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T Plesner

Publications and source records attributed to T Plesner.

At least 19 recordsLinked to original sources
PubMed1992

A soluble form of the glycolipid-anchored receptor for urokinase-type plasminogen activator is secreted from peripheral blood leukocytes from patients with paroxysmal nocturnal hemoglobinuria.

The cellular urokinase-type plasminogen-activator (uPA) receptor (uPAR) is a glycolipid-anchored membrane protein thought to be involved in pericellular proteolysis during cell migration and tumor invasion. In the present study, we have identified and characterized two soluble forms of uPAR which have retained their ligand-binding capability. One variant was generated in vitro by treatment of intact normal cells with either a phosphatidylinositol-specific phospholipase C (PLC) or endoproteinase Asp-N. The other soluble uPAR variant was secreted in vivo from peripheral blood leukocytes affected by the stem-cell disorder paroxysmal nocturnal hemoglobinuria (PNH), and was found in the plasma from these PNH patients as well as in the conditioned medium from cultured PNH leukocytes. Under normal conditions, we find no evidence for any shedding or secretion of a soluble uPA-binding counterpart to human uPAR in plasma. Unlike normal leukocytes, the PNH-affected cells do not express uPAR on the cell surface, although they do contain apparently normal levels of uPAR-specific mRNA. The secreted uPAR derived from PNH cells has a mobility in SDS/PAGE that is slightly higher than that of uPAR solubilized by PtdIns-specific PLC or detergent, but resembles that of a truncated, recombinant uPAR variant, which has its C-terminus close to the proposed glycolipid-attachment site, suggesting that the secreted protein has been proteolytically processed for glycolipid attachment. The presence in plasma from PNH patients of such a secreted, hydrophilic form of uPAR lends support to the hypothesis that the lesion underlying the PNH disorder resides either in glycolipid biosynthesis or in the function of an as-yet-unidentified transamidating enzyme assumed to cleave and assemble the truncated uPAR with the preformed glycolipid moiety.

Amino Acid Sequence↗
PubMed1992

The receptor for urokinase-type plasminogen activator is deficient on peripheral blood leukocytes in patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal defect in bone marrow-derived cells and is clinically associated with intravascular hemolysis, hemoglobinuria, and an increased frequency of venous thrombosis. The common denominator of PNH-affected blood cells appears to be a defect in the membrane attachment of proteins normally anchored by glycosyl-phosphatidylinositol (GPI). We report here that the cellular receptor for urokinase-type plasminogen activator (u-PAR) is deficient on affected peripheral blood monocytes and granulocytes from four individuals with PNH as evidenced by chemical cross-linking analysis as well as by immunofluorescence flow cytometry using a monoclonal anti-u-PAR antibody. In contrast, on normal blood monocytes and granulocytes we find significant amounts of u-PAR, which is attached to the plasma membrane by a GPI-anchor as defined by its sensitivity towards a specific phospholipase treatment. By two-color flow cytometry it was shown that deficiency of u-PAR expression paralleled that of another GPI-anchored protein. As u-PAR is involved in the initiation of pericellular proteolysis, the reduced expression of u-PAR on PNH-affected leukocytes led to an overall reduction in the capacity for plasminogen activation by cell-surface-bound urokinase. Whereas the abnormal susceptibility of PNH-affected erythrocytes to lysis by autologous complement has been related to the low expression of three GPI-anchored complement regulatory proteins on the cell surface, we now propose that lack of u-PAR expression on the surface of peripheral blood leukocytes may be causally related to the high incidence of venous thrombosis observed in PNH patients.

Animals↗
PubMed1992

Increased yield of myeloid progenitor cells in bone marrow harvested for autologous transplantation by pretreatment with recombinant human granulocyte-colony stimulating factor.

Pretreatment with haemopoietic cytokines prior to marrow harvest may result in improved quality of bone marrow harvested for autologous bone marrow transplantation (BMT). Such improvements may reduce the risk for graft failure and decrease time to engraftment. Patients undergoing autologous BMT received recombinant human G-CSF (rhG-CSF) immediately prior to marrow harvest. rhG-CSF was administered as daily subcutaneous injections for 5 days at 5 micrograms/kg body weight. Comparison of bone marrow samples before and after rhG-CSF treatment showed an increased bone marrow cellularity and a ninefold increase in the number of marrow leucocytes per volume aspirated. The mean marrow myeloid:erythroid ratio increased from 2.6 to 4.0. The mean numbers of immature (CD38 positive) and proliferating (CD71 positive) myeloid cells increased significantly from 41.6 to 50.8% and from 17.0 to 34.8%, respectively. Other subsets studied, including CD34 positive stem cells, were unchanged. The relative numbers of day 7 and 14 granulocyte-macrophage colony-forming units (day 7/14 GM-CFU) were unchanged. Long-term marrow cultures revealed that the numbers of 'long-term culture initiating cells' were unchanged after rhG-CSF treatment in spite of the ninefold increase in cellularity. To date, five of the patients have been transplanted with autologous marrow harvested after rhG-CSF treatment. Time to trilineage engraftment was unchanged compared with historical controls. We conclude that pretreatment with rhG-CSF prior to marrow harvest may improve the graft by increasing the total number of myeloid lineage restricted progenitor cells, resulting in stable but not accelerated myeloid engraftment of autologous marrow.

Bone Marrow Transplantation↗
PubMed1991

Prognostic importance of flow cytometric immunophenotyping of 540 consecutive patients with B-cell chronic lymphocytic leukemia.

Blood mononuclear cells from 540 newly diagnosed, unselected patients with B-cell chronic lymphocytic leukemia (CLL) were examined by immunofluorescence flow cytometry for a panel of surface membrane markers, including IgM and IgD, the monoclonal antibodies anti-CD3, -5, -20, -21, -22, -FMC7, and, for the final 125 patients, anti-CD23. There were 503 CD5+ and 37 CD5- cases. In the CD5+ cases, the cells typically expressed IgM, IgD, CD20, CD21, CD22, and CD23. In univariate analysis, age, clinical stage, IgM-fluorescence intensity, CD23, and FMC7 had significant prognostic importance, with high IgM-fluorescence intensity, high FMC7, and low CD23 expression being associated with a short survival. There was no significant difference in survival between 351 cases expressing IgMD and 55 cases expressing IgM without IgD, or between kappa and lambda light chain monoclonal cases. CD20, CD21, and CD22 had no prognostic importance. In Cox multiple regression analyses, age, CD23, IgM-fluorescence intensity, and clinical stage (International Workshop System) had independent prognostic importance. Thus, besides clinical variables, CD23 and IgM intensity might be useful prognostic markers in the management of CD5+, B-cell CLL. The survival of CD5- patients was on the borderline of being significantly shorter than that of CD5+ patients. The majority of the CD5- cases were FMC7+, CD23-, had strong IgM fluorescence, and had splenomegaly.

Aged↗
PubMed1990

T cell activation. II. Activation of human T lymphoma cells by cross-linking of their MHC class I antigens.

The present work demonstrates that antibody-induced cross-linking of MHC class I antigens on Jurkat T lymphoma cells leads to a rise in intracellular calcium (Cai2+) and, in the presence of phorbol ester (PMA), to IL-2 production and IL-2 receptor expression. The rise in Cai2+ exhibited a profile very different from that obtained after anti-CD3 antibody-induced activation suggesting that activation signals are transduced differently after binding of anti-CD3 antibody and class I cross-linking, respectively. However, when Cai2+ was examined in individual Jurkat cells by means of a digital image processing system no differences were observed after cross-linking with anti-CD3 and anti-MHC class I antibodies, respectively. Two CD3-negative mutant lymphoma lines were nearly totally refractory to class I cross-linking. Taken together our results may indicate the existence of a functional linkage between the T cell receptor complex and MHC class I molecules.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Estimation of PI-bound proteins on blood cells from PNH patients by quantitative flow cytometry.

The phosphatidylinositol (PI) bound proteins (acetylcholin-esterase (ACE), decay accelerating factor (DAF), leucocyte function antigen type 3 (LFA-3) and Fc-receptor type III (FcRIII] were estimated by flow cytometry on blood cells from four patients with paroxysmal nocturnal haemoglobinuria (PNH), nine patients with 'non-PNH' haemolytic anaemia, four patients with aplastic anaemia and a reference group of 15 healthy individuals to assess the applicability of flow cytometric measurements in the clinical mapping of the PNH defect. Estimation of DAF on granulocytes or monocytes offered the highest diagnostic sensitivity and specificity and may constitute an easy screening method for the PNH defect. One PNH patient had a negative Ham's test at the time of study and normal or near normal levels of PI-bound proteins on erythrocytes, but reduced expression of DAF and FcRIII on granulocytes and DAF on monocytes. The analytical and biological coefficient of variation for flow cytometric estimation of PI-bound proteins was in the range of 4.8-13% and 12-24%, respectively. Blood samples should be analysed without delay, since storage produced spuriously high results. The results were expressed as molecules per cell after calibration with commercially available standards and validated by comparison with previously reported results obtained by other methods. It is proposed that this way of reporting flow cytometric results should be generally adopted to facilitate comparison of results between laboratories.

Acetylcholinesterase↗
PubMed1990

T-cell activation. III. Attempts to activate MHC class I-negative and class I-transfected EL4 T-lymphoma cells by immobilized anti-CD3 antibody.

The aim of this study was to examine whether the unresponsiveness of MHC class I-negative subclones of the EL4 thymoma to CD3 cross-linking can be restored by transfection of class I genes into the H-2-negative cells. Cell activation experiments with selected MHC class I-negative subclones and H-2b- and H-2Ld-positive transfectants showed that these cells are equally capable of secreting interleukin 2 (IL-2) after exposure to the phorbol ester phorbol 12-myristate 13-acetate (PMA) and ionomycin. In contrast, only the parental H-2-positive EL4 cells are capable of responding to treatment with immobilized anti-CD3 antibody with IL-2 secretion and IL-2 receptor expression. Measurements of intracellular free Ca2+ (Ca2+i) following anti-CD3 antibody-induced cross-linking of parental EL4 cells and H-2-negative and H-2b gene-transfected subclones showed that the parental cells and two of the class I transfectants, one H-2-positive and one H-2-negative, responded with a slow rise in Ca2+i, whereas one H-2-positive transfected cell clone was completely refractory to CD3 cross-linking. Modulation experiments using parental EL4 cells, H-2-negative subclones and H-2-positive transfectants demonstrated that the CD3 and class I molecules of these different cells are modulated to the same extent after exposure to specific antibodies. The present findings thus indicate that the unresponsiveness of H-2-negative EL4 subclone cells to CD3 cross-linking is not functionally associated with a lack of class I surface expression.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

Transmembrane signalling via HLA-DR molecules on T cells from a Sezary T-cell leukaemia line.

The human Sezary T-cell leukaemia line, HUT.78, represents a population of activated T cells, i.e. they are HLA-DR+ and IL-2R+. We have analysed the capacity of HUT.78 cells (1) to stimulate HLA-DR-specific T-cell lines or clones and (2) to be induced to synthesize IL-2 by anti-HLA-DR monoclonal antibodies. The results of our experiments show that HLA-DR molecules on HUT.78 cells can stimulate at least one HLA-DR-specific T-cell clone and can act as transmembrane signal transmitters.

Antibodies, Monoclonal↗
PubMed1990

Quantitative buffy coat analysis in haematological patients compared to standard laboratory methods.

We have tested a Quantitative Buffy Coat (QBC) instrument (Becton Dickinson, USA), and compared results obtained with this instrument to results obtained with standard methods in a haematology clinic. The basic principle of the method is a classical haematocrit centrifuge. The analysis provides a haematocrit value, platelet count, a total white blood count, and separates the white blood cells in granulocytes and mononuclear cells (lymphocytes plus monocytes). The instrument is easy to use but requires a trained observer. All results are available in 15 min. We have found the accuracy of the method good for all parameters. The precision of the instrument is good but for estimation of granulocytes and lymphocytes plus monocytes we did not find the high sensitivity claimed by the manufacturer (manufacturer's lower limit 0.02 x 10(9)/l; standard deviation for low levels of granulocytes: 0.300 x 10(9)/l and lymphocytes plus monocytes: 0.235 x 10(9)/l). A large fraction of samples (leukocytes 27%, platelets 40%) from a haematological clinic falls beyond the limits for reliable results set by the manufacturer, which reduces the utility of the instrument in such patients. Furthermore, in 21% and 10% of samples within the recommended range for leukocytes and platelets, respectively, QBC results could not be read owing to ill-defined boundaries. For granulocytes and lymphocytes plus monocytes 25% and 34% of the samples, respectively, could not be read owing to ill-defined boundaries. The instrument is not constructed to protect against blood contamination of the centrifuge and, therefore, the safety of the instrument is not satisfactory.

Blood Cell Count↗
PubMed1989

Fractionation of T cell subsets on Ig anti-Ig columns: isolation of helper T cells from nonresponder mice, demonstration of antigen-specific T suppressor cells, and selection of CD-3 negative variants of Jurkat T cells.

In the present experiments we have explored the possibilities of a modified immunoadsorbent technique to select for (1) mutagenized T cell receptor (Tcr) negative variants of Jurkat T lymphoma cells and (2) purified CD-4+ or CD-8+ T lymphocytes. The basic principle was to make large numbers of immunoglobulin (Ig) negative T cells Ig+ by T cell subset-specific monoclonal antibodies (mAb), and to select such cells on Ig anti-Ig columns. Our results demonstrated that Thy-1+, Fc receptor positive, antigen-specific T cells regulate the immune response in mice nonresponders to pork insulin, and the "autologous" mixed lymphocyte reaction. In addition, the immunoadsorbent method very efficiently selects Tcr/CD-3- variants from mutagenized Jurkat cell populations incubated with anti-CD3 mAb. The described method is easy and quick and can fractionate large numbers of cells; it is the "poor-man's cell sorter." The most important finding is the demonstration of antigen-specific Thy-1+, CD-8+, and Fc receptor+ T suppressor cell that apparently react with antigen in a non-major histocompatibility complex-restricted manner.

Animals↗
PubMed1989

Specific depletion of mature T lymphocytes from human bone marrow.

An effective method for specific depletion of mature T lymphocytes from human bone marrow mononuclear cells (BMMC) with preservation of prethymic T cells and natural killer (NK) cells is presented. The BMMC were incubated with F101.01, a monoclonal antibody recognizing an epitope of the T-cell receptor-CD3 complex, and subsequently with immunomagnetic beads. Flow cytometric analysis demonstrated that mature T cells were efficiently depleted and that NK cells and prethymic T cells were preserved in the BMMC. Furthermore, T cell-mediated immune reaction as measured by thymidine incorporation after stimulation with phytohaemagglutinin was abolished, whereas NK activity as measured by 51Cr release using K562 as target cells was preserved. Recovery of colony-forming units of granulocyte-macrophages was 60-70%.

Bone Marrow↗
PubMed1989

Failure to synthesize the human T-cell CD3-zeta chain and its consequence for the T-cell receptor-CD3 complex expression.

The T-cell antigen receptor is composed of two variable chains (alpha and beta, termed TcR) which confer ligand specificity, and four constant chains (gamma, delta, epsilon, and zeta, collectively termed CD3) whose functions are not fully understood. To explore the role of the individual CD3 components, the human T-cell tumour line Jurkat was chemically mutagenized followed by negative selection with F101.01 (a monoclonal antibody against the TcR-CD3 complex), and cloning. Growing clones were analysed for TcR-CD3 expression by immunofluorescence. One clone, J79, was found to express greatly diminished levels of TcR-CD3. This clone produced all the TcR-CD3 components except the CD3-zeta, as demonstrated by metabolic labelling and immunoprecipitation followed by one- and two-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis. These data indicate that the CD3-zeta determines the normal intracellular fate of the TcR-CD3 complex, and that the CD3-zeta is necessary for the intracellular transport and expression at the cell surface of the TcR-CD3 complex.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1989

Novel primary thymic defect with T lymphocytes expressing gamma delta T cell receptor.

Flow cytometric analysis of the peripheral blood mononuclear cells in a six year old girl with a primary cellular immune deficiency showed a normal fraction of CD3 positive T cells. Most (70%) of the CD3 positive cells, however, expressed the gamma delta and not the alpha beta T cell receptor. Immunoprecipitation and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that most of the gamma delta T cell receptors existed as disulphide-linked heterodimers. Proliferative responses to mitogens were severely reduced, but specific antibody responses after vaccination could be detected. A thymic biopsy specimen showed severe abnormalities of both the thymic lymphoid and epithelial component with abortive medullary differentiation and almost an entire lack of Hassall's corpuscles. This patient represents a case of primary immune deficiency syndrome not previously described. Thymic deficiency associated with a high proportion of T cells expressing the gamma delta T cell receptor has been described in nude mice, and it is suggested that the immune deficiency of this patient may represent a human analogue.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

Identification of alpha beta and gamma delta T cell receptor-positive cells.

Two lineages of T lymphocytes bearing the CD3 antigen can be defined on the basis of the nature of the heterodimeric receptor chain (alpha beta or gamma delta T cell receptor (TCR) expressed. Precise identification of alpha beta and gamma delta TCR+ cells is essential when studying the tissue distribution and function of these different T cells. In immunofluorescence studies gamma delta TCR+ cells have been identified as CD3+WT-31- or CD3+CD4-CD8- cells. However, this may not be the optimal procedure because gamma delta TCR+ cells are weakly WT-31+, and some are CD8+. The aim of this study was to evaluate a panel of monoclonal antibodies (MoAb) directed against different chains of the TCR-T3 complex for a more precise identification of alpha beta+ and gamma delta TCR+ cells in flow cytometric studies. We found that the MoAb anti-Ti-gamma A and delta-TCS-1, recognizing the TCR-gamma and the TCR-delta chain respectively, only reacted with a subpopulation of gamma delta TCR+ cells, whereas another TCR-delta chain recognizing MoAb anti-TCR-delta 1 reacted with all gamma delta TCR+ cells. All MoAb reported to belong to the CD3 group reacted with both alpha beta TCR+ and gamma delta TCR+ cells as expected. Our results indicate that all gamma delta TCR+ cells can be identified with the MoAb anti-TCR-delta 1. Because no MoAb recognizing the TCR-alpha or TCR-beta chains at the cell surface of intact cells are yet available, we suggest that alpha beta TCR+ cells could be identified as CD3+ anti-TCR-delta 1-cells.

Antibodies, Monoclonal↗
PubMed1988

Characterization and expression of the human T cell receptor-T3 complex by monoclonal antibody F101.01.

A murine monoclonal antibody (MoAb) F101.01 reacting with the T cell receptor (TCR)-T3 complex is presented. Immunohistological studies showed that F101.01 specifically stains T-zone lymphocytes in lymph nodes, tonsils, and splenic tissue. Two-colour immunofluorescence and flow cytometry demonstrated co-expression of the antigen defined by F101.01 and the pan-T cell antigens defined by CD2, CD3, CD5, and CD7 antibodies. Cells stained with CD4 and CD8 antibodies were both included in the F101.01-positive population, whereas CD16-positive natural killer cells (NK), B cells (CD19 and CD20), and myeloid cells (CD13 and CD33) were excluded. The target antigen of F101.01 co-modulated with the CD3-defined antigen (T3) and the TCR recognized by the MoAb WT-31. CD3 antibody and WT-31 both blocked binding of F101.01. F101.01 precipitated the TCR-T3 complex from lysates of 125I-labelled peripheral blood mononuclear cells (PBMC) and HPB-ALL, when the lysate was prepared with a detergent (digitonin) that conserves the TCR-T3 complex. FACS analysis of T cells from a patient with a T cell immunodeficiency demonstrated that delta-TCS-1-CD3+CD4+ and delta-TCS-1-CD3+CD8+ cells were brightly F101.01+, whereas a large subpopulation of delta-TCS-1+CD3+CD4-CD8- cells were weakly F101.01+. We conclude that F101.01 recognizes a conformational epitope of the TCR-T3 complex and that it reacts with the alpha beta TCR-T3 and the gamma delta TCR-T3 complexes with different intensities.

Antibodies, Monoclonal↗
PubMed1988

The CLL2 study: preliminary results of flow cytometry immunophenotyping in the first 500 patients.

In the period 1984-1987, 500 consecutive, newly diagnosed patients with chronic lymphocytic leukaemia (CLL) have been registered in the still open Danish CLL2-study. As part of patient work-up, the immunological phenotype was established in all patients by immunofluorescence microscopy, and in 458 patients also by flow cytometry, with a panel of polyclonal and monoclonal antibodies. The majority of cases exhibited a CD5-pos, SmIgMD-pos phenotype with faint SmIg-fluorescence, and there is as yet no significant difference in survival between SmIgD-pos and SmIgD-neg cases. Seventy cases were FMC7-pos, a marker associated with a higher B-cell differentiation, and this was significantly correlated with stronger SmIg fluorescence intensity and splenomegaly (Rai stage II). The survival of the FMC7-pos patients was not significantly different from that of the FMC7-neg. Thus, in this preliminary phenotype analysis of the first 500 patients in the CLL2 study, no important prognostic subgroups were detected, although this might be due to the still short observation time (median observation time 532 days).

Denmark↗
PubMed1987

Lack of prognostic significance of T-lymphocyte subset counts in B-cell chronic lymphocytic leukaemia.

In the 50 newly diagnosed, unselected, untreated B-CLL patients, the absolute numbers of blood T cells, T-helper cells, and T-suppressor/cytotoxic cells were by flow cytometric counting of mononuclear cells labelled with the monoclonal antibodies Leu5 (T cells), Leu3a (T-helper cells), and Leu2a (T-suppressor/cytotoxic cells). These estimations and the serum concentrations of IgG, IgA, and IgM were correlated to clinical stage (International Workshop System) and pretreatment observation time. For all patients together, the mean counts of Leu5+, Leu3+, and Leu2+ cells were significantly increased compared with the mean counts in 12 healthy controls (Mann-Whitney). In patients with advanced disease (stage B + C), both T-subset mean cell counts were significantly increased, whereas in patients with early-stage disease (stage A), although some high T-helper cell counts were noted, only the T-suppressor/cytotoxic mean cell count increase reached significance. Thus a trend was observed of a more frequent T-suppressor/cytotoxic cell predominance in early-stage disease, which is the opposite of the findings in most other prognostic studies. However, there was no significant difference in pre-treatment observation time according to T-helper: T-suppressor cell ratio below vs. above 1.0, irrespective of stage, whereas according to clinical stage, the pretreatment observation time in stage A was highly significantly longer than in stage B + C (logrank test). Thus, no independent prognostic significance of T-subset counts was found as judged by pretreatment observation time. No correlation was found between the occurrence of hypogammaglobulinaemia, T-subset ratios or T-subset counts.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗