a very high affinity and the other with a lower affinity. We have identified two IL-2 binding peptides, a 55-kd peptide reactive with the anti-Tac monoclonal antibody, and a novel 75-kd non-Tac IL-2 binding peptide. Cell lines bearing either the p55, Tac, or the p75 peptide alone manifested low-affinity IL-2 binding, whereas cell lines bearing both peptides manifested both high- and low-affinity receptors. Fusion of cell membranes from low-affinity IL-2 binding cells bearing the Tac peptide alone with membranes from a cell line bearing the p75 peptide alone generates hybrid membranes bearing high-affinity receptors. We propose a multichain model for the high-affinity IL-2 receptor in which both the Tac and the p75 IL-2 binding peptides are associated in a receptor complex. In contrast to resting T-cells, human T-cell lymphotropic virus I-associated adult T-cell leukemia cells constitutively express large numbers of IL-2 receptors. Because IL-2 receptors are present on the malignant T-cells but not on normal resting cells, clinical trials have been initiated in which patients with adult T-cell leukemia are being treated with either unmodified or toxin-conjugated forms of anti-Tac monoclonal antibody directed toward this growth factor receptor.
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PMID:The role of the multichain IL-2 receptor complex in the control of normal and malignant T-cell proliferation. 289 1


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