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)

Loss or down-regulation of human leukocyte antigen (HLA) class I expression has been demonstrated in a variety of solid tumors. To date, such altered HLA expression has not been studied extensively in freshly isolated leukemic blasts. If it occurs, leukemic cells could escape T-cell surveillance as a consequence. Genotypes of nine leukemic cell lines were determined using a polymerase chain reaction for HLA classes I and II. Cells were also examined for HLA beta2-microglobulin, and allele-specific HLA protein expression using flow cytometry. Next, 44 samples of freshly isolated leukemic blasts from 43 patients with malignant hematological diseases were examined for allele-specific HLA expression using flow cytometry. Microsatellite analysis was performed to determine heterozygosity in the HLA region on chromosome 6. Genotype analysis for HLA class I together with microsatellite analysis demonstrated loss of HLA haplotype in HL-60 cells. No loss of HLA haplotype was observed in 44 samples of freshly isolated leukemic blasts. As reported previously, flow cytometric analysis rarely demonstrated loss or down-regulation of HLA expression at initial diagnosis (3/39; 7.7%); however, this was evident in two of five cases in relapse (40.0%), which contrasts with previous reports. In one patient with acute leukemia, HLA-A2 cell surface expression was present at initial diagnosis, lost at relapse, and completely restored after 48 h of culture in the presence of interferon-gamma. These results suggest loss of allele-specific HLA expression may be involved in the pathogenesis of relapse in patients with leukemia. The findings should be valuable in designing new strategies for clinical immunotherapy.
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PMID:Loss or down-regulation of HLA class I expression at the allelic level in freshly isolated leukemic blasts. 1708 64

The reactivity of natural killer cells and some T-cell populations is regulated by killer immunoglobulin-like receptors (KIR) interactions with target cell HLA class I molecules. Such interactions have been suggested to influence outcomes after allogeneic hematopoietic stem cell transplantation, particularly for myeloid malignancies and with T-cell depletion. Donor KIR genotypes and recipient HLA KIR ligands were analyzed in 60 AML patients receiving T-cell replete, HLA-matched-related donor allogeneic bone marrow transplants. Patients were categorized according to their HLA inhibitory KIR ligand groups by determining whether or not they expressed: HLA-A3 or -A11; HLA-Bw4 and HLA-Cw groups (homozygous C1, homozygous C2 or heterozygous C1/C2). Heterozygous C1/C2 patients had significantly worse survival than those homozygous for C1 or C2 (5.8 vs 43.5 months, respectively, P=0.018) and the C1/C2 group had a higher relapse rate (47 vs 31%, respectively, P=0.048). Multivariate analysis found C1/C2 status to be an independent predictor for mortality (P=0.007, HR 2.54, confidence interval 1.29-5.00). C1/C2 heterozygosity was also associated with a delayed time to platelet engraftment, particularly for those with concurrent HLA-Bw4 expression (P=0.003). Since C1/C2 heterozygotes have a greater opportunity to engage inhibitory KIRs than do C1 or C2 homozygotes, they may more effectively inhibit KIR-positive NK- and T-cell populations involved in graft vs leukemia responses.
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PMID:Survival of AML patients receiving HLA-matched sibling donor allogeneic bone marrow transplantation correlates with HLA-Cw ligand groups for killer immunoglobulin-like receptors. 1731 Jan 34

In Ph(+) chronic myeloid leukemia (CML), the constitutively active Bcr-Abl kinase leads to the up-regulation and activation of multiple genes, which may subsequently result in the expression of leukemia-associated antigens. In this study, we investigated the immunogenicity of Bcr-Abl-regulated antigens by stimulating CD8(+) T lymphocytes with autologous dendritic cells transfected with RNA coding for Bcr-Abl wild-type or a kinase-deficient mutant. Significant HLA class I-restricted T-cell responses were detected against antigens regulated by the Bcr-Abl kinase, but not toward the Bcr-Abl protein itself. The T-cell repertoire of a patient with CML in major molecular remission due to imatinib mesylate was also dominated by T cells directed against Bcr-Abl-regulated antigens. These results encourage the development of immunotherapeutic approaches against Bcr-Abl-regulated antigens for the treatment of CML patients with residual disease following therapy with Bcr-Abl kinase inhibitors.
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PMID:The immunogenicity of Bcr-Abl expressing dendritic cells is dependent on the Bcr-Abl kinase activity and dominated by Bcr-Abl regulated antigens. 1757 86

In the present study, we attempted a comprehensive analysis of human leukocyte antigen (HLA) class I-bound peptides presented on adult T-cell leukemia (ATL) cells by the latest technology of mass spectrometry combined with reversed phase liquid chromatography (LC/MS) to identify novel tumor-associated antigens. We screened the sequenced peptides for those compatible with the motives of the respective HLA class I alleles. Then, we narrowed down the candidate peptides according to the differential expression of their source proteins between ATL cells and normal CD4 T cells. Among these candidates, we focused on cyclin-dependent kinaselike 5 (CDKL5) because it was highly expressed in several ATL cell lines and some ATL clinical samples but not in normal CD4 T cells. To examine its immunogenicity, we stimulated CD8 T cells from an HLA-B62 healthy donor several times with autologous monocyte-derived dendritic cells loaded with HLA-B*62-restricted CDKL5 peptide1012-1021 QVNQAALLTY that we identified. CDKL5-stimulated bulk CD8 T cells exerted higher cytotoxicity against CDKL5 peptide-loaded autologous Epstein Barr virus-transformed B cell line (LCL) than against unloaded LCL. Furthermore these T cells had strong cytotoxic activity against HLA-B*62-positive CDKL5-positive but not HLA-B*62-negative CDKL5-positive ATL cells. These results demonstrate that CDKL5 is a novel tumor (leukemia) antigen in ATL and that the HLA-B*62-restricted CDKL5 peptide can be used for cytotoxic T-lymphocyte-mediated immunotherapy. Identification of tumor-associated antigens by LC/MS is an eligible and efficient method suitable for future taylor-made immunotherapy of hematologic malignancies.
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PMID:Cyclin-dependent kinaselike 5 is a novel target of immunotherapy in adult T-cell leukemia. 1758 90

The effectiveness of T-cell-mediated immunotherapy of cancer depends on both an optimal immunostimulatory context of the therapy and the proper selection with respect to quality and quantity of the targeted tumor-associated antigens (TAA), and, more precisely, the T-cell epitopes contained in these tumor proteins. Our progressing insight in human leukocyte antigen (HLA) class I and class II antigen processing and presentation mechanisms has improved the prediction by reverse immunology of novel cytotoxic T lymphocyte and T-helper cell epitopes within known antigens. Computer algorithms that in silico predict HLA class I and class II binding, proteasome cleavage patterns and transporter associated with antigen processing translocation are now available to expedite epitope identification. The advent of genomics allows a high-throughput screening for tumor-specific transcripts and mutations, with that identifying novel shared and unique TAA. The increasing power of mass spectrometry and proteomics will lead to the direct identification from the tumor cell surface of numerous novel tumor-specific HLA class I and class II presented ligands. Together, the expanded repertoire of tumor-specific T-cell epitopes will enable more precise immunomonitoring and the development of effective epitope-defined adoptive T-cell transfer and multi-epitope-based vaccination strategies targeting epitopes derived from a wider diversity of TAA presented in a broader array of HLA molecules.
Leukemia 2007 Sep
PMID:Identification of T-cell epitopes for cancer immunotherapy. 1761 70

We applied a cDNA expression screening procedure with cryopreserved non-clonal CD8+ T cell populations (Lennerz et al., Proc. Natl. Acad. Sci. USA 102:16013-8, 2005) to the identification of candidate antigens for graft-versus-host disease (GvHD) and graft-versus-leukaemia (GvL) effects in allogeneic haematopoietic stem cell transplantation (allo-HSCT). In a patient-donor model system with HLA class I disparities, we identified an HLA-B*44 mismatch allele, HLA-B*4405, as the dominant target of alloreactive T cells expanded in vitro from donor peripheral blood mononuclear cells (PBMC). HLA-B*4405-reactive T cells were detectable after multiple in vitro stimulations in the patient's post-HSCT PBMC. In a patient-donor model with full HLA compatibility, the major target antigen of donor lymphocytes stimulated in vitro with the respective patient's pre-HSCT PBMC was restricted by HLA-A*0201 and was encoded by TRIM22-442 C, a newly detected polymorphic allele of the tripartite motif family member TRIM22 (synonym: STAF50), preferentially expressed in cells of the haematopoietic system. An arginine(R)-to-cysteine(C) exchange at position 442 generated an immunogenic T cell epitope equivalent to a minor histocompatibility antigen (mHag). TRIM22-442C-specific T cells persisted long-term in the patient's post-HSCT PBMC. Approximately, 1.3% of Caucasians carry TRIM22.442 C in association with HLA-A*0201. In particular, the knowledge of a large and diverse panel of such mHags may be crucial for further improvement of donor selection and adoptive T cell transfer strategies. The procedure applied herein will help to accelerate and facilitate their identification.
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PMID:Dissection and molecular analysis of alloreactive CD8+ T cell responses in allogeneic haematopoietic stem cell transplantation. 1800 63

The killer cell immunoglobulin-like receptors (KIRs) on NK cells recognize defined groups of HLA class I alleles. By this mechanism the NK cells fulfil a significant role in the first line of defense against infectious agents and cancer. For the treatment of leukaemia this NK cell allorecognition is of great importance. Still, an appropriate effect against the leukaemic cells requires sufficient expression of both KIR and HLA proteins. KIR gene polymorphism influence membrane expression of the KIR protein. We addressed KIR2DL4 gene polymorphism by a newly developed DNA and cDNA based direct sequencing based typing (SBT) and cloning approach. A panel of 44 individuals revealed a variety of KIR2DL4 alleles. Three new alleles have been identified, among those one allele showed alternatively spliced products. In conclusion, this approach is applicable for routine KIR2DL4 allele typing and enables the characterisation of new KIR2DL4 alleles.
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PMID:The elucidation of KIR2DL4 gene polymorphism. 1808 67

CD8(+) cytotoxic T-lymphocytes (CTLs) have been proven, in multiple animal models, to be the most powerful antiviral and antitumor components of the immune system. We have developed a protocol to activate and expand tumor and virus peptide-specific CD8(+) T-lymphocytes from the peripheral blood of healthy, human trophic leukemia virus-1 (HTLV-1) seronegative human leucocyte antigen (HLA)-A*0201 individuals. A combination of density-based separation and culture conditions was employed to isolate dendritic cells (DCs), which are the most potent antigen-presenting cells (APCs), and T-lymphocytes. The DCs were pulsed with HLA-A*0201 binding peptides and cultured with autologous T-lymphocytes to generate peptide-specific CTLs. The CTLs were generated against a nine-amino-acid peptide from the Tax protein of HTLV-1. The CTLs were expanded according to a restimulation schedule employing peptide-pulsed autologous monocytes and low-dose interleukin-2 (IL-2) to numbers in excess of 100 x 10(6) cells following 5 weeks of culture. Expanded cells contained primarily CD3(+) T-cells, of which CD8(+) T-lymphocytes constituted greater than two-thirds of the cell population. Obtained CTLs exhibited potent antigen-specific lysis of peptide-pulsed target cells in a dose-dependent fashion in in vitro (51)Cr release cytotoxicity assay. This antigen-specific killing was shown to be HLA class I restricted and mediated by CD8(+) T-lymphocytes. Since the T-lymphocytes were obtained from HTLV-1 seronegative donors, the generation of peptide-specific CTLs represents reliable and reproducible elicitation of a primary immune response in vitro against naive antigens and subsequent expansion of generated CTLs for adoptive immunotherapy. (c) 1996 John Wiley & Sons, Inc.
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PMID:Generation and ex vivo expansion of HTLV-1 specific CD8+ cytotoxic T-lymphocytes for adoptive immunotherapy. 1862 15

Transplantation of acute myeloid leukemia (AML) patients with grafts from related haploidentical donors has been shown to result in a potent graft-versus-leukemia effect. This effect is mediated by NK cells because of the lack of activation of inhibitory killer cell immunoglobulin-like receptors (KIRs) which recognize HLA-Bw4 and HLA-C alleles. However, conflicting results have been reported about the impact of KIR ligand mismatching on the outcome of unrelated HLA-mismatched hematopoietic stem cells transplants (HSCT) to leukemic patients. The interpretation of these conflicting results is hampered by the scant information about the level of expression of HLA class I alleles on leukemic cells, although this variable may affect the activation of inhibitory KIRs. Therefore in the present study, utilizing a large panel of human monoclonal antibodies we have measured the level of expression of HLA-A, -B and -C alleles on 20 B-chronic lymphoid leukemic (B-CLL) cell preparations, on 16 B-acute lymphoid leukemic (B-ALL) cell preparations and on 19 AML cell preparations. Comparison of the level of HLA class I antigen expression on leukemic cells and autologous normal T cells identified selective downregulation of HLA-A and HLA-B alleles on 15 and 14 of the 20 B-CLL, on 2 and 5 of the 16 B-ALL and on 7 and 11 of the 19 AML patients tested, respectively. Most interestingly HLA-C alleles were markedly downregulated on all three types of leukemic cells; the downregulation was most pronounced on AML cells. The potential functional relevance of these abnormalities is suggested by the dose-dependent enhancement of NK cell activation caused by coating the HLA-HLA-Bw4 epitope with monoclonal antibodies on leukemic cells which express NK cell activating ligands. Our results suggest that besides the HLA and KIR genotype, expression levels of KIR ligands on leukemic cells should be included among the criteria used to select the donor-recipient combinations for HSCT.
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PMID:Role of the inhibitory KIR ligand HLA-Bw4 and HLA-C expression levels in the recognition of leukemic cells by Natural Killer cells. 1884 61

Relapse after allo-SCT in patients with acute leukaemia remains a major problem. A beneficial impact of alloreactive natural killer (NK) cells has been reported for myeloid malignancies, but has been questionable for B-lineage ALL. We analysed lysis of primary paediatric precursor-B-ALL blasts by 285 NK cell clones to investigate whether HLA class I expression on the blasts and phenotypic killer cell Ig-like receptor (KIR) expression on NK cells affect the lytic activity against ALL blasts. Precursor-B-ALL blasts with low HLA-I expression were lysed by a majority (79%) of NK cell clones, whereas those with high HLA-I expression showed low susceptibility to NK clones independent of their KIR expression patterns. NK cell activity against susceptible blasts was regulated by differential surface expression of the three major KIRs (CD158a, CD158b, CD158e). NK clones with none of these three KIRs or a single KIR that recognized no ligand, were not inhibited by the targets and exerted higher lysis (P = <0.0005) in comparison to NK clones expressing KIRs with a ligand on the ALL blasts. In conclusion, the quantity of HLA-I expression on precursor-B-ALL blast regulates overall NK cell susceptibility; in case of reduced HLA expression, differential surface expression of KIRs affects NK cell alloreactivity against those blasts.
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PMID:Cytolytic activity of NK cell clones against acute childhood precursor-B-cell leukaemia is influenced by HLA class I expression on blasts and the differential KIR phenotype of NK clones. 1915 93


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