Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human retroviruses have recently been linked with T cell lymphoproliferative disorders and with the acquired immune deficiency syndrome. We investigated the mechanisms for acquired pure red cell aplasia and cutaneous anergy in a patient with the chronic T gamma-lymphoproliferative disease (T gamma-LPD) syndrome. Patient marrow erythroid progenitors (BFU-E) were 17 +/- 9% of control and were selectively increased to 88-102% of control after marrow T cell depletion. Patient Leu 2+ suppressor T cells spontaneously produced high titers of human gamma-interferon and resulted in a concentration-dependent selective inhibition (74-91%) of BFU-E when co-cultured with autologous or allogeneic marrow. Conditioned media (CM) derived from patient Leu 2+ T cells similarly inhibited growth of autologous or allogeneic marrow BFU-E. The inhibitory factor derived from patient CM was acid-labile (pH 2) and sensitive to trypsin; prior treatment of patient T cells with anti-HLA-DR monoclonal antibody plus complement abrogated the suppressive effect of T cell-derived CM. Patient peripheral blood mononuclear cells (PBMC) were unable to support growth of cultured interleukin 2 (IL 2)-dependent T cells, but responded to exogenous IL 2 in vitro with a 16-21-fold augmentation, relative to control, in mitogen-induced proliferation. Antibodies to HTLV-I core proteins p19 and p24 but not to HTLV-III proteins were detected in patient serum by Western blotting; patient cultured PBMC stained (7-11%) with antibodies to p19 and p24. Patient cultured PBMC demonstrated integrated HTLV-I genomic sequences by the Southern technique and expressed both specific HTLV-I genomic sequences by RNA dot blot plus reverse transcriptase activity. Utilizing a cloned DNA probe for the beta chain of the T cell receptor gene, patient PMBC demonstrated gene rearrangements providing presumptive evidence for clonality. The presence in serum of HTLV-I p19 and p24 antibodies, the expression of p19 and p24 core antigens on patient mononuclear cells, the evidence of HTLV-I proviral integration sequences and the expression of HTLV-I genomic sequences in patient cells, indicates infection with HTLV-I and raises the possibility of an etiologic link between human retrovirus infection and some instances of large granular lymphocytic leukemia (T gamma-LPD).
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PMID:Human T cell leukemia virus-I-associated T-suppressor cell inhibition of erythropoiesis in a patient with pure red cell aplasia and chronic T gamma-lymphoproliferative disease. 289 60

The cyclin-dependent kinase 4 (cdk4) inhibitor (p16INK4/MTS1/CDKN2) gene has been recently identified as a putative tumor suppressor gene because of the high frequency of homozygous deletion observed in numerous human tumor cell lines, including leukemias. However, results obtained from uncultured tumor samples have led to discussion of the relevance of these findings. Using reverse transcriptase polymerase chain reaction (RT-PCR) and Southern blot analysis, we have investigated p16INK4A gene at both RNA and genomic levels in various types of leukemias: acute myeloid leukemia (AML) (n = 23); acute lymphocytic leukemia (ALL) (n = 22) and B cell chronic lymphoproliferative disorders (CLPD) (n = 33). p16INK4A mRNA expression was not found in only 1/20 AML and 2/23 CLPD samples. Conversely, p16INK4A mRNA was not detected in 5/17 ALL cases, and intensity of PCR products were barely detectable in seven additional cases, possibly related to the contamination by normal cells in some cases. By Southern blotting, a homozygous deletion of p16INK4A gene was found in 6/17 ALL cases (35%) among which 4/6 were negative or weakly positive by RT-PCR assay. None of the five AML and 20 CLL samples studied had p16INK4A deletion. Sequence analysis of p16INK4A exon 2 did not show point mutation in two of these cases lacking mRNA expression. Our data provide further evidence that among hematological malignancies, ALL are the most likely to be associated with p16INK4A inactivation, mainly by homozygous gene deletion. Since most hematological malignancies-except ALL-are infrequently associated with p16INK4A and retinoblastoma (Rb) gene alteration it seems worthwhile to explore cdk4 and cdk6 expression to determine whether or not the disruption of the p16INK4A/Rb/cdk4/cdk6 regulatory loop might play a role in their pathogenesis.
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PMID:Alterations of cyclin-dependent kinase 4 inhibitor (p16INK4A/MTS1) gene structure and expression in acute lymphoblastic leukemias. 763 Jan 99

Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare haematological disorder. It is characterized by activated and morphologically atypical B lymphocytes and polyclonal IgM production and has been associated with female sex, cigarette smoking, and HLA-DR7 expression. We report a case of PPBL with intermitting symptoms compatible with a chronic fatigue syndrome, recurrent erythema nodosum and multiforme. Serological findings suggested a chronic active Epstein-Barr virus (EBV) infection. Messenger RNA of EBV immediate early gene transactivation BZLF1 was detected in peripheral blood lymphocytes by reverse transcriptase PCR indicating a persistent replication of the virus. Over 2 years of observation we detected varying numbers of atypical lymphocytes. These cells hybridized with a probe specific for the EBV internal repeat region (BamHI W) which indicates a productive infection. Of interest, no reaction was observed with a probe specific for the latency-associated small RNAs (EBERs). The immunological phenotype of the polyclonal B cells was similar to B-cell lines immortalized by EBV in vitro, expressing a number of activation molecules (CD23, CD25, CD54) and the bcl-2 protein. In summary, our findings suggest that persistent EBV replication might be crucial in the development of lymphoproliferative disorders such as PPBL.
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PMID:Chronic active Epstein-Barr virus disease in a case of persistent polyclonal B-cell lymphocytosis. 764 89

The recently discovered cytokine, interleukin-15 (IL-15), has been demonstrated to share several biologic properties with IL-2 in different cell systems, including T-cell and natural killer (NK) cell compartments. As for B lymphocytes, IL-15 has been shown to provide stimulatory activities in normal preactivated B cells that are mainly transduced through IL- 2 receptor (IL-2R) complex components. Since leukemic B cells from patients with chronic lymphoproliferative disorders (CLD) bear IL-2R and grow in response to IL-2, we investigated whether IL-15 triggers the proliferation of malignant B cells obtained from 12 patients with B-cell chronic lymphocytic leukemia (B-CLL) and five patients with hairy cell leukemia (HCL). Enriched B cells recovered from five healthy subjects were also studied as controls. IL-15 stimulated the proliferation of freshly isolated leukemic B cells, but not resting normal B lymphocytes, the latter being able to grow in the presence of IL-15 only after in vitro preactivation with phorbol myristate acetate. The proliferation elicited by IL-2 on leukemic cells was comparable to that determined by IL-15. Following addition of graded concentrations of IL-15 to low/intermediate-dose IL-2, resting leukemic B cells showed a higher stimulatory rate than that observed using the two cytokines separately. In normal resting B lymphocytes, this cumulative effect was not observed. The role of different IL-2R subunits in IL-15-driven growth of malignant B cells was investigated both by their expression on leukemic cells and by the block of different IL-2R subunits (p55, p75, and p64) with specific monoclonal antibodies (MoAbs). Using flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses we demonstrated that both B-CLL and HCL leukemic B cells express the beta and gamma chains of the IL-2R system. The stimulatory activity achieved by IL-15 decreased significantly, blocking the beta and gamma chains of the IL-2R. Taken together, these findings demonstrate that IL-15 triggers the growth of leukemic B cells through IL-2R system subunits, pointing to the role of this novel cytokine in regulating the neoplastic proliferation in CLD.
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PMID:Interleukin-15 promotes the growth of leukemic cells of patients with B-cell chronic lymphoproliferative disorders. 860 49

Primary cutaneous CD30+ lymphoproliferative disorders (LPDs), including lymphomatoid papulosis (LyP), anaplastic and nonanaplastic CD30+ large-cell lymphoma, and borderline cases, comprise a clinical and histologic spectrum. Primary cutaneous and primary nodal CD30+ anaplastic large-cell lymphomas (ALCLs) are distinct clinical entities that have identical morphologic features but differ in age of onset, immunophenotype, and prognosis. It can be difficult to distinguish primary cutaneous from nodal ALCLs that secondarily involve the skin, which is important because these diseases differ significantly in response to treatment and clinical outcome. The t(2;5) chromosomal translocation is highly associated with primary CD30+ ALCL of nodal origin. The possible occurrence of t(2;5) in primary cutaneous CD30+ LPDs has not been studied extensively, and it remains to be determined if expression of this translocation can be used to distinguish primary cutaneous ALCL from nodal ALCL that secondarily involves the skin. To address these issues, we studied 43 cases of cutaneous and nodal CD30+ LPDs using reverse transcriptase-polymerase chain reaction (RT-PCR) and/or immunohistochemistry. We found no evidence for the t(2; 5) translocation in 14 cases of primary cutaneous CD30+ LPDs, which included 10 cases of LyP, three cases of primary cutaneous CD30+ ALCL, and one borderline case. These findings were in marked contrast to CD30+ ALCL of nodal origin, in which 19 of 29 (66%) cases were positive for t(2;5), including all five cases with secondary skin involvement. Our results support the hypothesis that (1) primary cutaneous CD30+ LPDs (including LyP) and primary nodal ALCL are distinct diseases that differ in clinical behavior and pathogenesis and (2) differential expression of t(2;5) can help to distinguish between primary cutaneous CD30+ LPDs and ALCL of nodal origin.
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PMID:The t(2;5) chromosomal translocation is not a common feature of primary cutaneous CD30+ lymphoproliferative disorders: comparison with anaplastic large-cell lymphoma of nodal origin. 887 25

The t(2;5) (p23;q35) chromosomal translocation has been found in a high proportion of lymph node-based CD30+ large cell lymphomas of T-cell lineage. This translocation is believed to result in the expression of a fusion protein containing the catalytic domain of anaplastic lymphoma kinase (ALK) under the control of the promoter for nucleophosmin, a nucleolar phosphoprotein. Expression of ALK activity, which does not normally occur in lymphocytes, is postulated to be involved in the pathogenesis of lymphomas bearing the t(2;5) translocation. Several primary cutaneous lymphoproliferative disorders and Hodgkin's disease are also known to contain CD30+ large lymphoid cells. To determine the role of the t(2;5) translocation in these diseases, we developed a DNA-based polymerase chain reaction (PCR)/Southern blot assay to detect this translocation at the genomic level in lymphomatoid papulosis (14 cases), primary cutaneous CD30+ large cell lymphoma of T-lineage (10 cases) and Hodgkin's disease (13 cases). Two cases of pityriasis lichenoides were also studied. The t(2;5) translocation was not present in any of these specimens. To determine if some other somatic mutation might have resulted in inappropriate expression of ALK catalytic domain, we devised an RNA-based reverse transcriptase-PCR assay to detect transcripts encoded by this ALK region. None were found in the six additional cases of lymphomatoid papulosis that were studied. In aggregate, these results strongly suggest that inappropriate expression of ALK is not involved in the pathogenesis of these CD30+ lymphoproliferative disorders, and that lymph node-based CD30+ large cell lymphoma is a disease that is biologically distinct from skin-based CD30+ lymphoproliferative disorders and Hodgkin's disease. Using methods developed for this report, we also cloned and sequenced the t(2;5) genomic junctional sequences present in the SUP-M2 and SU-DHL-1 cell lines. These intron sequences will be useful for mapping t(2;5) breakpoint clusters.
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PMID:Lack of the t(2;5) or other mutations resulting in expression of anaplastic lymphoma kinase catalytic domain in CD30+ primary cutaneous lymphoproliferative disorders and Hodgkin's disease. 878 33

Primary cutaneous CD30 (Ki-1)+ large cell lymphoma (KiL) and lymphomatoid papulosis (LyP) type A are collectively termed as primary cutaneous CD30-positive lymphoproliferative disorders. We examined the cytokine profile of skin-infiltrating cells and the therapeutic efficacy of recombinant interferon-gamma (rIFN-gamma) in primary cutaneous KiL and LyP type A. By reverse transcriptase-polymerase chain reaction, mRNAs for interleukin-4 (IL-4) and IL-10 were detected in the dermis of skin lesions in all cases (three cases of KiL and four cases of LyP). In addition, tissue from one KiL patient transcribed IL-2 and IFN-gamma messages, and one LyP patient showed IL-2 mRNA. In contrast, normal skin from ten healthy donors contained mRNA for IL-2 or IFN-gamma, or both, but not for IL-4. Before the therapeutic trial of rIFN-gamma, the response of skin lesions was assessed by a predictive skin test with local injection of rIFN-gamma (0.5 x 10(6) Japan Reference Units [JRU; 1 JRU roughly corresponds to 4 NIH units]) for 3 consecutive days in two KiL and two LyP patients. Numbers of skin-infiltrating CD30+ cells were decreased, and transcription of mRNA for IL-4 and IL-10 was downregulated after the skin test in one KiL and two LyP cases. One KiL patient showed no histologic response or change in mRNA expression. In the therapeutic trial, rIFN-gamma (total doses of 1.2-4.0 x 10(7) JRU) was administered intravenously (n = 2) or locally (n = 2). In three patients who responded to the skin test, the lesions were objectively improved and the numbers of skin-infiltrating CD30+ cells were markedly decreased after the therapeutic trial. No improvement was observed in one KiL patient who did not respond to the skin test. These findings suggest that the skin-infiltrating CD30+ cells in KiL and LyP have a Th2 cytokine profile and raise the possibility that the administration of rIFN-gamma improves the conditions by inhibiting cytokine mRNA transcription and proliferation of CD30+ cells.
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PMID:Th2 cytokine mRNA expression in primary cutaneous CD30-positive lymphoproliferative disorders: successful treatment with recombinant interferon-gamma. 894 69

Lymphoproliferative disorders involving Epstein-Barr virus (EBV) infected natural killer (NK) cells are reported with increasing frequency, but the nature and role of EBV infection in these cells remains undefined. In this study, we have investigated virus-cell interactions in the EBV-positive YTN10 cell line, an NK-like cell line established from a patient with lymphoblastic lymphoma. Low level expression of the EBV receptor CD21 molecule was detected by FACS and reverse transcriptase polymerase chain reaction (RT-PCR) analysis. Immunoblotting and RT-PCR analysis identified a latency II pattern of EBV gene expression, consisting of EBNA-1 transcription from the Qp promoter, in the absence of other EBNA gene expression, and accompanied by LMP-1 and LMP-2A expression. The EBV genome was present in episomal form and there was evidence for lytic viral replication. This latency pattern is typical of EBV gene expression in nasopharyngeal carcinoma and Hodgkin's disease, and differs from the full spectrum of EBV latent gene expression in most posttransplant lymphoproliferative disorders and from the restricted EBNA-1 expression in Burkitt's lymphoma tissues. The interaction between EBV and NK cells described here has important implications for the pathogenesis and treatment of EBV-infected NK malignancies.
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PMID:Virus-cell interactions in a natural killer-like cell line from a patient with lymphoblastic lymphoma. 897 60

Human herpesvirus-8 (HHV-8) has been described in association with two lymphoproliferative disorders: one benign, multicentric Castleman's disease (MCD), and one malignant, primary effusion lymphoma (PEL). The factors that lead to malignant transformation of lymphoid cells are unknown, although most cases of PEL also are positive for EBV, suggesting a role for EBV as a cofactor in malignant transformation. We encountered a rare case of an HHV-8-associated MCD, followed by the development of an HHV-8-positive pleural PEL and a gastric large cell lymphoma in an HIV-seronegative male patient. The lesions were negative for Epstein-Barr virus (EBV). The combination of these diverse HHV-8-associated lymphoproliferative disorders in a single patient afforded us the ability to study potential differences in gene expression in these conditions. HHV-8 DNA was demonstrated by PCR in lymphoid tissues involved by MCD and PEL. By reverse transcriptase-PCR, HHV-8-related transcripts, including vG-coupled protein receptor, vbcl2, vcyclin D, vIL-6, vMIPI, and vMIPII, were detected in the PEL from the pleural cavity and the gastric lymphoma, whereas these transcripts, except for vIL-6, were not detected in a lymph node biopsy with MCD. Expression of hIL-10 was weak in the PEL from the pleural cavity, and expression of hIL-6 was undetectable in all three lesions. These data suggest that vIL-6 may be integral to the pathogenesis of MCD, whereas other viral transcripts that encode oncogene and chemokine homologues are important for HHV-8 tumorigenicity.
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PMID:Expression of human herpesvirus-8 oncogene and cytokine homologues in an HIV-seronegative patient with multicentric Castleman's disease and primary effusion lymphoma. 988 64

Human herpesvirus-8 (HHV-8) genome encodes for genes homologous to human cellular genes such as interleukin-6 (IL-6), Cyclin-D, BCL-2, and IL-8 receptor (G-protein-coupled receptor [GCR]). We used reverse transcriptase-polymerase chain reaction to study the expression of these viral genes in lymphoproliferative disorders associated with HHV-8 infection. None of these genes was expressed in 1 case of benign, localized Castleman's disease (CD), and only viral IL-6 and viral Cyclin-D were transcribed in 2 cases of benign lymphadenopathies with giant germinal center hyperplasia and increased vascularity. In contrast, all 4 genes were transcribed in 1 case of multicentric CD of plasma cell type with aggressive clinical course and in 1 primary effusion lymphoma cell line. Our study provides the evidence that various HHV-8 genes, homologous to cellular genes involved in control of proliferation and apoptosis, may be differently expressed in different lymphoid disorders in vivo.
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PMID:Expression of cell-homologous genes of human herpesvirus-8 in human immunodeficiency virus-negative lymphoproliferative diseases. 1051 99


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