Differential regulation of the two IL-2-binding proteins. Physiological consequences.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
F W Ruscetti
Publications and source records attributed to F W Ruscetti.
Retroviral v-myc infection of primary fetal liver cells: transformation of monocytes in vitro.
Oncogenes carried by retroviruses can alter the growth properties of many cell types. We examined the molecular mechanism by which a retrovirus containing one or a combination of oncogenes can transform and immortalize hematopoietic cells. Murine fetal liver cells were used as an enriched source of early hematopoietic cell progenitors; the cells were infected with a series of recombinant murine retroviruses capable of expressing the avian v-myc, v-H-ras and v-raf oncogenes. Three factor-independent cell lines were obtained: FL-ras/myc, FL-J2 (v-raf/v-myc) and FL-myc, a unique cell line generated using a single oncogene. Cytochemical, morphologic and phenotypic analyses indicated that these cell lines were of the monocyte lineage. Southern and Northern blot analyses revealed that the three cell lines had integrated viral DNA and were expressing the mRNA transcripts corresponding to these viral oncogenes. To examine the mechanism of factor independence, supernatants from these cell lines were tested for CSF-1 activity. Supernatants from FL-myc and FL-ras/myc cells were shown to contain CSF-1 activity and Northern blot analysis of the three cell lines revealed the presence of mRNA transcripts for the CSF-1 and c-fms genes. It is possible that the growth factor independence of these cell lines is related to the development of autocrine-induced proliferation.
Animals↗
Immature, double negative (CD4-,CD8-) rat thymocytes do not express IL-2 receptors.
IL-2R alpha-chain is expressed on a subset of mouse CD4- and CD8-, double negative (DN) thymocytes. This expression of IL-2R alpha-chain on some DN thymocytes in the mouse has led to the proposal that IL-2 might serve as a principal growth and/or differentiation factor for immature thymocytes. However, previous histologic observations have indicated that IL-2R alpha-chain is not expressed on the subcapsular thymic blasts (an area rich in DN cells) in either huma or rat thymus, whereas all three species display IL-2R expression on a few cells in the thymic medulla. Therefore, we characterized rat DN thymocytes to determine whether they contained an IL-2R+ population. The results show that rat thymic DN cells share several characteristics with mouse DN cells. However, most of the rat strains do not express the IL-2R on DN cells as shown either by immunofluorescence or by IL-2 binding and receptor cross-linking. Thus, the rare medullary IL-2R+ cells were not found in the DN cells. Only in the exceptional F344 rat strain is the IL-2R alpha-chain expressed on a major proportion of thymocytes, including both DN cells and small cortical-type thymocytes. Furthermore, rat DN cells do not contain detectable IL-2 mRNA or cytoplasmic IL-2 activity, thus supporting the conclusion that it is unlikely that IL-2 and IL-2R serve to maintain the proliferation of rat DN thymocytes in vivo. The possible significance of in vivo expression of IL-2R alpha-chain on immature thymocytes in the mouse and in a single rat strain is discussed.
Aging↗
Transforming growth factor beta 1 selectively regulates early murine hematopoietic progenitors and inhibits the growth of IL-3-dependent myeloid leukemia cell lines.
Transforming growth factor beta 1 (TGF-beta 1) has been shown to be associated with active centers of hematopoiesis and lymphopoiesis in the developing fetus. Therefore, the effects of TGF-beta 1 on mouse hematopoiesis were studied. TGF-beta 1 is a potent inhibitor of IL-3-induced bone marrow proliferation, but it does not inhibit the proliferation induced by granulocyte/macrophage, colony-stimulating factor (CSF), granulocyte CSF, and erythropoietin (Epo). TGF-beta 1 also inhibits IL-3-induced multipotential colony formation of bone marrow cells in soft agar, which includes early erythroid differentiation, while Epo-induced terminal differentiation is unaffected. In addition, IL-3-induced granulocyte/macrophage colonies were inhibited; however, small clusters of differentiated myeloid cells were consistently seen in cultures containing IL-3 and TGF-beta 1. Thus, TGF-beta 1 selectively inhibits early hematopoietic progenitor growth and differentiation but not more mature progenitors. TGF-beta 1 is also a potent inhibitor of IL-3-dependent and -independent myelomonocytic leukemic cell growth, while the more mature erythroid and macrophage leukemias are insensitive. Therefore, TGF-beta 1 functions as a selective regulator of differentiating normal hematopoietic cells, and suppresses myeloid leukemic cell growth.
Animals↗
Lectins modulate the internalization of recombinant interferon-alpha A and the induction of 2',5'-oligo(A) synthetase.
After binding to specific cell surface receptors, interferon-alpha (IFN-alpha) along with its receptor is internalized by the cells. However, the physiological significance of the internalization of IFN is not known. We have found that the lectin concanavalin A (ConA), which does not inhibit the binding of 125I-rIFN-alpha A, inhibits both the internalization of 125I-rIFN-alpha A and the rIFN-alpha A-induced increase in the levels of 2',5'-oligo(A) synthetase mRNA and enzymatic activity in the B lymphoblastoid cell line Daudi. The reduced level of IFN-induced 2',5'-oligo(A) synthetase in ConA-treated cells was due neither to direct inhibition of the enzymatic activity nor to generalized inhibition of protein or RNA synthesis. The dose-response curves were similar for the effect of ConA to inhibit 125I-rIFN-alpha A internalization and 2',5'-oligo(A) synthetase induction. The correlation between the ConA-mediated inhibition of both 125I-rIFN-alpha A internalization and 2',5'-oligo(A) synthetase induction suggests that internalization of rIFN-alpha A plays a role in the responses to rIFN-alpha A. However, since ConA inhibits protein mobility in the plasma membrane, it is possible that ConA is also preventing aggregation of IFN receptors or interactions between IFN receptors and signal transducing proteins in the plasma membrane that may be necessary for responses to IFN.
2',5'-Oligoadenylate Synthetase↗
Characterization of interleukin 2 and phorbol myristate acetate augmentation of expression of transfected human interferon-gamma genomic DNA.
We have reported that human interferon-gamma (IFN-gamma) genomic DNA is expressed after transfection into a mouse T-lymphoblastoid cell line and expression can be enhanced by both interleukin 2 (IL2) and phorbol myristate acetate (PMA). It can now be shown that PMA rapidly induces new transcription of the IFN-gamma gene and that increased human (Hu) IFN-gamma can be detected by 2 h after the addition of PMA to the mouse cells. Enhancement of IFN-gamma production by IL2 takes place with similar kinetics with increased IFN-gamma production observed at 4-6 h after IL2 addition, although the maximum amount of IFN-gamma produced in response to IL2 was significantly lower than that produced in response to PMA. Furthermore, along with increased levels of cytoplasmic IFN-gamma RNA, we were able to demonstrate increased nuclear transcription at 4 h after IL2 treatment. Stimulation of IFN-gamma mRNA by both PMA and IL2 could occur in the presence of cycloheximide, indicating that protein synthesis was not required for the initial stimulation to occur. However, the functional half-life of IFN-gamma mRNA after actinomycin D treatment was higher in cells that had been treated with PMA when compared with untreated or IL2-treated cells. This data indicates that there are quantitative differences in the ability of PMA or IL2 to augment IFN-gamma production, and that PMA may increase IFN-gamma production in the transfected cell by additional mechanisms, such as increasing mRNA stability.
Cell Division↗
Immunomodulation of neoplasia by interleukin 2.
Explore the source record for details and available documents.
Animals↗
Transforming growth factor beta selectively inhibits normal and leukemic human bone marrow cell growth in vitro.
The effects of transforming growth factor beta 1 or beta 2 (TGF-beta 1 or -beta 2) on the in vitro proliferation and differentiation of normal and malignant human hematopoietic cells were studied. Both forms of TGF-beta suppressed both the normal cellular proliferation and colony formation induced by recombinant human interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF). In the presence of GM-CSF or IL-3, optimal concentrations of TGF-beta (400 pmol/L) inhibited colony formation by erythroid (BFU-E), multipotential (CFU-GEMM), and granulocyte-macrophage (CFU-GM) progenitor cells by 90% to 100%, whereas granulocyte or monocyte cluster formation was not inhibited. In contrast, neither form of TGF-beta had any effect on G-CSF-induced hematopoiesis. The suppressive action appeared to be mediated directly by TGF-beta since antiproliferative responses were also observed in accessory cell-depleted bone marrow cells. In contrast to normal bone marrow cells, both GM- and G-CSF-induced proliferation of cells from patients with chronic myelogenous leukemia were suppressed in a dose-dependent manner by TGF-beta. Differential effects of TGF-beta on the proliferation of established leukemic lines were also observed since most cell lines of myelomonocytic nature studied were strongly inhibited where erythroid cell lines were either insensitive or poorly inhibited by TGF-beta. These results suggest that TGF-beta is an important modulator of human hematopoiesis that selectively regulates the growth of less mature hematopoietic cell populations with a high proliferative capacity as opposed to more differentiated cells, which are not affected by TGF-beta.
Antigen-Antibody Reactions↗
Interleukin 2 receptor: two distinct proteins bind interleukin 2.
Explore the source record for details and available documents.
Antigens, Surface↗
Similar rearrangements of T-cell receptor beta gene in cell lines and uncultured cells from patients with large granular lymphocyte leukemia.
We established interleukin-2-(IL-2) dependent cell lines from three patients with large granular lymphocyte (LGL) leukemia. Phenotypic analysis demonstrated retention of the CD3+, CD8+ phenotype that was observed in the original leukemic LGL. Unique rearrangements of T-cell receptor beta gene occurring in uncultured leukemic LGL, were also found in cell lines, which suggests that the cell lines were derived from the original leukemic LGL clone in each case.
Antigens, Surface↗
Trophoblast cell line conditioned medium for in vitro culture and antigenic characterization of acute myeloid leukemia clonogenic cells.
The colony-stimulating factor-containing supernatant of the human trophoblast cell line TPA-30-1 was used to stimulate in vitro growth of acute myeloid leukemia clonogenic cells from 54 patients. Prevalent colony growth (10-greater than 1000) was observed in 63% of cases. In 31% clusters and a few colonies (1-9/1 x 10(5) plated cells) were scored. Neither colonies nor clusters could be detected in the remaining 6%. The best growth was observed in subtype M5 (8 of 9 cases, 89%). Morphological examination and recloning tests suggested that the colonies originated from leukemic progenitors. TPA-30-1 supernatant stimulation can therefore be compared with that of phytohemagglutinin or phytohemagglutinin-leukocyte-conditioned medium. In addition it does not require T-lymphocyte removal and batch screening. Extension of the culture for antigenic characterization of acute myeloid leukemia clonogenic cells to more patients than in a previous study confirmed the existence of a subgroup (39%) of patients whose acute myeloid leukemia clonogenic cells constantly expressed late myeloid differentiation antigens recognized by the monoclonal antibody S4-7. Since S4-7 spares early normal hemopoietic progenitors, this subgroup (54% M2) can be considered as candidates for autologous bone marrow transplantation after in vitro purging with S4-7 monoclonal antibody and complement.
Antigens, Neoplasm↗
Interleukin 2 rapidly stimulates synthesis and breakdown of polyphosphoinositides in interleukin 2-dependent, murine T-cell lines.
Several T-cell functions are controlled by the regulatory peptide interleukin 2 (IL-2). Binding of IL-2 with specific receptors has been well documented, but the molecular mechanism by which IL-2/IL-2 receptor interaction is transduced is not known. We have found that treatment of IL-2-dependent T-cell lines with IL-2 is followed by a rapid stimulation of inositol phospholipid metabolism, as determined by isotopic methodology employing myo-[1,2-3H]inositol. Increased incorporation of the metabolic precursor into phosphatidylinositol and phosphatidylinositol 4-monophosphate, together with the appearance of radiolabeled phosphatidylinositol 4,5-bisphosphate, occurred within minutes of treatment with IL-2 of factor-dependent CT6 cells. Analysis of labeled water-soluble compounds from prelabeled cells indicated a rapid (within 1 min) stimulation of inositol phospholipid hydrolysis following IL-2 treatment. Increased recovery of [3H] inositol phosphates and appearance of [3H]inositol trisphosphate were observed after treatment with IL-2 of CT6 cells, as well as of a second IL-2-dependent cell line, CTB6. These findings suggests that inositol phospholipid-derived metabolites (i.e. diacylglycerol and inositol trisphosphate) may be part of the mechanism by which certain IL-2 signals are transduced.
Animals↗
Serum reactivity to human T-cell leukaemia/lymphoma virus type I proteins in patients with large granular lymphocytic leukaemia.
To investigate the possibility that the recently recognised syndrome, leukaemia of large granular lymphocytes, could be associated with human T-cell leukaemia/lymphoma virus type I (HTLV-I), sera from 12 patients with this type of leukaemia were tested by the use of western-blot techniques for IgG antibodies to proteins related to human T-cell leukaemia/lymphoma virus type I (HTLV-I). Sera from 6 patients, including 2 patients with rheumatoid arthritis, reacted with p19 or p24 retroviral proteins or both. In contrast, no sample from 32 patients with uncomplicated rheumatoid arthritis, 27 with Felty's syndrome, 11 with other connective tissue disorders, or 21 normal individuals reacted with HTLV-I. The results suggest that leukaemia of large granular lymphocytes may be associated with a retrovirus related to HTLV-I.
Adult↗
Regulation of human large granular lymphocyte and T cell growth and function by recombinant interleukin 2: induction of interleukin 2 receptor and promotion of growth of cells with enhanced cytotoxicity.
Human large granular lymphocytes (LGL), which account for virtually all natural killer activity, and T cells were separated from low and high density fractions of Percoll gradients, respectively. We were unable to detect interleukin 2 receptors (IL 2R) on fresh LGL and T cells using flow cytometric analysis with anti-Tac monoclonal antibody or radiolabeled probes with [125I]anti-Tac. IL 2R messenger ribonucleic acid was not observed in fresh LGL or T cells. Although phytohemagglutinin induced the expression of IL 2R on purified LGL and T cells, recombinant IL 2 (rIL 2) alone induced IL 2R messenger ribonucleic acid, IL 2R, and proliferation of LGL but not of T cells. The high level of cytotoxicity of cultured LGL against K562 cells was directly dependent on rIL 2. When T cells were costimulated by phytohemagglutinin and rIL 2 for 3 days, only very low levels of cytotoxicity were generated. Proliferation and cytotoxicity against K562 cells inhibited the culture of LGL in the presence of anti-Tac antibody for 3 days. LGL began to grow more rapidly after 5 days in culture with rIL 2 alone. When rIL 2 were removed from growing LGL for 1 day, proliferation completely stopped, and cytotoxicity was no longer detected. These data indicate that rIL 2 induces IL 2R expression in fresh LGL at the transcriptional level, promoting growth and enhancing cytotoxicity. More importantly, the presence of rIL 2 is necessary and sufficient to induce proliferation of resting LGL and to maintain the growth of LGL with potent lytic activity.
Cell Division↗
Regulation of expression of the interleukin-2 receptor on hematopoietic cells by interleukin-3.
Remarkable similarities in the intracellular and genetic events occur when lymphoid and hematopoietic cells are exposed to their specific growth factors. The interleukin-2 (IL-2) receptor, whose cell-surface expression is an absolute requirement for the growth and differentiation of lymphoid cells, was detected on various nonlymphoid hematopoietic cell types in this study. Cell lines consisting either of granulocyte-macrophage precursors or mast cells, which are dependent on interleukin-3 (IL-3) for their growth, expressed high levels of the IL-2 receptor on their surface. Analysis of the binding characteristics of these receptors with 125I-labeled recombinant IL-2 revealed that only receptors with low affinity for IL-2 were present on these cells. Addition of purified recombinant IL-3 to these cell lines led to an increase in IL-2 receptor gene expression within 1 hour in isolated nuclei. This IL-3--induced increase in the number of IL-2 receptors on the cell surface is maximal within 24 hours. Addition of 10,000 units of IL-2 to these cells had no apparent effect on their growth or differentiation. The presence of the receptor with only low affinity for IL-2 on hematopoietic cells and the regulation by IL-3 suggest that this receptor is involved in some important metabolic event in hematopoiesis.
Animals↗
Establishment of a human B cell line that proliferates in response to B cell growth factor.
A human B cell line which shows a marked dose dependence on B cell growth factor (BCGF) when cultured in less than or equal to 2% serum has been established. Human B lymphocytes were obtained from peripheral blood of normal donors and cultured in the presence of anti-IgM (mu chain specific) and BCGF. Frequent refeedings with fresh medium containing BCGF and anti-IgM led to the establishment of a long term cultured human B cell line, HAB-40. Phenotyping of HAB-40 revealed that the cell population consisted predominantly of IgM-bearing (72%) and B1 (100%) positive cells. This B cell line consistently secreted IgM and IgG when co-cultured in the presence of PMA, anti-IgM and beta or gamma interferon (IFN). Also, it was Epstein-Barr virus nuclear antigen (EBNA) positive (100%). HAB-40 cells have been successfully maintained in the presence of BCGF without anti-IgM for over a year. Removal of BCGF led to the rapid loss of viable cells in cultures containing less than 2% serum. HAB-40 cells in microassays exhibited a marked dose-dependent incorporation of [3H]thymidine in response to BCGF in the absence of any exogenous stimulants such as anti-IgM or Staphylococcus aureus Cowan I (SAC). Recombinant interleukin 2 (IL-2) failed to augment the [3H]thymidine uptake by these B cells despite the low density expression of Tac antigen (IL-2 receptor) on their cell surface, or even when the cells were stimulated with phorbol myristate acetate (PMA) to express higher density of Tac antigen (48%). HAB-40 cells could be maintained in BCGF which was partially purified to deplete it of other contaminating proteins. None of the seven well established EBNA-positive human B cell lines nor two chronic B lymphocytic leukemia (B-CLL) cell lines that were tested showed BCGF dependence. The same BCGF-active chromatographic fractions that were active on HAB-40 cells also stimulated BCL1 and normal human B cells stimulated with anti-IgM. In the presence of less than or equal to 2% serum proteins this cell line provides a simple, reproducible assay for BCGF even in the presence of contaminant IL-2.
Antibodies, Anti-Idiotypic↗
Analysis of effector mechanisms against HTLV-I- and HTLV-III/LAV-infected lymphoid cells.
Acquired immunodeficiency syndrome is associated with a viral (HTLV-III/LAV)-mediated progressive depletion of a helper/inducer T4+ T cell subset, whereas acute T cell leukemia is associated with a viral (HTLV-I)-mediated growth of the same T cell subset. Because large granular lymphocytes (LGL) with natural killer (NK) activity have been shown to spontaneously lyse several virus-infected target cells, the ability of NK cells to lyse both HTLV-I- and HTLV-III/LAV-infected lymphoid cell lines and fresh lymphocytes was explored. Normal lymphocytes (T cells and LGL), with and without pretreatment with recombinant interleukin 2 (IL 2), as well as monocytes, with and without pretreatment with interferon-gamma were employed as effectors. Both IL 2-activated T cells and NK cells were cytolytic for HTLV-I-infected targets. However, only LGL demonstrated significant spontaneous activity against HTLV-I-infected targets. Similarly, LGL showed spontaneous cytolytic activity against HTLV-III/LAV-infected targets, and this cytotoxicity was considerably augmented by IL 2. In contrast, T cells and monocytes were unable to lyse HTLV-III/LAV targets, and only minimal activity was induced by activation. LGL cells, B cells, and monocytes were infectible in vitro by high titers of HTLV-III/LAV. However, levels of reverse transcriptase found in these cultures were significantly lower than the levels in T cell cultures. In contrast, only T cells were susceptible to infection by HTLV-I. Experiments with the use of cell cocultures showed that LGL afforded T cells protection from infection by HTLV-I (as indicated by lack of transformation and viral protein expression) but not from infection by HTLV-III/LAV. Collectively, these results indicate that NK cells may play a role in protecting cells against HTLV infection.
Acquired Immunodeficiency Syndrome↗
Association of protein kinase C activation with IL 2 receptor expression.
Tac antigen (as a measure of the IL 2 receptor) acquisition and regulation by IL 2, an antigen-receptor agonist (anti-T3), phorbol esters, and phytohemagglutinin (PHA) were studied. Phorbol esters stimulated de novo acquisition of Tac antigen, which was associated with the subcellular redistribution of protein kinase C (PK-C) from cytosol to particulate membranes of human T lymphocytes. PHA and anti-T3 (alpha-T3) antibody also stimulated a transient redistribution and activation of PK-C that reached a maximum within 20 min after stimulation. Both phorbol esters and alpha-T3 could increase Tac expression and stimulate PK-C translocation on 5 and 12 day activated T cells that were at the G0/G1 stage of the cell cycle due to IL 2 deprivation. Tac antigen-specific mRNA was seen in the nucleus within 2 hr after stimulation. In contrast, IL 2 alone could only increase Tac expression and stimulate PK-C translocation on day 5 but not day 12 activated T cells. IL 2 synergizes with alpha-T3 and phorbol ester for the regulation of Tac expression. Although IL 2 increased expression of Tac, the majority if not all of these receptors possessed low affinity for IL 2. These data suggest that the activation of PK-C is a common transmembrane signal shared by IL 2 and antigen stimulation. The results also imply that PK-C activation is necessary for the regulation of Tac antigen expression.
Adult↗