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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Natural killer (NK) cell activity and related markers were analysed in childhood acute lymphoblastic leukaemia (ALL). Children with untreated ALL, children with active disease, and children in remission for less than 1 month and undergoing induction therapy had significantly lower NK cell activity in peripheral blood than the control group (P less than 0.05, P = 0.0005, and P less than 0.0025). Patients in remission for 1-3 months and undergoing consolidation chemotherapy had normal NK activity (P greater than 0.05). Children in complete remission for more than 3 months and undergoing maintenance therapy also had a normal NK activity in their peripheral blood (P greater than 0.05). However, their bone marrow cells showed an increased NK cell activity (P less than 0.0005). Cells positive for the Leu-7 marker were reduced in the peripheral blood from untreated children (P less than 0.025) and children in remission for less than 1 month (P = 0.025). The percentage of cells from peripheral blood expressing the marker Leu-11b (CD 16) did not differ significantly from that of the controls (P greater than 0.05). However, children in complete remission for more than 3 months had a higher number of bone marrow cells expressing the Leu-7 (P = 0.005) and the Leu-11b (CD 16) markers (P = 0.05) than controls. Stimulation of mononuclear cell suspensions with recombinant alpha interferon and recombinant interleukin 2 were shown to cause a normalization of the NK cell activity in peripheral blood and bone marrow.
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PMID:Increased natural killer cell activity and numbers of Leu-7 and Leu-11b (CD 16)-positive cells in bone marrow of children in remission from acute lymphoblastic leukaemia. 246 27

An adoptive therapy model has been utilized to examine the requirements for T cells to promote eradication of a disseminated, retrovirus-induced, syngeneic leukemia. Complete tumor elimination required that the transferred T cells proliferate in the host and mediate an anti-tumor effect for more than 30 days. Non-cytolytic L3T4+ T helper (Th) cells were capable of eliminating disseminated tumor without the participation of Lyt-2+ cytotoxic T cells (Tc). Purified or cloned Lyt-2+ T cells were also effective in therapy, but required the concurrent administration of either L3T4+ Th or interleukin 2 (IL-2) for optimal efficacy. L3T4+ Th appear to function via secretion of lymphokines that activate macrophages to a cytotoxic state. Lyt-2+ Tc, in addition to direct cytotoxicity, may mediate tumor eradication in part by secretion of lymphokines that activate in vivo tumoricidal macrophages. These studies suggested that the reported efficacy of individual T cell subsets in therapy of particular tumors might not reflect resistance or susceptibility to a cytotoxic effector mechanism, but rather the efficiency with which a T cell subset is activated by the tumor and/or recognizes the tumor antigen. Methods were developed to independently assess the activation and proliferation requirements of each subset. L3T4+ Th required that macrophages degrade tumor antigens in lysosomes and present the antigens in the context of class II molecules, and produced IL-2 and IL-4 as endogenous growth factors. By contrast, Lyt-2+ T cells recognized the tumor directly, required macrophages only to produce IL-1 for activation, and produced IL-2 but not IL-4 as an endogenous growth factor. The ability of T cell subsets to recognize the distinct retroviral tumor antigens expressed on FBL leukemia was assessed using cell lines or recombinant vaccinia viruses transfected with selected retroviral genes. Highly selective antigen recognition was detected, with Lyt-2+ Tc cells recognizing products of gag but not envelope genes, and L3T4+ Th recognizing envelope but not gag products. The results suggest that even complex unique tumor antigens may elicit only limited host T cell responses.
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PMID:Requirements for T cell recognition and elimination of retrovirally-transformed cells. 247 34

The Tax protein of human T-cell leukemia virus is a potent transcriptional activator of viral and cellular genes, including the genes for interleukin 2 and interleukin 2 receptor alpha chain (IL2R alpha). The NF-kappa B protein has been implicated in Tax-mediated activation of IL2R alpha gene expression. We show that activation of NF-kappa B by Tax is an indirect process that requires prior activation of a preexistent factor that is present in lymphoid cells. Deletion mutagenesis revealed that the carboxyl-terminal acidic region of Tax is required for activation of IL2R alpha-directed gene expression but dispensable for activation of the long terminal repeat (LTR). Our findings suggest that activation of viral and cellular gene expression by Tax is achieved through a cascade of events that involves multiple protein-protein associations and that the specificity of these associations is conferred through different domains of the Tax protein.
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PMID:Activation of NF-kappa B by the HTLV-I trans-activator protein Tax requires an additional factor present in lymphoid cells. 248 94

The granules of in vitro primed cytotoxic mouse T cells and cytotoxic cell lines have been shown to contain high levels of N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester (BLT) esterase. The enzyme activity has been suggested to be associated with the cytotoxic capacity of killer cells. We investigated human leucocytes and found that neutrophils, monocytes, cytotoxic T lymphocytes (CTL), natural killer (NK) cells [large granular lymphocytes (LGL)], and interleukin 2 activated killer (LAK) cells, which all display efficient cytotoxic capacity, show only marginal BLT esterase activity. The low BLT esterase activity in human lymphocytes increases about twofold when cells are stimulated in vitro with interleukin 2 (IL-2), phytohaemagglutinin (PHA), or cultured in mixed lymphocyte culture (MLC). Mouse T lymphocytes have about 20 times more BLT esterase activity than human T lymphocytes. The BLT activity in mouse T cells also increases about twofold in MLC. The human leukaemia cell lines (K562, U937, MOLT-4, Jurkat) and the mouse mastocytoma line (P815), which are frequently used as target cells, contain more BLT esterase activity than human resting or activated lymphocytes. We did not find a direct correlation between the cytotoxic capacity and the BLT esterase activity of killer cells.
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PMID:N-alpha-benzyloxycarbonyl-L-lysine thiobenzyl ester (BLT) serine esterase in human cytolytic effector cells and cell line targets. 252 94

The expression of transferrin receptors (TrfRs) was investigated in acute T-cell leukemia (T-ALL) blasts at the molecular, biochemical, immunological, and functional level. TrfRs, although not detected on quiescent T-cells from normal adults, are constitutively expressed at high level on the blasts from all T-ALL patients and bind normally to transferrin. Their number is modulated by the intracellular iron level, but is independent of exogenous interleukin 2. They also exhibit immunological and biochemical abnormalities, in that: (a) they react preferentially with monoclonal antibodies (MAb) that recognize ligand-binding domains of TrfR (42/6 and 43/31), as compared to MAbs (B3/25, OKT9) that interact with the nonligand binding domains; (b) they have a reduced molecular weight, as compared to TrfR on normal thymocytes and activated T-lymphocytes: this phenomenon is apparently related to a defective glycosylation. It is noteworthy that expression of TrfR was not observed in a large series of other types of acute leukemias, i.e., pre-B, B, and myeloid leukemias, excluding erythroleukemias. The constitutive, high level expression of TrfRs on T-ALL blasts may play a key role in the stepwise progression of this malignancy and particularly provide a proliferative advantage to T-ALL blasts as compared to normal T-lymphocytes. Furthermore, indirect evidence suggests that the glycosylation defect of TrfR on T-ALL blasts contributes to their tumorigenic capacity.
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PMID:Constitutive expression and abnormal glycosylation of transferrin receptor in acute T-cell leukemia. 258 41

We have established an interleukin 2-dependent, OKT4-positive T-cell line, named HCT-1, from cells in the cerebrospinal fluid obtained from a patient with human T-cell lymphotropic virus type I (HTLV-1)-associated myelopathy. Antigens for HTLV-I were detected in HCT-1 cells by indirect immunofluorescence and Western blot testing, and type C virus particles were detected by electron microscopy. Southern blot analysis of HCT-1 cellular DNA, using an HTLV-I probe, revealed that the integrated provirus genome could not be distinguished from the HTLV-I genome in adult patients with T-cell leukemia.
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PMID:Characterization of HTLV-I in a T-cell line established from a patient with myelopathy. 264 98

In a previous study, we reported that adult T-cell leukemia (ATL) cells produce interleukin 1 (IL1)-like factors that stimulate murine thymocyte proliferation, the production of interleukin 2 (IL2), and the expression of IL2 receptors (IL2R) on normal human T-cells in the presence of concanavalin A. In this communication, we studied the effect of IL1 on the growth of ATL cells in vitro. When ATL cells freshly obtained from patients were cultured with recombinant (r) human IL1 alpha, IL1 beta, or IL1-like factors produced by ATL cell lines, the growth of ATL cells was stimulated in a concentration-dependent manner. Maximum stimulation was observed at a concentration of 50-100 units/ml of IL1. The expression of IL2R on ATL cells was also enhanced by IL1, but the production of IL2 was not induced. These effects of rIL1 alpha or beta were specifically inhibited by anti-IL1 alpha or anti-IL1 beta antibody. Furthermore, the spontaneous growth of ATL cells was also inhibited by anti-IL1 alpha antibody, but not by anti-IL1 beta antibody. ATL cells exhibited enhanced expression of IL1 receptors on their surface as detected by the binding of 125I-labeled rIL1 alpha. These results suggest that IL1 alpha produced by ATL cells stimulates the growth of ATL cells by an autocrine mechanism.
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PMID:Autocrine stimulation of interleukin 1 alpha in the growth of adult human T-cell leukemia cells. 278 84

Malignant B cells, derived from hairy cell leukemia (HCL), non-Hodgkin's lymphoma (NHL) or prolymphocytic leukemia were stimulated with mitogens and interleukin 2 after careful depletion of contaminating T cells resulting in final residual percentages of less than 0.1. No proliferation was found as measured by 3H-thymidine incorporation. Subsequently, to the non-T B cell cultures very small amounts of autologous or allogeneic T cells were added, ending up in final concentrations of 0.1, 0.5, 1, or 2% T cells. It appeared that a marked proliferation occurred which had in various coculture combinations to be ascribed to the T cells alone. Moreover, most HCL and other B cell NHL additionally stimulated the T cells, resulting in a further increase in proliferation. We conclude that 3H-thymidine incorporation by malignant B cells such as HCL and B-NHL stimulated with mitogens and IL-2 will in most cases wrongly be attributed to proliferation by the B cells themselves, and instead has to be ascribed to contaminating T cells.
Leukemia 1989 Oct
PMID:Residual T lymphocytes, and not malignant B cells, proliferate upon mitogenic stimulation. 278 26

The early event of thymocyte maturation has been analyzed using acute lymphoblastic leukemia (ALL) cells. A group of ALL cells whose cell surface phenotype was CD2 (SRBC receptor) negative and CD7 (T cell antigen) positive has been considered as precursor thymocyte ALL (pre-T-ALL). No rearrangements of the T cell receptor beta-gene (TCR beta) and gamma-gene (TCR gamma) were found in three of four pre-T-ALL patients. Stimulation of these pre-T-ALL cells with 12-0-tetradecanoylphorbol-13-acetate (TPA) induced only CD25 (Tac) antigen but no other T cell antigens. These findings suggest that the activation pathway of interleukin 2 (IL-2) receptor already exists in the most immature precursor thymocytes. Pre-T-ALL cells from the fourth patients showed the expression of CD3 antigen, and both TCR beta and TCR gamma rearrangement. TPA induced the differentiation of the more mature pre-T-ALL cells of this case in vitro, and not only CD25 (Tac) antigen but also CD4 and CD8 antigens appeared on the cell surface. The low affinity binding of 125I-IL-2 to TPA-stimulated leukemia cells was observed in the three cases of pre-T-ALL tested, and the addition of recombinant IL-2 to TPA-stimulated cells showed no effect on cell proliferation.
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PMID:Phorbol ester induces interleukin-2 receptor on the cell surface of precursor thymocyte leukemia with no rearrangement of T cell receptor beta and gamma genes. 282 68

We examined the relationship of the leukemia-accelerating properties of a dual-tropic virus (DTV-70) (when injected into the thymus of 14-day-old AKR mice) to its ability to impair T cell functions. Splenic lymphocytes from virus-infected AKR mice were found to have reduced T cell mitogenic responses; moreover, these cells suppressed phytohemagglutinin stimulation of cells from normal, uninfected AKR mice. The response to the B cell mitogen lipopolysaccharide was slightly enhanced at 15 days following DTV-70 infection and was unaffected at later ages. AKR mice infected with DTV-70 showed reduced ability to develop delayed-type hypersensitivity reaction and interleukin 2 production. In contrast, spleen cells from the virus-infected mice responded normally to allogeneic stimulation in mixed lymphocyte culture and mounted an almost normal graft versus host reaction. The data suggest that DTV-70 impairs certain T cell functions that could interfere with immune surveillance and thus permit progression of preleukemic cells into overt leukemia. These T cell functions are suppressed normally by 6 months of age, perhaps by spontaneously arising DTV.
Leukemia 1987 May
PMID:Enhanced AKR leukemogenesis by the dual tropic viruses. II. Effect on cell-mediated immune responses. 282 21


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