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R Munker

Publications and source records attributed to R Munker.

At least 73 records · Page 4Linked to original sources
PubMed1987

Tumor necrosis factor: receptors on hematopoietic cells.

Tumor necrosis factor (TNF) is a monokine that is cytotoxic/cytostatic for a variety of tumor cells and has multiple effects on normal cells. We demonstrate that normal and malignant human myeloid cells express a single class of high-affinity receptors (400 to 1,900 per cell, KD 20 to 90 pmol/L) for TNF. Mitogen-stimulated lymphocytes have a similar number of TNF receptors, whereas resting lymphoid cells have fewer receptors. RBCs and platelets have no detectable TNF receptors. No correlation is observed between the receptor number, receptor affinity, and the cytotoxic effect of TNF on myeloid cell lines. Significant cytotoxic effects of TNF on the most sensitive myeloid cell line (HL-60 promyelocytes) could be seen at concentrations tenfold lower than those concentrations at which one half of the TNF receptors were occupied. Our data show that significant biologic effects of TNF can occur at low levels of receptor occupancy and resistance to TNF is not related to the absence of TNF receptors on certain myeloid leukemic cell lines.

Blood Cells↗
PubMed1987

In vitro interaction of recombinant tumor necrosis factor alpha and all-trans-retinoic acid with normal and leukemic hematopoietic cells.

Both human recombinant tumor necrosis factor alpha (TNF alpha) and all-trans-retinoic acid (RA) inhibit the in vitro clonal growth of human myeloid leukemic cells. We investigated the in vitro interaction of TNF alpha and RA with normal and a variety of leukemic myeloid cells. With the promyelocytic HL-60 cells, TNF alpha (greater than or equal to 2.5 U/mL) in combination with RA synergistically inhibited clonal growth; TNF alpha at lower concentrations (less than or equal to 1 U/mL) plus RA (10(-9) mol/L) were antagonistic in their inhibition of growth. The ability of RA (10(-8) mol/L) plus TNF alpha (2.5, 5 U/mL) to enhance differentiation of HL-60 cells paralleled their ability to inhibit clonal growth of these cells. In addition, RA (10(-9) to 10(-7) mol/L) increased the number of TNF alpha receptors on HL-60 cells 1.3- to 1.7-fold without changing the affinity for the TNF alpha receptor. With the more immature KG-1 myeloblasts, concentrations of TNF alpha greater than 10 U/mL synergistically interacted with RA to inhibit clonal growth; at lower concentrations of TNF alpha (less than 10 U/mL), RA appeared to inhibit the expected effect of TNF alpha. KG-1 cells were not induced to differentiate with either agent alone or in combination. With four of nine leukemic patients, TNF alpha in combination with RA (10(-7) mol/L) inhibited leukemic clonal growth to a greater extent than each agent alone. No marked effect of the combined treatment was seen in two other patients. The RA reversed the inhibitory action of TNF alpha on normal human granulocyte-macrophage colony forming cells (GM-CFC) and on clonal growth of leukemic cells from three patients. Our study suggests that TNF alpha and RA interact in a complex manner with normal and leukemic hematopoietic cells.

Cell Differentiation↗
PubMed1986

Simultaneous demonstration of two antigens on single T cells using antibodies with contrasting labels.

We describe a double labeling method for the discrimination of 2 antigens on single cells. It consists of a combination of 3H-immunoautoradiography and immunocytochemistry applied to cells previously fixed on poly-L-lysine (PLL)-coated multispot slides. The method has been applied to various mouse cells contemporaneously labeled with 2 different monoclonal antibodies. In order to distinguish the attached antibodies unambiguously, they were labeled with contrasting markers. One of the antibodies was marked with tritium blackening the photographic film that covers the slide. The other was detected with the peroxidase-anti-peroxidase (PAP) method forming a reddish precipitate. The contrast between the reddish reaction product of the PAP-labeled antibody and the black silver grains allows cells, specifically labeled with both antibodies, to be distinguished from cells labeled with only one or neither of the antibodies. Tritium-labeled antibodies were introduced because of their advantage over antibodies labeled with iodine in the closer localization of the silver grains to the bound antibody and their much longer halflife (60 days versus 12 years). In this study we applied a tritium-labeled anti-Thy-1.1 together with anti-Lyt-1 monoclonal antibody for studying the distribution of the corresponding antigens on lymphocytes in the mouse thymus and lymph node cells.

Animals↗
PubMed1986

Vitamin D compounds. Effect on clonal proliferation and differentiation of human myeloid cells.

We examined the effect of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) and a variety of vitamin D analogs on proliferation and differentiation of normal and leukemic myeloid clonogenic cells. Only cells from myeloid leukemic lines that contained relatively mature cells (HL-60, U937, THP, HEL, M1) were induced to differentiate and were inhibited in their clonal growth by exposure to 1 alpha,25(OH)2D3 (50% inhibition, 3 X 10(-8)-8 X 10(-10) M). A fluorinated analog of vitamin D was 5-10-fold more potent than 1 alpha,25(OH)2D3. Cells from a human myeloblast line (KG-1) and normal human granulocyte-monocyte stem cells (GM-CFC), both of which depend on colony-stimulating factor (CSF) for clonal growth, were stimulated in their clonal proliferation by 1 alpha,25(OH)2D3 in the presence of suboptimal concentrations of CSF. Leukemic cells from 10 of 14 patients with myeloid leukemia, but not normal GM-CFC from 12 patients in remission, were markedly inhibited in their clonal proliferation by 1 alpha,25(OH)2D3. Our results suggest that 1 alpha,25(OH)2D3 may be a cofactor in hematopoiesis and that vitamin D analogs may have a differential effect on normal versus leukemic growth.

Calcitriol↗
PubMed1986

Induction of features characteristic of hairy cell leukemia in chronic lymphocytic leukemia and prolymphocytic leukemia cells.

In vitro maturation was induced with 12-O-tetradecanoylphorbol-13-acetate in leukemic cell samples from patients with chronic lymphocytic leukemia (n = 10) and prolymphocytic leukemia (n = 4). The cells were studied for morphology, for immunological markers using the fluorescence activated cell sorter, and for acid phosphatase isoenzymes using both cytochemistry and isoelectrofocusing. Morphologically the induced changes included appearance of cells with an excentric nucleus and basophilic cytoplasm and eventually of cells with many fine cytoplasmic projections ("hairs"). Analysis of immunological markers by flow cytometry revealed that the monoclonal antibody defined cell surface molecule HD6 (CD22), which is strongly expressed on hairy cell leukemia (HCL) but absent from plasmacytoma and plasma cells, can be induced or enhanced in the leukemic samples. In the study of acid phosphatase isoenzymes using cytochemistry we observed the induction of the tartrate resistant isoenzyme. Further, using isoelectrofocusing we could demonstrate the induction of the same band of tartrate resistant acid phosphatase with an isoelectric point of 9.0-9.7 as detected also in HCL. This particular isoenzyme is considered characteristic of HCL but is absent in plasmacytoma. Our data demonstrate that chronic lymphocytic leukemia and prolymphocytic leukemia cells can be induced to realize a common genetic program which bears characteristics of HCL, indicating that these three entities are much more closely related than previously thought.

Acid Phosphatase↗
PubMed1985

In-vitro induction of some features of hairy cell leukemia in chronic lymphocytic leukemia and immunocytoma cells.

In an attempt to induce in vitro differentiation we exposed cells from patients with chronic lymphocytic leukemia (CLL) and with immunocytoma (IC) to 12-0-tetra-decanoylphorbol-13-acetate (TPA) at 160 nM. After 3 to 5 days of culture cells became enlarged and the CLL cells developed a basophilic cytoplasm with an excentric nucleus. In some instances cells with many fine projections were seen. We then employed the monoclonal antibody (MAB) HD 6, which was generated against hairy cell leukemia (HCL) cells and reacts most strongly with such cells but is unreactive with plasmocytoma cells and with most CLL cells. TPA treatment induced a greatly enhanced HD 6 binding in CLL and IC cells compared to controls as demonstrated by indirect immunofluorescence. Cytochemical studies revealed that at the same time an acid phosphatase was induced, which was found to be tartrate-resistant in every instance tested. Thus, several features of HCL can be induced in CLL and IC demonstrating the close relatedness of these entities.

Cell Differentiation↗
PubMed1985

Killer cell activity of human monoblastic leukemia cells as detected with a monocyte-specific target cell.

Peripheral blood leukemia cells from patients with acute monoblastic leukemia (AMoL) were tested for killer cell activity against target cells that detected natural killer cell-mediated or monocyte-mediated spontaneous cytotoxicity. The fibrosarcoma cell line Wehi 164, pretreated with actinomycin D to induce susceptibility to lysis, specifically detects the activity of unstimulated human monocytes. In four of six cases of AMoL, high killer cell activity could be measured against this target. In three of these four cases, the killer cell activity could be assigned exclusively to the leukemic clone, based on the high leukocyte counts and the resultant dilution of normal cells, as evidenced by marker and by functional analysis. While leukemic cells with killer cell activity against Wehi 164 contained 34% to 45% cells that were positive for binding of the 63D3 monoclonal antibody, the two leukemic samples without killer cell activity contained only 1% and 12% 63D3-positive cells. Cell sorting of 63D3-positive and -negative cells from two leukemias with killer cell activity demonstrated that the killer cell activity was restricted to the 63D3-positive fraction of AMoL cells. These data demonstrate that monoblastic leukemia cells can be potent killer cells and that killing activity is linked to the 63D3-defined cell surface molecule.

Animals↗
PubMed1985

Patients with a deficiency of natural killer cell activity lack the VEP13-positive lymphocyte subpopulation.

Many patients with B-type chronic lymphocytic leukemia (CLL) exhibit a profound defect in their natural killer (NK) cell activity, the basis of which is still obscure. Hence, we analyzed the NK cells from peripheral blood samples from 11 patients with CLL for phenotype and function, after removal of the leukemic cells with a monoclonal antibody (BA-1) plus complement. Phenotypic analysis of these nonleukemic cells with monoclonal antibodies (MoAbs) against NK cells revealed that the CLL patients had higher percentages of HNK-1-positive cells (23.5% compared to controls with 14.7%). In contrast, VEP13-positive cells were absent or low in seven patients (0.8% compared to controls with 11.2%) and normal in four patients (10.5%). When testing NK cell activities against K562 or MOLT 4 target cells, patients with no or minimal numbers of VEP13-positive cells were found to be deficient, while patients with normal percentages of VEP13-positive cells had NK cell activity comparable to controls. Isolation by fluorescence-activated cell sorter of HNK-1-positive cells from patients lacking VEP13-positive cells and NK cell activity indicated that the majority of the HNK-1-positive cells in these patients had the large granular lymphocyte morphology that is characteristic of NK cells. Thus, the deficiency of NK cell activity in CLL patients appears to result from the absence of cells carrying the VEP13 marker.

Antibodies, Monoclonal↗
PubMed1985

In vitro differentiation of human melanoma cells analyzed with monoclonal antibodies.

Many monoclonal antibodies (MABs) have been produced against cell surface molecules of melanoma cells, and these reagents might help in the definition of stages of differentiation of the normal and the malignant cells. In an attempt to detect MAB-defined determinants that modulate with differentiation, we treated nonpigmented human melanoma cells with the tumor promotor 12-O-tetradecanoylphorbol-13-acetate (TPA) at 16 nM. Differentiation could be induced in all 4 cell lines, as evidenced by growth retardation, development of projections, and induction of melanin or of premelanosomes in the projections as detected by transmission electron microscopy. Of the 9 MAB-defined cell surface antigens, three were shown to modulate with TPA-induced differentiation, as assessed by fluorescence microscopy and fluorescence-activated cell sorter analysis. Antigens detected by MABs 15.75 and 15.95 decreased in every one of the four cells after TPA induction of differentiation. The proteoglycan defined by 225.28S increased slightly in one, showed no change in another, and decreased in the remaining two. These three MAB-defined molecules thus are linked to differentiation and might help in designing a scheme of differentiation of the melanocyte lineage.

Antibodies, Monoclonal↗
PubMed1984

Development and properties of a monoclonal antibody specific for human ecto-5'-nucleotidase.

After immunization with purified human placental ecto-5'-nucleotidase and fusion, 18 different hybrids were obtained which produce an antibody inhibitory for enzyme activity. These antibodies show complete cross-reactivity with the enzyme in a membrane-bound form or on the surface of intact cells. After cloning and ascites production, the antibody of one clone ( IFH - 5N1 ) was studied in greater detail. The IFH - 5N1 antibody is of the IgG 1 subclass. Optimal enzyme inhibition is 90% for purified 5'-nucleotidase and 80% for the enzyme on lymphoblasts. The specificity of this antibody is further demonstrated by enzyme inhibition assays and fluorescence labeling using various 5'-nucleotidase-positive and -negative human cells such as peripheral blood lymphocytes, leukemic cells, lymphoblastoid B- and T-cell-lines and fibroblasts. The antibody should provide a useful tool for the diagnosis of certain forms of acute leukemias and for the study of normal human lymphocyte subpopulations.

5'-Nucleotidase↗
PubMed1984

The use of VEP13 monoclonal antibody for definition of natural killer cells: spontaneous killer cells directed against fresh human leukaemia cells carry the VEP13 antigen.

VEP13, an IgM monoclonal antibody (MoAb), produced against human large granular lymphocytes, is able to deplete natural killer (NK) cell activity in complement-dependent lysis. Here we report that VEP13 also reacts with the majority of interferon (IFN) activated NK cells. By contrast cytotoxic activity of unstimulated monocytes and cytotoxic T cells directed against allogeneic lymphocytes were unaffected by VEP13 plus complement treatment. Thus among the major types of cytotoxic cells VEP13 selectively reacts with NK cells and hence can be employed to identify these cells. We therefore used VEP13 in complement-dependent lysis and FACS separation to analyse NK cells involved in enhanced killing of fresh leukaemia cells. Spontaneous cell-mediated lysis of human leukaemia cells was enhanced in two ways: (a) effector cells were pre-treated with beta-IFN and (b) leukaemia cells were pre-treated with a pulse of actinomycin D. In complement-dependent lysis VEP13 removed all NK cell activity of IFN activated PBM against untreated and against ActD pre-treated leukaemia cells. FACS separation of VEP13 positive cells further supported this finding, in that all activity of IFN activated NK cells against actinomycin D pre-treated targets was found in the VEP13 positive fraction. Thus enhanced killing of fresh human leukaemia cells appears to be mediated VEP13 positive NK cells which are distinct from cytotoxic T cells and cytotoxic monocytes.

Antibodies, Monoclonal↗
PubMed1983

Crossreaction of monoclonal anti-T-cell antibodies: implications for classifying B-cell leukemias.

Cell samples from 62 patients with B-cell leukemias (33 CLL, 8 IC, 6 PLL, 4 HCL, 2 ALL and 9 other NHL) were tested with a series of monoclonal antibodies (A50, T101, Lyt2, Leu 1, M203) directed against T cells and shown to crossreact with B-CLL. The results demonstrate a heterogeneity of B-cell leukemias as all typical cases of CLL were reactive whereas most other cases were negative. Using the fluorescence-activated cell sorter, a somewhat stronger reaction was seen in early or benign cases of CLL, compared to advanced cases. All B-cell leukemias tested expressed the Ia antigen.

Adult↗
PubMed1983

Immunofluorescence with monoclonal antibodies on poly-L-lysine coated slides: an alternative to conventional methods.

It is sometimes difficult to perform immunofluorescence tests because of low cell numbers. Therefore a simple method using poly-L-lysine coated slides was applied to immunofluorescence and compared with the routine suspension method. Peripheral blood lymphocytes from normal persons, samples of normal bone marrow, thymus and tonsil as well as samples from patients with leukemia or lymphoma were tested with these two methods using 20 different monoclonal antibodies. The PLL-slide method was shown to be comparable with the suspension method and is an alternative in case of low cell numbers, since as few as 3 X 10(4) cells can be tested for one antigen.

Antibodies, Monoclonal↗
PubMed1983

Analysis with monoclonal antibodies of human lymphoid cells forming rosettes with rabbit red blood cells.

Rabbit red blood cells have previously been shown to rosette with a subpopulation of thymocytes and with mitogen activated peripheral lymphocytes but not with unstimulated lymphocytes. Using monoclonal antibodies and double marker assays we studied the phenotype of these cells. In thymus, over 90% of rosetting cells express antigens of immature thymocytes (HTA1, OKT6). A proportion of the rosetting cells shows in addition antigens of mature thymocytes (OKT3, UCHT1). These cells probably correspond to a stage of intrathymic maturation between common and mature thymocytes. Virtually all rosetting cells are T cells and express an antigen related to T cell activation (TAC) when lymphocytes are activated by mitogens like PHA or Con A. Few rosetting cells are Ia positive. Two other antigens (OKT9, OKT10) known to be associated with proliferating and immature cells, are found in variable proportions on rosetting cells. After stimulation with allogeneic lymphocytes, fewer rosettes are detected than after stimulation by mitogens. Cells activated by a soluble antigen (PPD) and forming rosettes with rabbit red blood cells have a helper phenotype (Leu3a positive). Screening of leukaemia cell samples revealed that only cells from patients with T-ALL form rosettes with rabbit red blood cells. Rosette formation is almost totally inhibited by a polyclonal anti-thymocyte serum and two monoclonal antibodies (OKT11A,Lyt3) which have been shown to block rosettes with sheep erythrocytes.

Animals↗
PubMed1982

Comparison of currently available monoclonal antibodies with conventional markers for phenotyping of one hundred acute leukemias.

One hundred acute leukemia cell samples (89 ALL, 11 AMML) derived from children's bone marrow at diagnosis were typed for the reaction with 15 monoclonal antibodies (mAbs). Subdivision in ALL-subgroups was performed according to conventional markers. Only some mAbs like VIL-Al which is directed against the cALL-antigen, can substitute polyclonal rabbit antisera. Additional subclassifications became evident by the use of mAbs for T-cell differentiated ALL forms. However, unexpected negative reactions must be taken into account as observed for all T-directed mAbs with individual T-cell ALL samples.

Acute Disease↗
PubMed1982

Characterization with monoclonal antibodies of human lymphocytes forming dog and rhesus-monkey rosettes.

Human peripheral-blood mononuclear cells forming rosettes with dog and rhesus-monkey red blood cells were characterized with a double marker analysis combining immunofluorescence with a series of monoclonal antibodies and rosette formation. Dog rosette-forming cells are a minor subset of T cells which does not correspond to the helper or suppressor subsets of T cells as determined by the OKT antibodies. Dog rosette formation can be inhibited by two monoclonal antibodies directed against the receptor for sheep red blood cells on human lymphocytes. Rhesus-monkey rosettes can be formed by T lymphocytes as well as by monocytes, null cells, and B cells, as determined by the reactivities with the monoclonal antibodies OKM1 and anti-Ia. OKM1-positive cells are relatively enriched in these rosettes. No inhibition is seen with antibodies directed against the receptor for sheep red blood cells. In conclusion, we demonstrated with the use of monoclonal antibodies that dog and rhesus-monkey rosettes are qualitatively different phenomena.

Animals↗