Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The staphylococcal enterotoxins SEA, SEB, SEC2, and TSST-1 bind to MHC class II molecules and stimulate polyclonal T cell populations on the basis of the expression of responsive TCR V beta domains. CL-1 is a human T cell clone that is specific for a peptide derived from influenza hemagglutinin (HA 307-319) presented in the context of HLA-DR1. CL-1 expresses the TCR V beta 13.1 domain, and does not respond to SEA, SEB, or TSST-1. This T cell was used to test the effect of nonstimulatory staphylococcal enterotoxins on a response to antigenic peptide. These toxins inhibit peptide-specific activation of CL-1 in a concentration-dependent manner. These toxins also inhibit the response of an HLA-DR1-specific alloreactive T cell clone. This inhibition seems to be a result of impaired access of TCR to the MHC/peptide complex rather than negative signaling by toxin via class II interaction or induction of T cell anergy. SEA, but neither SEB nor TSST-1 impedes avidin access to a biotin group attached to the amino terminus of HA 307-319. SEA partially impairs access of avidin to HA peptide biotinylated at residue 313, but is unable to inhibit avidin access to biotin at residue 318. This demonstrates that SEA binds to HLA-DR molecules that have also bound the antigenic peptide and suggests a topology for the interaction of SEA with class II, whereby the toxin interferes with peptide/MHC-TCR contact.
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PMID:Inhibition of antigen-specific T cell activation by staphylococcal enterotoxins. 782 79

The identification of antigenic peptides presented on the tumor cell surface by HLA class I molecules and recognized by tumor-specific cytotoxic T lymphocytes may lead to a peptide vaccine capable of inducing protective cellular immunity. We demonstrate that both HLA-A2-restricted breast and ovarian tumor-specific cytotoxic T lymphocytes recognize shared antigenic peptides. At least one of these peptides is derived from the oncogene product of HER2/neu, which is overexpressed in 30-40% of all breast and ovarian cancers. T cells sensitized against this nine-amino acid sequence demonstrate significant recognition of HLA-A2+, HER2/neu+ tumors. Since 50% of the tumor-cell population is HLA-A2+ and many different tumors express HER2/neu, this peptide may be widely recognized and have many clinical applications.
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PMID:Breast and ovarian cancer-specific cytotoxic T lymphocytes recognize the same HER2/neu-derived peptide. 783 5

We have recently shown that HLA-A2-restricted, tumor-specific CTL can be isolated from tumor-infiltrating lymphocytes (TIL) in ovarian cancer, and that the sensitivity of ovarian tumors to these CTL is correlated with HER2/neu expression. Furthermore, utilizing PCR, we have documented previously that V beta 2, V beta 3, V beta 6, and V beta 7 are represented in increased proportions in ovarian tumor-specific CTL lines. Therefore, to correlate the interaction of these specific TCR V beta segments with the HLA-A2 molecule and potential tumor-associated Ags (TAA) related to HER2/neu expression, we have utilized available mAbs to V beta 2, V beta 3, and V beta 6. We found that V beta 2+, V beta 3+, and V beta 6+ CTL mediate antitumor activity, and a combination of these mAbs resulted in 83 to 95% inhibition of the cytotoxicity against autologous tumor from three separate patients. These mAbs also were capable of blocking HLA-A2-matched allogeneic cytotoxicity, suggesting that all three V beta families recognize TAA in the context of HLA-A2. An HLA-A2+ melanoma was transfected with the HER2/neu gene and became sensitive to HLA-A2+ ovarian cancer-specific CTL lysis. This cytotoxicity was mediated by V beta 3+ and V beta 6+ CTL, as demonstrated by mAb-blocking studies. FACS-depletion studies confirmed that CTL populations depleted of V beta 3 or V beta 6 no longer could recognize the HER2/neu transfectant. We conclude that V beta 3 and V beta 6 recognize some TAA that are either derived from the HER2/neu protein or induced by the expression of the HER2/neu gene and presented in the context of HLA-A2. Furthermore, V beta 2 seems to recognize an HER2/neu-unrelated Ag system also presented by HLA-A2.
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PMID:TCR V beta 3+ and V beta 6+ CTL recognize tumor-associated antigens related to HER2/neu expression in HLA-A2+ ovarian cancers. 790 29

Previously, we have reported a correlation between the expression of HER2/neu and sensitivity to HLA-A2-restricted cytotoxic T-cells (CTL) in ovarian cancer. To investigate the role of HER2/neu in human non-small cell lung cancer (NSCLC), we established autologous tumor-specific CTL from tumor-infiltrating lymphocytes of HLA-A2+ HER2/neu+ NSCLC patients. These CTL lines specifically recognized HLA-A2+ HER2/neu+ autologous and allogeneic NSCLC cell lines as well as HLA-A2+ HER2/neu+ heterologous ovarian cancer cell lines. Furthermore, these CTL recognized an overexpressed, HER2/neu-derived peptide. From these results, we conclude that HLA-A2 serves as a restriction element in NSCLC. More importantly, at least one HER2/neu-derived peptide is a tumor-associated antigen in NSCLC and ovarian cancer.
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PMID:HER2/neu-derived peptides are shared antigens among human non-small cell lung cancer and ovarian cancer. 791 66

To study potential sources of tumor-associated Ags in human ovarian cancer, we have established two ovarian tumor cell lines (OvS1 and OvA2) from two ovarian cancer patients, which express the cellular oncogene HER2/neu. Corresponding tumor infiltrating lymphocyte cultures have also been established and display an autologous tumor-specific pattern of cytotoxicity that is HLA-A2 restricted. To determine the potential relationship between HER2/neu expression and CTL-mediated cytolysis, we first established tumor cell clones from OvS1. These were categorized as high or low expressors of HER2/neu (cOvS1+ or cOvS1-, respectively), and cOvS1+ clones displayed a significantly higher sensitivity to CTL killing as compared with cOvS1- clones. To modulate the expression of HER2/neu, ovarian cancer cells were treated with IFN-gamma. After this exposure, HER2/neu expression was significantly decreased, whereas the expression of HLA Class I was significantly increased. Despite the increase in HLA Class I molecules on the cell surface, CTL-mediated cytolysis of both OvS1 and OvA2 was significantly decreased. IFN-gamma treated cOvS1+ clones displayed a similar decrease in sensitivity to CTL killing, whereas IFN-gamma treated cOvS1- clones displayed an increase or no change in sensitivity to CTL. To confirm this apparent association between HER2/neu expression and CTL recognition, melanoma tumor cell lines that were insensitive to ovarian tumor-specific CTL were transfected with the HER2/neu gene. An HLA-A2+ HER2/neu-transfected melanoma cell line was made sensitive to HLA-A2 restricted ovarian tumor-specific CTL but not to HLA-A2 unrestricted CTL, whereas an HLA-A2- HER2/neu-transfected melanoma remained insensitive to HLA-A2 restricted CTL. These results demonstrate that the sensitivity of ovarian epithelial tumor cells to CTL-mediated lysis is associated with the level of expression of HER2/neu, suggesting that this oncogene product may serve as a source of tumor-associated Ags or as an inducer of such peptides. This is the first time in a human tumor system that oncogene expression has been related to the induction of antigenicity. These results prompt us to approach new strategies for immunotherapy of cancer.
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PMID:Association of HER2/neu expression with sensitivity to tumor-specific CTL in human ovarian cancer. 813 50

We report a successful allogeneic BMT for the treatment of juvenile chronic myelogenous leukemia (JCML) in a 9-month-old Laotian boy using an HLA-matched sibling donor with HbH disease (--SEA/aaCS). In addition, before BMT the recipient had a complex haemoglobinopathy associating heterozygous state AE along with HbH disease (--SEA/-a3,7) without haemoglobin Constant Spring (HbCS). Because various haemoglobinopathies are frequently encountered in southeast Asia, when BMT is performed in Asian families the results may be evaluated by the differing haemoglobin characteristics of recipient and donor. However, there is also a significant risk of transmitting a new haemoglobinopathy to the recipient. Because transplantation from HLA-identical siblings offers the only chance of cure for JCML, the presence of HbH disease with mild clinical expression in the donor should not be taken as a contra-indication to BMT.
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PMID:Donor for BMT with haemoglobin H disease. 837 39

We investigated the in vitro responsiveness of peripheral blood lymphocytes from two patients with T-cell chronic lymphocytic leukaemia (T-CLL) to Staphylococcus aureus enterotoxin (SE) superantigens. T-cell receptor (TcR) alpha beta (V beta 7.1)-expressing CD4+ leukaemic T cells from patient HE (white blood cell count 480,000/microliters) proliferated in response to SEA and, only at 1000-fold higher concentrations, to SEB, SED, and SEE. CD4+CD8+ TcR alpha beta (V beta 12.1)-expressing leukaemic T cells from patient KO (white blood cell count 120,000/microliters) were activated by SEB but not by the other tested SEs. In both instances, the activation of leukaemic T cells by SE was dependent on the presence of HLA-DR+ cells. Southern blot analysis of TcR beta gene rearrangement confirmed that the proliferating cells were derived from the leukaemic T-cell clone and not from contaminating normal T cells. These data indicate that leukaemic T cells from patients with T-CLL exert a clonally variable responsiveness to SE superantigens. We conclude that recognition of specific antigen and subsequent signal transduction can be initiated via the TcR of leukaemic T-CLL cells.
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PMID:Leukaemic T cells from patients with chronic lymphocytic leukaemia of T-cell origin respond to Staphylococcus aureus enterotoxin superantigens. 843 35

Human TCR gamma delta positive T cells can proliferate in response to stimulation with staphylococcal enterotoxins (SEs) or mediate lysis of SE pulsed target cells. In the small number of studies reported, the proliferative response of gamma delta T cells was limited to V gamma 9 negative cells and, in vitro, such responses do not require the presence of MHC class II molecules for antigen presentation. Proliferative responses have been found after stimulation with SEA, SEB and TSST. The cytolytic activity of gamma delta T cells can be mediated by two different mechanisms: either gamma delta T cells specifically interact with SEA pulsed target cells--this is most likely TCR mediated recognition--or gamma delta T cells mediate antibody dependent cellular cytotoxicity (ADCC). This latter reactivity depends on Fc-receptor expression by the gamma delta T cell clones and the presence of SE specific antibodies during the assay. So far cytotoxic gamma delta T cell reactivity has only been found against the highly homologous enterotoxins SEA and SEE. Finally, HLA-class II positive gamma delta T cell clones can present SE to other SE reactive T cells but appear to be relatively resistant to T cell mediated lysis. Taken together, TCR gamma delta positive T cells are able to respond to a number of bacterial superantigens and may therefore be involved in local immune responses to such antigens. This may be especially relevant for those gamma delta T cell subpopulations that are preferentially found in the (intestinal) epithelia where exposure to bacterial superantigens is likely to occur.
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PMID:Gamma delta T cell reactivity towards bacterial superantigens. 846 94

We have conducted a detailed structural analysis of 90 kilobases (kb) of the HLA Class III region from the Bat2 gene at the centromeric end to 23 kb beyond TNF. A single contig of 80 kb was sequenced entirely with a group of four smaller contigs covering 10 kb being only partly sequenced. This region contains four known genes and a novel telomeric potential coding region. The genes are bracketed by long, dense clusters of Alu repeats belonging to all the major families. At least six new families of MER repeats and one pseudogene are intercalated within and between the Alu clusters. The most telomeric 3.8 kb contains three potential exons, one of which bears strong homology to the ankyrin domain of the DNA binding factors NF kappa B and I kappa B.
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PMID:Dense Alu clustering and a potential new member of the NF kappa B family within a 90 kilobase HLA class III segment. 849 47

Ligation of major histocompatibility complex (MHC) class II antigens expressed on antigen-activated human CD4+ T-lymphocytes induces early signal transduction events including the activation of tyrosine kinases, the tyrosine phosphorylation of phospholipase-C gamma 1 and the mobilization of intracellular calcium. Similar responses have been observed in B-cells following stimulation of MHC class II molecules, including the increased production of intracellular cAMP. In this report, we demonstrate that the ZAP-70 tyrosine kinase is a responsive signaling element following cross-linking of HLA-DR in class II+ T-cells, and that the homologous tyrosine kinase p72syk is stimulated in B-cells following ligation of class II antigens. Antibody mediated co-ligation of the T-cell antigen receptor (TCR/CD3) with class II molecules resulted in augmented tyrosine phosphorylation of ZAP-70. Comparable to antibody induced receptor ligation, bacterial superantigen (SEA and SEB) treatment of HLA-DR+ T-cells stimulated ZAP-70 tyrosine phosphorylation, consistent with class II transmembrane signaling by ligation of HLA-DR and V beta in cis. Modulation of the TCR/CD3 led to abrogation of class II induced ZAP-70 tyrosine phosphorylation, but did not result in sequestering of ZAP-70 from the cellular cytoplasm. Hyperphosphorylated ZAP-70 was associated with TCR/CD3 zeta-chain following cross-linking of HLA-DR, suggesting a mechanism for the TCR/CD3-dependence of class II induced signals in alloantigen-activated human T-cells. In both tonsillar B-lymphocytes and B-cell leukemia lines, p72syk was rapidly phosphorylated on tyrosine residues following HLA-DR cross-linking. Tyrosine phosphorylation of p72syk induced through ligation of either the B-cell antigen receptor or class II molecules was potently inhibited by herbimycin A. MHC class II ligation on B-lymphocytes resulted in cell death, which was both qualitatively distinct from Fas-induced apoptosis and partially protected by herbimycin A pretreatment. Thus, ligation of MHC class II molecules expressed on human lymphocytes stimulates the ZAP-70/p72syk family of tyrosine kinases, leading functionally to a tyrosine kinase-dependent pathway of receptor-induced cell death.
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PMID:ZAP-70 and p72syk are signaling response elements through MHC class II molecules. 852 73


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