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Biomedical subjects

F W Ruscetti

Publications and source records attributed to F W Ruscetti.

At least 163 records · Page 9Linked to original sources
PubMed1986

Identification and characterization of a human T cell line-derived lymphokine with MAF-like activity distinct from interferon-gamma.

Culture supernatants of several human T cell leukemia cell lines were screened for macrophage-activating activity (MAF) as defined by induction of tumoricidal activity against human melanoma cells in a 72-hr assay. Two cell lines, MT-2 and C10/MJ2, were found to produce high levels of MAF activity constitutively, but the MT-2 cell line, unlike C10/MJ2, produced little IFN-gamma. This observation was confirmed by Northern blot analysis performed with specific IFN-gamma cDNA probe. The MT-2 cell line thus provides a useful system to evaluate the existence of lymphokines with MAF activity that are distinct from IFN-gamma. The MAF activity produced by MT-2 cells was distinguished from IFN-gamma by the following criteria. MAF activity was not removed by immunoaffinity chromatography with the use of immobilized specific polyclonal antibodies to IFN-gamma and was not neutralized by a monoclonal antibody to IFN-gamma. Heat or acid treatments of IFN-gamma resulted in loss of its antiviral activity, but these treatments had no effect on MAF activity. MAF activity was not abolished by polymyxin B sulfate, suggesting that this activity is not mediated by or dependent on LPS. Initial characterization studies performed by using membrane filtration, gel filtration chromatography, and isoelectric focusing indicate that the non-IFN-gamma MAF activity produced by MT-2 cells has an apparent m.w. of 55,000 and an isoelectric point of 5.5. Collectively, these data suggest that the MT-2 human T cell line constitutively produces high levels of MAF and low levels of IFN-gamma and offers a useful source for the further purification of a unique human lymphokine with macrophage-activating activity that is distinct from IFN-gamma.

Cell Line↗
PubMed1986

Modulation of E-receptor expression on activated T lymphocytes.

Our study indicated that the newly synthesized E-receptor, as measured with 125I-labeled monoclonal anti-E receptor antibody, on activated T lymphocytes were responsible for forming stable E-rosettes at 37 degrees C. Maximum induction of new E-receptor expression required at least 50 hr of culture with polyclonal T-cell activators, phytohemagglutinin, or phorbol myristate acetate. Polyclonal B-cell activator, lipopolysaccharide were not able to induce new E-receptor expression on the surface of T lymphocytes. The expression of the new E-receptor paralleled with the induction of Tac antigen expression. Interleukins 1 and 2 or Interferon-gamma were not able to initiate the induction of new E-receptors. However, a neuropeptide, endorphin exhibited biphasic effect on modulating the E-receptor expression, in the absence of polyclonal activators. As is the case with Tac antigen expression, induction of new E-receptor antigen may be a marker for activated T lymphocytes.

Animals↗
PubMed1986

Octapeptides deduced from the neuropeptide receptor-like pattern of antigen T4 in brain potently inhibit human immunodeficiency virus receptor binding and T-cell infectivity.

The differentiation antigen T4, present on the helper/inducer subset of T lymphocytes, is thought to serve as the receptor for the human immunodeficiency virus (HIV). We find that a 60-kDa protein, immunoprecipitable by monoclonal antibody (mAb) OKT4, is present on membranes from human brain as well as human T cells. Furthermore, the radioiodinated HIV envelope glycoprotein [125I-labeled gp120 (125I-gp120)] can be specifically covalently affixed to a molecule present on rat, monkey, and human brain membranes to yield a complex that is indistinguishable from that formed on human T cells. T4 antigen has been studied on unfixed squirrel monkey, rat, and human brain sections by autoradiography using the mAb OKT4. A highly conserved neuroanatomical pattern has been demonstrated, suggesting an analogous organization in these three mammalian brains. Furthermore, the localization of 125I-gp120 receptor binding appears similar to that of T4 and is highly reminiscent of patterns for many previously characterized neuropeptide receptors. A computer-assisted analysis of gp120 suggested that a previously unremarkable octapeptide sequence within the gp120 protein, which we have synthesized and termed "peptide T," may play an important role in HIV attachment. Thus, peptide T and three rationally designed peptide analogs, each with a systematic amino acid substitution, potently inhibit specific 125I-gp120 binding to brain membranes. Additionally, when tested in a viral infectivity assay, these peptides show the same rank order and similar absolute potency to block HIV infection of human T cells. Thus, peptide T may provide a useful pharmacological or immunological basis for the control and treatment of AIDS.

Amino Acid Sequence↗
PubMed1986

Relationship of the clinical response and binding of recombinant interferon alpha in patients with lymphoproliferative diseases.

Patients with hairy cell leukemia (HCL) and chronic lymphocytic leukemia (CLL) were treated with recombinant interferon alpha A (rIFN-alpha A). The binding of iodinated recombinant interferon-alpha to baseline samples of peripheral blood mononuclear cells (PBMCs) from the leukemia patients was compared with clinical responsiveness to rIFN-alpha A. HCL patients (8/10) responded to rIFN-alpha A therapy, whereas none (0/10) of the CLL patients studied responded. The PBMCs from the eight responsive HCL patients bound approximately twice as much iodinated interferon as the PBMCs from nonresponsive CLL patients. This difference was due to more high-affinity receptors per cell with no difference in the affinity of the interferon-receptor interaction. However, because PBMCs from HCL patients were larger than PBMCs from CLL patients, the cell surface receptor density was similar. The leukemic cells from one of the two nonresponsive HCL patients bound iodinated interferon similarly to the cells from the responsive HCL patients, whereas the leukemic cells from the other nonresponsive HCL patient bound considerably less. The rapidity of response of the HCL patients did not correlate with the level of binding of iodinated interferon. Our results suggest that the absolute number of interferon receptors per cell may be only one of several important parameters in the response to rIFN-alpha A therapy, and that the responsiveness of a particular lymphoproliferative disease or a particular patient to rIFN-alpha A therapy cannot be predicted or explained solely by the degree of interaction between IFN and its cell surface receptor.

Cell Separation↗
PubMed1986

Ligand-specific calcium mobilization in IL 2 and IL 3 dependent cell lines.

Calcium mobilization is one of the earliest quantitative biochemical events associated with extracellular messenger stimulation of cellular proliferation. Therefore, purified recombinant lymphokines Interleukin 2 (IL 2) and Interleukin 3 (IL 3) were examined for ligand stimulation of calcium mobilization with highly specific interleukin-dependent cloned cell lines. Although IL 2 and IL 3 share neither amino acid structural homologies nor cellular tissue specificity, both recombinant polypeptides induced rapid influx of calcium into quiescent cells bearing specific receptors for the ligand. Neither ligand was capable of stimulating calcium mobilization in the non-homologous target cells which differed in tissue lineage. Stimulation of calcium mobilization demonstrated characteristic threshold dose-response kinetics and was observed under conditions where intracytoplasmic calcium levels were spontaneously depleted upon ligand deprivation. These data confirm that in addition to the activation of protein kinase C, growth regulatory polypeptides of mature T lymphocytes (IL 2) and hematopoietic stem cells (IL 3) share common biochemical features of the ligand-receptor signal transduction apparatus which initiates cellular proliferation.

Animals↗
PubMed1986

In vivo induction of terminal differentiation of malignant myelopoietic progenitor cells by CSF-inducing biological response modifiers.

We have investigated the mechanisms by which colony-stimulating factor (CSF)-inducing biological response modifiers (BRM) may have beneficial effects on tumor-bearing hosts undergoing anti-tumor therapy. First, we have documented that treatment of mice with the chemically defined BRM maleic anhydride divinyl ether copolymer (MVE-2), which induces CSF secretion by macrophages (M phi) and bone marrow cells (BMC), significantly increased growth and differentiation of normal myelopoietic cells and counteracted the myelosuppressive effects of cyclophosphamide (CY). Second, we established that MVE-2 may exert CSF-mediated antitumor effects on certain leukemic tumor cells. Serum from mice pretreated in vivo with MVE-2, which contained CSF, induced terminal differentiation of cloned tumor cells from the CSF responsive WEHI-3B D+ subline in vitro, but not from the WEHI-3B D- subline, which is unresponsive to CSF. In vivo experiments showed that treatment of mice bearing the WEHI-3B D+ tumor first with CY and three days later with the CSF inducer MVE-2, significantly increased their survival time and rendered 20% to 50% of the tumor-bearing mice disease free. No such effects were obtained in mice bearing the WEHI-3B D- tumor. Thus, the induction of CSF or other differentiation factors by some BRMs may result in therapeutic effects against certain leukemias based on at least two distinct mechanisms: In addition to their restorative effects on normal bone marrow functions, CSF-inducing BRMs may also prevent further leukemogenesis by induction of terminal differentiation of leukemic cells.

Animals↗
PubMed1986

Comparative evaluation of multiple lymphoid and recombinant human interleukin-2 preparations.

Six lymphoid human interleukin-2s (nIL-2s) [four from peripheral blood mononuclear cells (PBMC) and two from JURKAT cells] and six recombinant IL-2s (rIL-2s) were obtained for comparative evaluation. The main issues addressed were possible differences among the preparations in potency in T cell growth assays and other functional assays, and the possible presence of other cytokine activities or contaminants. Each preparation was assigned a standardized IL-2 activity in reference units (RU) by comparing its T cell growth promoting activity against the Biological Response Modifiers Program IL-2 (JURKAT) reference reagent. Relative to the IL-2 unitage indicated by the suppliers, the RU varied from 110-fold less to 38.5-fold more for the various preparations. Two nIL-2s and two rIL-2s contained significant levels of endotoxin. One nIL-2 contained low levels of both alpha and gamma interferon (IFN), and one nIL-2 had a high level of gamma IFN. All other IL-2s were negative for IFN activity. All IL-2 preparations significantly augmented human natural killer (NK) activity, although the amount of RU required varied from 0.1 to 50 RU. Four nIL-2s and three rIL-2s induced human PBMC to produce gamma IFN, whereas two nIL-2s and one rIL2 did not. All nIL-2s had substantial amounts of B cell growth factor activity, whereas none of the rIL-2s consistently displayed this activity. All IL-2s stimulated the tritiated thymidine [3H]TdR incorporation of human PBMC in the absence of other stimuli, in addition to augmenting the response to mitogen or alloantigens. Some nILs and IL-2s had effects on human monocytes such as inhibiting migration, inducing cytotoxic or growth inhibitory activity against tumor cells, and causing changes in cell surface markers. The IL-2s were also tested for activity in vitro and in vivo in mice. Although there was a 12-fold variation in activity among the preparations, all but one of the IL-2s showed augmentation of the mixed lymphocyte reaction activity and all IL-2s tested stimulated macrophage cytotoxicity in vitro. All IL-2s tested enhanced the mixed lymphocyte-allogeneic tumor cell reaction resulting in greater production of cytotoxic T cells. However, significant quantitative differences in potency were evident among the various IL-2 preparations, especially the nIL-2s. Only very high doses of IL-2 (intraperitoneal injection of 100,000 RU/animal) induced in vivo augmentation of splenic or peritoneal NK cells, although all IL-2s tested increased NK activity against tumor target cells in vitro with substantially lower doses (10-100 RU/ml).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Modulation of interleukin 2 release from a primate lymphoid cell line in serum-free and serum-containing media.

The ability to grow a clone of the cell line, MLA144, which is a constitutive producer of interleukin 2 (IL-2), in serum-free medium permitted the study of the direct effect of various agents on cell growth and IL-2 production in a homogeneous population. Bovine serum albumin (BSA) at 4 mg/ml was optimal for cell growth and IL-2 production. Selenium at 10 ng/ml enhanced IL-2 production nearly twofold and lithium at 42 ng/ml also enhanced IL-2 production by nearly twofold. Neither compound at these levels altered cellular proliferation. Two other compounds, iron and zinc, known to be associated with cellular proliferation and/or immunoregulation did not alter IL-2 production. Catalase or horseradish peroxidase was able to substitute for BSA and maintain the long-term growth of the MLA144 clone with only a 30% decrease in the rate of cellular proliferation and a 50% decrease in IL-2 production compared to cells maintained in the serum-free formulation with BSA. Addition of 0.5 mg of BSA to the catalase serum-free formulation increased the production of IL-2 to 70% of that of cells cultured in the BSA-containing serum-free formulation. The catalase-containing serum-free formulation has the advantage of consisting of only three proteins, catalase, insulin, and transferrin, at a very low protein content. The catalase-containing serum-free medium also supported the long-term growth of a human T-cell line, HSB-2.

Animals↗
PubMed1985

The generation of stable human T-cell hybridomas which constitutively produce interleukin-2 and chemotactic factor.

We report the successful generation of human T-cell hybridomas that constitutively secrete lymphokines. An acute lymphoblastic leukemia T-cell line, CCRF-H-SB2, free of reverse transcriptase and mycoplasma, was sensitized to hypoxanthine, aminopterin, and thymidine (HAT) by selecting out a mutant deficient in hypoxanthine guanine phosphoribosyl transferase (HGPRT) in 8-azaguanine. Peripheral blood T lymphocytes from normal donors were incubated in vitro with 10 micrograms/ml of concanavalin A for 48 h and subsequently fused with the CCRF-H-SB2 HAT-sensitive cell line. Following 5 weeks in culture, 38 of 440 wells (8.6%) demonstrated hybridoma growth. Supernatants of these cultures were screened for interleukin-2 (IL-2), chemotactic factor, interferon, migration inhibition factor, and macrophage-activating factor activities. Twelve (of 38) hybrids exhibited IL-2 activity, and eight of these were successfully cloned. The highest secreting clone was demonstrated to have mRNA to IL-2 while the parent CCRF-H-SB2 had no detectable mRNA to IL-2. Three hybrid cultures produced chemotactic factor; one was successfully cloned and grown in serum-free medium, where it continued to constitutively produce chemotactic factor as well as IL-2 activity. The chemotactic factor was determined to have the same molecular weight (12,500 daltons) as leukocyte-derived chemotactic factor. Constitutive IL-2 production remained stable for over 12 months. None of the hybridomas tested produced detectable levels of gamma interferon, migration inhibition factor, or macrophage activation factor. Because these T-cell hybridomas produce lymphokines constitutively and this phenotype is stable, they can be an important source of highly purified human lymphokines for clinical and laboratory investigations.

Antigens, Surface↗
PubMed1985

Immunopathology associated with human lymphotropic retroviruses.

The human lymphocytotropic retroviruses, despite the fact that their immunopathology varies from acute immunodeficiency to leukemia, have several features in common: they are exogenous viruses isolated from mature T cells, especially T4+ T-cells; they preferentially infect mature T4+ T cells in vitro, although other kinds of cells can be infected (no pathologic effects have been associated with infection of nonlymphoid cells); they possess a reverse transcriptase with similar size and preference for Mg++; they have a unique pX sequence in their genome which codes for a protein which is responsible for trans-activation of viral and possibly cellular genes, and in vitro infection of some T cells induces either continuous proliferation or cytotoxicity which mimic the in vivo manifestations of the virus.

Acquired Immunodeficiency Syndrome↗
PubMed1985

T cell growth factor required for optimal induction of T cell growth factor receptor expression in phytohemagglutinin-stimulated T cells.

Proliferation of normal human T cells in vitro requires activation of resting T cells by lectin or antigen. This stimulation initiates a series of events which includes elaboration of T cell growth factor (TCGF), expression of TCGF receptors, and, ultimately, cellular proliferation. We sought to determine if TCGF was required for expression of the TCGF receptor in phytohemagglutinin (PHA)-stimulated normal human T cells. Utilizing dexamethasone (DEX), a known inhibitor of TCGF production, reductions in T cell proliferation, TCGF production, and TCGF receptor expression, as measured by TCGF adsorption and Tac acquisition, were demonstrated after PHA stimulation. When exogenous partially purified TCGF was added to DEX-containing cultures, the DEX inhibition of proliferation and TCGF receptor expression was completely reversed. These experiments were reproduced utilizing both highly purified TCGF from the Jurkat cell line and purified TCGF synthesized by bacteria from cloned TCGF DNA. Short-term experiments showed TCGF to be capable of restoring Tac antigen expression after DEX inhibition in the absence of cellular proliferation. These results indicate that TCGF is required for optimal expression of Tac antigen-associated TCGF receptors in PHA-activated T cells.

Antigens, Surface↗
PubMed1985

Characterization of factor-producing and factor-dependent clones from long-term hamster bone marrow suspension cultures.

Long-term hamster bone marrow (BM) cultures produce stem cells that can be grown in the absence of an adherent layer and without addition of exogenous growth factors or hormones. Cloning of these three- to five-month-old suspension cultures by the limiting dilution method generated both factor-dependent (FD) and factor-producing (FP) cell lines. The FP clones have been in culture for two years and are composed of macrophages by morphologic and histochemical criteria. FP serum-free conditioned medium (FPCM) produces both stimulatory and inhibitory effects on hematopoiesis. Addition of 1%-5% FPCM to fresh or cultured hamster BM cells stimulates both CFU-C and erythropoietin (epo)-dependent BFU-E colony formation but not CFU-GEMM in semisolid media, as well as increased numbers of differentiating myeloid and erythroid cells in suspension. In contrast, addition of 10%-15% FPCM produces substantial inhibition of epo-stimulated erythropoiesis. FD cells have been in culture for over 12 months. They exhibit an absolute requirement for the continued presence of 5% hamster spleen conditioned medium (SCM). The clones generate varying numbers of "blast" cells, myeloid and macrophage elements, and occasional mastlike cells. Addition of increasing amounts of SCM produces a dose-dependent proliferation and differentiation of FD cells and also stimulates CFU-C but not BFU-E or CFU-GEMM colony formation. FD cells will also respond to FPCM, but concomitant addition of SCM and FPCM generates four times more cells than either CM alone. These results suggest that the hamster suspension cultures contain both stem cells and distinct regulatory cells that stimulate the growth and differentiation of myelopoiesis.

Animals↗
PubMed1985

Regulation of erythropoiesis in long-term hamster marrow cultures: role of bone marrow-adherent cells.

The initial establishment of hamster long-term bone marrow (LTBM) cultures requires formation of an adherent stromal layer, but continued long-term proliferation of these cultures is best accomplished by removal of the suspension cells from the adherent layer and subsequent incubation in liquid suspension culture. Continued maintenance of bone marrow cells in the presence of the adherent layer for more than four to six weeks leads to a decline and eventual disappearance of erythroid and multipotent colony-forming cells. Addition of erythropoietin to LTBM suspension cultures produces mature, hemoglobinized erythrocytes. Incubation of the same cells plus erythropoietin in the presence of autologous parental adherent layers markedly inhibits both terminal erythroid differentiation and the number of detectable erythroid burst-forming units (BFU-Es). This erythroid inhibition occurs primarily within the first 24 hours with little or no effect on CFU-GEMMs or granulocyte-macrophage colony-forming units (GM-CFUs). However, continued incubation for seven days produces a reduction in all parameters. Removal of suspension cells from the adherent layer and restimulation with erythropoietin allows regeneration of erythropoiesis. Pretreatment of suspension cells with erythropoietin for 96 hours before exposure to the adherent culture only slightly inhibits erythropoiesis, suggesting that more mature erythroid progenitors are unaffected. Conditioned medium from the marrow adherent layer (ALCM) produces similar erythroid inhibitory effects in LTBM cultures with as little as two hours of incubation. The inhibition is actively produced by the adherent cells, since cycloheximide abolishes its production, while indomethacin has no apparent effect. Adherent marrow stromal cells may regulate hemopoiesis through negative as well as positive humoral signals, and they are particularly effective in erythroid regulation.

Alprostadil↗
PubMed1984

Functional diversity within the suppressor phenotype as defined by monoclonal antibody in T-cell prolymphocytic leukemia.

A patient with T-cell prolymphocytic leukemia (T-PLL) is described. The malignant T-cells from the patient were predominantly Leu-2-positive, indicating a suppressor phenotype. The cells were then tested to determine their functional capabilities. The patient's Leu-2-positive cells initially suppressed B-cell proliferation, as predicted by their phenotype but later functioned as T helper cells in the pokeweed mitogen system without a change in phenotype. The cells also responded inadequately to alloantigen and mitogen despite addition of exogenous T-cell growth factor (TCGF). Leu-2-positive prolymphocytes from the spleen of the patient were constitutive producers of TCGF. Surface phenotype using monoclonal antibody was inadequate to predict T-cell function of the cells from this patient with T-PLL. In addition, these data suggest there may be functional subpopulations within the OKT8+ phenotype. Constitutive TCGF production by malignant post-thymic T-cells may represent a mechanism by which these cells sustain their own growth.

Antibodies, Monoclonal↗