Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human T-cell leukemia virus type 1 (HTLV-1) establishes a persistent infection in the host despite a vigorous virus-specific immune response. Here we demonstrate that an HTLV-1-encoded protein, p12(I), resides in the endoplasmic reticulum (ER) and Golgi and physically binds to the free human major histocompatibility complex class I heavy chains (MHC-I-Hc) encoded by the HLA-A2, -B7, and -Cw4 alleles. As a result of this interaction, the newly synthesized MHC-I-Hc fails to associate with beta(2)-microglobulin and is retrotranslocated to the cytosol, where it is degraded by the proteasome complex. Targeting of the free MHC-I-Hc, and not the MHC-I-Hc-beta(2)-microglobulin complex, by p12(I) represents a novel mechanism of viral interference and disrupts the intracellular trafficking of MHC-I, which results in a significant decrease in surface levels of MHC-I on human T-cells. These findings suggest that the interaction of p12(I) with MHC-1-Hc may interfere with antigen presentation in vivo and facilitate escape of HTLV-1-infected cells from immune recognition.
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PMID:Free major histocompatibility complex class I heavy chain is preferentially targeted for degradation by human T-cell leukemia/lymphotropic virus type 1 p12(I) protein. 1139 Jun 10

The recently recognized translocation t(12;21)(p13;q22), which results in the ETV6-AML1 fusion product, is the most common genetic rearrangement found in childhood pre-B acute lymphoblastic leukaemia (ALL). It has been associated with a more favourable prognosis and a distinct immunophenotype in terms of myeloid and B cell-associated antigen expression. Using flow cytometry, we investigated whether the unique ETV6-AML1 phenotype extended to molecules associated with antigen presentation by analysing 50 diagnostic bone marrow samples from paediatric pre-B ALL patients. Reverse transcription polymerase chain reaction for the ETV6-AML1 fusion transcript was positive in 14 patients. ETV6-AML1-positive samples were characterized by a significantly higher expression of the co-stimulatory molecule CD40 (P < 0.0001), as well as a significantly higher class II HLA-DR mean channel fluorescence (P = 0.001). In contrast, CD86 expression was significantly lower on fusion-positive samples (P = 0.010) while there was no difference in expression of CD80 or major histocompatibility complex class I between ETV6-AML1-positive and -negative samples. This is the first observation in acute leukaemia that the distinct immunophenotype associated with specific translocations includes the expression of molecules associated with antigen presentation. In the case of ETV6-AML1 pre-B ALL, this characteristic immunophenotype may have implications for the immunogenicity of the leukaemic cells.
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PMID:ETV6 (TEL)-AML1 pre-B acute lymphoblastic leukaemia cells are associated with a distinct antigen-presenting phenotype. 1184 26

Numerous animal and clinical studies have shown that injection of T lymphocytes from a major histocompatibility complex matched donor can cure subjects with chemotherapy-resistant hematological malignancies. This graft-versus-tumor effect, which represents the most conclusive evidence that the immune system can cure cancer in humans, is mediated primarily if not exclusively by T cells specific for host minor histocompatibility antigens. Since minor histocompatibility antigens are present on all tissues and organs, injection of unselected donor T cells also causes graft vs. host disease, which drastically limits the use and benefits of this treatment. Recent studies in mice have shown that adoptive transfer of primed T cells targeted to a single major histocompatibility complex class I restricted immunodominant minor histocompatibility antigen can eradicate leukemia cells without causing any toxicity to the host. We present the promises and caveats of this and other new approaches for adoptive T cell immunotherapy of cancer.
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PMID:Adoptive cancer immunotherapy: discovering the best targets. 1197 30

Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL) in infected individuals after a long incubation period. Despite the apparent transforming ability of HTLV-1 under experimental conditions, most HTLV-1 carriers are asymptomatic. These facts suggest that HTLV-1 is controlled by host immunity in most carriers. To understand the interplay between host immunity and HTLV-1-infected cells, in this study, we isolated several HTLV-1 Tax-specific cytotoxic T-lymphocyte (CTL) lines from rats inoculated with Tax-coding DNA and investigated the long-term effects of the CTL on syngeneic HTLV-1-infected T cells. Our results demonstrated that long-term mixed culture of these CTL and the virus-infected T cells led to the emergence of CTL-resistant HTLV-1-infected cells. Although the Tax expression level in these resistant cells was equivalent to that in the parental cells, expression of surface major histocompatibility complex class I (MHC-I) was significantly downregulated in the resistant cells. Downregulation of MHC-I was more apparent in RT1.A(l), which presents a Tax epitope recognized by the CTL established in this study. Moreover, peptide pulsing resulted in killing of the resistant cells by CTL, indicating that resistance was caused by a decreased epitope density on the infected cell surface. This may be one of the mechanisms for persistence of HTLV-1-infected cells that evade CTL lysis and potentially develop ATL.
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PMID:Correlation of major histocompatibility complex class I downregulation with resistance of human T-cell leukemia virus type 1-infected T cells to cytotoxic T-lymphocyte killing in a rat model. 1207 1

The rat monoclonal antibody LMR-12 was shown earlier to react with a plasma membrane protein, upregulated in multidrug-resistant cell lines. In this study, we observed distinct LMR-12 staining in 36 out of 55 non-drug-selected tumour cell lines, including melanomas, renal cell-, colon- and lung carcinomas, whereas in other tumour types, such as leukaemia and ovarian cancer, LMR-12 staining was generally low or absent. The cDNA encoding the LMR-12 antigen was isolated from a library of the multidrug-resistant human fibrosarcoma cell line HT1080/DR4 by expression cloning in MOP8 cells. Sequence analysis showed that the LMR-12 antigen is identical to the major histocompatibility complex class I molecule beta 2-microglobulin (beta2-m). The LMR-12/ beta2-m staining results were confirmed by mRNA microarray data from an independent National Cancer Institute study, as well as by newly obtained reverse transcriptase polymerase chain reaction data. Further analysis of the microarray data showed that beta2-m levels closely reflected levels of major histocompatibility complex class I heavy chains and the transporter associated with antigen processing. Since the ABC transporter associated with antigen processing was previously shown to contribute to multidrug-resistance, it may very well be that the observed LMR-12/ beta2-m levels are secondary to (elevated) levels of the transporter associated with antigen processing. A perspective arising from the present study is that drug resistant tumour cells may, by having elevated levels of major histocompatibility complex related molecules, be particular good candidates for alternative therapeutic therapies, such as cytotoxic T cell mediated immune-therapies.
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PMID:Increased expression of beta 2-microglobulin in multidrug-resistant tumour cells. 1208 91

In mice, donor leukocyte infusion (DLI) given to established mixed allogeneic chimeras can mediate powerful graft-versus-host (GVH) reactions confined to the lymphohematopoietic system without inducing graft-versus-host disease (GVHD). In a clinical trial attempting to capture this approach to achieve graft-versus-leukemia/lymphoma (GVL) effects without GVHD, we have observed surprisingly powerful antitumor effects of DLI in patients achieving mixed chimerism after nonmyeloablative bone marrow transplantation. This observation led us to hypothesize that host antigen-presenting cells in mixed chimeras might be required to optimally present recipient antigens to the donor lymphocytes, leading to maximal graft-versus-tumor effects. To test this hypothesis, we established mixed and fully allogeneic hematopoietic chimeras in B6 mice and evaluated the effect of DLI on EL4 T-cell lymphoma. DLI administration to mixed chimeras produced dramatically improved leukemia-free survival compared to administration of DLI to full donor chimeras. DLI also converted mixed chimeras to full chimeras without causing GVHD. The magnitude of the GVL effect was dependent on the level of major histocompatibility complex class I expression on recipient hematopoietic cells in mixed chimeras. Thus, the induction of mixed chimerism followed by delayed DLI provides an approach to inhibiting GVHD that optimizes GVL effects.
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PMID:Donor lymphocyte infusions mediate superior graft-versus-leukemia effects in mixed compared to fully allogeneic chimeras: a critical role for host antigen-presenting cells. 1217 15

Cell membrane localization of the 72 kDa heat shock protein 70 (Hsp70) has been found on different tumour cell lines, on biopsy material from solid tumours and metastases and on leukaemic blasts from acute myelogenous leukaemia patients, but not on the corresponding normal tissues, as determined by flow cytometry using the Hsp70-specific monoclonal antibody C92F3B1. In the present study Hsp70 membrane expression was studied on primary malignant melanomas, melanoma metastases, melanocytes, human skin fibroblasts and peripheral blood lymphocytes, together with expression of the melanoma-associated markers Mel-1, Mel-2 and Mel-5, major histocompatibility complex class I and the fibroblast-specific marker ASO2. As previously shown, fibroblasts and peripheral blood lymphocytes from healthy human volunteers were found to be negative for Hsp70 and for the melanoma-associated markers Mel-1, Mel-2 and Mel-5. Human melanocytes from healthy human donors were also negative for Hsp70, but were positive for Mel-1 and Mel-5. Independent of the Clark's level, all the malignant melanomas (n = 9) and metastases (n = 11) exhibited were positive for both Mel-1 and Mel-2. The primary melanomas could be divided into two groups according to their Hsp70 and Mel-5 expression pattern: those with an Hsp70-negative and a Mel-5-positive phenotype (-/+) (five out of nine), and those with an Hsp70-positive and a Mel-5-negative phenotype (+/-) (four out of nine). All the melanoma metastases (n = 11) had an Hsp70-positive, Mel-5-negative phenotype (+/-). These data provide the first hint that the marker combination Hsp70 positive/Mel-5 negative might be useful in estimating the metastatic potential of a melanoma. Investigations on changes in the marker combination Hsp70/Mel-5 during onset of melanoma disease and progression will clarify its potential as a prognostic risk factor.
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PMID:Heat shock protein 70 membrane expression and melanoma-associated marker phenotype in primary and metastatic melanoma. 1269 Feb 97

The addition of specific cytokines is a mandatory prerequisite for the generation and subsequent function of leukaemia-derived dendritic cells (DC) believed to induce specific T-cell responses. In this study, we report the ability of blasts derived from cytogenetically classified acute myeloid leukaemia (AML) cells with the inversion of chromosome 16 to stimulate allogeneic and autologous T cells without additional cytokines. They displayed a measurable immunogenic effect. Sixteen of 17 established, stable AML cell lines, growing primary tumour cells from patients with a variety of chromosomal abnormalities, altered their surface marker expression pattern in proliferating culture. They lost the progenitor markers CD33, CD13 and CD34 while significantly increasing expression of the co-stimulatory molecules CD80 and CD86. Four cell lines derived from inv(16) positive blasts mounted allogeneic as well as autologous T cell activation with concomitant expression of CD25 and CD69. Moreover, oligoclonal expanded T cells were able to lyse inv(16) AML blasts in a specific major histocompatibility complex class I-restricted and CD80-dependent manner. AML blasts with karyotypes other than inv(16) activated T cells, but without inducing a significant proliferation. We conclude from this study that AML blasts derived from inv(16) positive patients may be preferential targets for AML immunotherapy strategies.
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PMID:Core-binding factor-beta positive acute myeloid leukaemia cells induce T-cell responses. 1463 72

Graft-versus-host disease (GVHD) is a major source of morbidity in allogenic stem cell transplantation. We previously showed that recipient antigen-presenting cells (APCs) are required for CD8-dependent GVHD in a mouse model across only minor histocompatibility antigens (minor H antigens). However, these studies did not address the function of donor-derived APCs after GVHD is initiated. Here we show that GVHD develops in recipients of donor major histocompatibility complex class I-deficient (MHC I(-)) bone marrow. Thus, after initial priming, CD8 cells caused GVHD without a further requirement for hematopoietic APCs, indicating that host APCs are necessary and sufficient for GHVD. Nonetheless, GVHD was less severe in recipients of MHC I(-) bone marrow. Therefore, once initiated, GVHD is intensified by donor-derived cells, most probably donor APCs cross-priming alloreactive CD8 cells. Nevertheless, donor APCs were not required for CD8-mediated graft-versus-leukemia (GVL) against a mouse model of chronic-phase chronic myelogenous leukemia. These studies identify donor APCs as a new target for treating GVHD, which may preserve GVL.
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PMID:Donor APCs are required for maximal GVHD but not for GVL. 1528 85

Rheumatoid arthritis (RA) is an autoimmune disease affecting approximately 1% of the population worldwide. Previously, we showed that human T-cell leukemia virus type I-transgenic mice and interleukin-1 receptor antagonist-knockout mice develop autoimmunity and joint-specific inflammation that resembles human RA. To identify genes involved in the pathogenesis of arthritis, we analyzed the gene expression profiles of these animal models by using high-density oligonucleotide arrays. We found 1,467 genes that were differentially expressed from the normal control mice by greater than threefold in one of these animal models. The gene expression profiles of the two models correlated well. We extracted 554 genes whose expression significantly changed in both models, assuming that pathogenically important genes at the effector phase would change in both models. Then, each of these commonly changed genes was mapped into the whole genome in a scale of the 1-megabase pairs. We found that the transcriptome map of these genes did not distribute evenly on the chromosome but formed clusters. These identified gene clusters include the major histocompatibility complex class I and class II genes, complement genes, and chemokine genes, which are well known to be involved in the pathogenesis of RA at the effector phase. The activation of these gene clusters suggests that antigen presentation and lymphocyte chemotaxis are important for the development of arthritis. Moreover, by searching for such clusters, we could detect genes with marginal expression changes. These gene clusters include schlafen and membrane-spanning four-domains subfamily A genes whose function in arthritis has not yet been determined. Thus, by combining two etiologically different RA models, we succeeded in efficiently extracting genes functioning in the development of arthritis at the effector phase. Furthermore, we demonstrated that identification of gene clusters by transcriptome mapping is a useful way to find potentially pathogenic genes among genes whose expression change is only marginal.
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PMID:Identification of arthritis-related gene clusters by microarray analysis of two independent mouse models for rheumatoid arthritis. 1680 6


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