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Biomedical subjects

M Benczur

Publications and source records attributed to M Benczur.

At least 19 recordsLinked to original sources
PubMed1990

[Cytochemical, immunologic and gene rearrangement studies in adult acute leukemia].

Results of morphological, cytochemical and immunological studies performed in adult acute leukaemias have been compared. Thirty one cases proved to be acute myeloid leukaemia, while 25 cases were shown to be acute lymphoid leukaemia. Based on our results we conclude that immunophenotyping with monoclonal antibodies does not help in distinguishing the subtypes of AML. For purposes of clinical diagnosis cytochemical methods are valuable. On the other hand the monoclonal antibodies are essential in distinguishing the very immature myeloid and lymphoid leukaemias and this is of great importance from the clinical point of view, in determining therapy. Moreover, the diagnosis of acute lymphoid leukaemias is not possible without the specific monoclonal antibodies. Their application is first of all in haematological centers caring for leukaemia patients nowadays already obligatory. Gene rearrangement studies make the diagnosis more accurate and help in the diagnosis of leukaemias of unknown immunological origin.

Adult↗
PubMed1990

Observations on NK cells, K cells and on their function a long time after posttraumatic splenectomy.

Natural killer (NK) cell activity and antibody-dependent cellular cytotoxicity of 48 posttraumatic splenectomy patients was found to be normal despite the increase in the proportion and the absolute number of large granular lymphocytes (LGLs). The NK cell activity of 2 further posttraumatic splenectomy cases was severely decreased, despite elevated number of LGLs and normal number of CD16+ peripheral blood mononuclear cells. Besides increased susceptibility to upper respiratory tract infections, 1 of these patients developed herpes genitalis recidivans. Two posttraumatic splenectomy patients were found to have developed chronic lymphocytic leukemia 5 and 31 years following splenectomy, respectively.

Adult↗
PubMed1990

Clinical value of cytomorphologic, immunologic and cytogenetic investigations of acute leukaemias.

The valuability of immunophenotyping of acute myeloid and lymphoid leukaemias in comparison to morphological and cytochemical classification were approached in 56 cases. In the case of acute myeloid leukaemias the immunophenotyping by monoclonal antibodies CD14, CD13, CD33 was less informative concerning the subtypes of the disease. The clinical diagnosis can be achieved on the basis of cytochemical investigation alone. In contrast, the diagnosis of lymphoid leukaemias requires all information obtained by immunophenotyping by a series of monoclonal antibodies CD3, CD2, CD4, CD8, CD1, CD19, CD20, CD21 and CD10. On the other hand, the monoclonal antibodies are essential in differentiation of the very immature myeloid and lymphoid leukaemias. This is of great importance from the clinical point of view for determining the therapy. Molecular genetic studies based on the characterisation of the state of gene rearrangement of immunoglobulin and T-cell receptor beta chains have basic importance in the confirmation of the result of immunophenotyping and in the determination of leukaemias of unknown origin.

Acute Disease↗
PubMed1989

Cercopithecus aethiops monkey as a reliable model for in vitro study of T cell depletion of bone marrow with Campath-1 plus complement.

T-lymphocyte markers of peripheral blood mononuclear cells (PBMCs) and bone marrow mononuclear cells (BMMCs) of C. aethiops monkeys were studied by using anti-human monoclonal antibodies. The results show that C. aethiops T lymphocytes express surface markers which react specifically with anti-human MoAbs including CD3, CD4, CD8, CD2. However, very few CD3-positive cells were found, in contrast to the abundance in CD8+ cells. There is a high conservation of receptors forming E rosettes with AET-treated SRBCs, and antigens reacting with the anti-human T and B cell monoclonal antibody (Campath-1). The present findings indicate that C. aethiops can be used as a new experimental model for studies on T-cell depletion from bone marrow with Campath-1 MoAb + rabbit C.

Animals↗
PubMed1989

Human fetal liver as a valuable source of haemopoietic stem cells for allogeneic bone marrow transplantation.

The CFU-GM and T cell contents of human fetal livers were studied at various times between 6-14 weeks of gestation. The number of CFU-GM increased parallel to gestational age, especially after week 10. Cells bearing mature T cell markers, however, were found only in one case out of 35 fetal liver samples. Cryopreservation of fetal liver cells hardly affected the viability and proliferative capacity of CFU-GM in the sample. According to these findings fetal liver is, at least up to the 14th gestational week, practically free of mature T cells but it does contain a considerable amount of CFU-GM (an accepted indicator of pluripotent stem cell content), consequently fetal liver can be considered as a valuable source of haemopoietic stem cells for allogeneic bone marrow transplantation for children.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1988

The different effect of alpha and gamma interferons and interleukin 2 on the expression of CD2, CD3, CD4 and CD8 antigens in comparison to histocompatibility antigens of human lymphocytes.

The effects of alpha- and gamma-interferons (IFN-alpha, -gamma) and of interleukin 2 (IL-2) on the expression of certain differentiation antigens were compared with those of major histocompatibility antigens on human lymphocytes. IFN-gamma and IFN-alpha in high doses significantly increased the expression of T11 (CD2) differentiation antigen, but did not affect the expression of T4 (CD4), T8 (CD8), T3 (CD3) and Leu-7 antigens (HNK-1). Both natural and recombinant IFN-alpha and -beta apparently increased the expression of HLA-ABC antigens and of beta-2 microglobulin (beta 2m) after 16 h incubation. The amount of HLA-DR antigen, however, doubled in a few hours following IFN-gamma treatment. IL-2 affected the expression of CD2 and CD8 antigens only marginally, but did not affect that of CD3 and Leu-7; however, it strongly enhanced the expression of HLA-ABC, HLA-DR, and beta 2m antigens.

Antigens, Differentiation↗
PubMed1988

DNA synthesis and nucleoside metabolism in human tonsillar lymphocyte subpopulations.

High (HD) and low (LD) density cells were separated on 25% BSA gradient from tonsils of 3-6 years old children. Early B lymphocyte markers and sIg-s were found on the surface of 59-82% of the LD cells. This cell population was 5-6 times more active in DNA synthesis (3H-thymidine incorporation, DNA polymerase activity) than the HD cells. The total uptake of 3H-deoxycytidine was about the same as that of 3H-thymidine. As long as practically all thymidine taken up by the cells was immediately incorporated into DNA (90-95%), only 10-15% of deoxycytidine was incorporated into DNA under the same conditions, indicating different pool sizes for the DNA precursors. The majority of deoxycytidine (70%) was converted and incorporated as dTMP. A considerable part of labeled deoxycytidine could be detected in the soluble pool in form of nucleotides (3-8%), and in an unknown form, called substance X (8-14%). Substance X was purified by TL chromatography and identified by HPLC as deoxycytidine containing liponucleotides, probable precursors for plasmamembranes. The preferential utilisation of deoxycytidine for DNA and membrane synthesis in immature B lymphocytes draws the attention to its function in early events of lymphocyte maturation.

Antigens, Differentiation↗
PubMed1988

5-fluorodeoxyuridine decreases the effect of arabinofuranosyl-cytosine in undifferentiated human B lymphocytes.

An activated lymphocyte population was isolated from tonsils of 3-6 years old children by density gradient centrifugation. The isolated light density (LD) cells were bearing early B lymphocyte markers and were 5-6 times more active in DNA synthesis than the high density (HD) lymphocytes. It was found that about 70% of CdR was deaminated and converted into dTMP. The cells were very sensitive to araC, but the incorporation of [14C] CdR was twice more sensitive to araC than that of [5-3H]CdR. This effect can be explained by the interconversion of araC into araT nucleotide via the CdR interconversion pathway. This suggestion was also supported by the effect of 5-F-UdR, which decreased the inhibition of DNA synthesis caused by araC. 5-FUdR the inhibitor of thymidylate synthase, possibly decreases the interconversion of araC into araTTP, and its action via a smaller dTTP pool of the cells. Our data suggest, that the sensitivity of cells to araC may depend on the capacity of the CdR----TdR interconversion pathway, which, however, changes during the normal differentiation process of lymphocytes. Thus, the sensitivity of different malignant cells to araC is determined by the differentiation stage at which they were arrested during cell transformation.

B-Lymphocytes↗
PubMed1988

Phenotypic characteristics of three human non-Hodgkin lymphoma lines: flow cytometric analysis after long-term maintenance.

Three human non-Hodgkin lymphomas of B-cell origin have been maintained as xenografts in artificially immunosuppressed mice. The long-term maintenance (3-5 years) resulted in no significant change in the morphology, DNA-index or cell surface markers of the tumors. Immunophenotyping revealed many similarities in the morphologically distinct lines. Light chain (lambda) restriction appeared in two lines (HT 58 and 130), but in the third line (HT 117) the co-expression of both light chains indicated the origin from light chain 'uncommitted' B cells. HT 117 was also different, expressing high transferrin-receptor activity, although it proliferates with practically the same rate as the other two lines. This study confirms the value of the xenograft system to approaching many tumor-specific problems.

Animals↗
PubMed1987

Heterogeneity of human natural killer cells with respect to lectin-binding ability.

The binding ability of peanut agglutinin (PNA), lentil agglutinin (LEN), soybean agglutinin (SBA), wheat germ agglutinin (WGA), and asparagus pea agglutinin (ASP) to human natural killer (NK) cells with the use of the double-marker immunofluorescence technique was studied. For identification of NK cells, VEP 13 (DC 16) monoclonal antibody was used. The receptor for PNA lectin was shown exclusively after neuraminidase treatment of cells, and VEP 13 antigen was neuraminidase resistant. The majority of VEP 13+ cells showed coexpression of lectin receptors for PNA, LEN, and WGA. Our results suggested that VEP 13 antigen and PNA receptor are two distinct membrane structures, whereas there is some competitive binding between LEN as well as WGA lectin and VEP 13 antibody. In double-marker experiments using PNA and LEN lectin, the small fraction of VEP 13+ cells lacking receptors for these lectins was found. In spite of neuraminidase treatment of the cells, no binding of SBA and ASP was shown. These results indicated apparent heterogeneity of NK cells with respect to lectin receptor expression. WGA lectin, which bound to all VEP 13+ cells, could probably be useful for isolation of NK cells.

Antibodies, Monoclonal↗
PubMed1986

Regulatory function of cell surface molecules CD2-, LFA- and beta 2-microglobulin in natural killer cell activity.

The functional importance of various cell membrane bound molecules was studied and compared in the NK cytotoxicity and CTL activity. LFA-1 and CD2 participate in both killing functions, while CD3 and CD8/CD4 as well as MHC class I molecules are involved only in CTL activity. Nevertheless CD2- and beta 2-microglobulin are representatives of the NK function. It was demonstrated that CD2-, LFA-1 and beta 2-microglobulin molecules have an additive and complementary function in the killing mechanism. The upregulation of alpha- and gamma-interferons on NK function seems not to be a consequence of the enhanced expression of these molecules on the cell surface induced by IF at the same time.

Antibodies, Monoclonal↗
PubMed1986

Lectin-dependent cell-mediated cytotoxicity and blastogenesis by large granular-enriched and depleted lymphocytes.

The role of larger granular-enriched and depleted lymphocytes was studied in lectin-dependent cell-mediated cytotoxicity (LDCC) against adherent HEp-2 human epipharynx carcinoma target cells. LDCC was evaluated by detachment from the monolayer of 3H-thymidine-prelabelled HEp-2 cells in a 24 h assay at effector-target cell ratios of 25:1 and 50:1 in the presence of 25 micrograms/ml concanavalin A (Con A). Under the aforementioned conditions but in the absence of Con A natural cell-mediated cytotoxicity (NCMC) was not found. However, cytotoxicity was significantly augmented in the presence of Con A (= LDCC) using human peripheral blood mononuclear cells (PBMC) as effectors. Large granular lymphocytes (LGL), which show high natural killer (NK) activity to K 562 target cells, failed to be cytotoxic against HEp-2 targets similar to large granular depleted lymphocytes (LGL-DL). On the other hand, LGL caused only a slight LDCC; whilst LGL-DL induced strong LDCC activity towards HEp-2 targets. In comparison to LDCC using LGL-DL as effector cells, LGL and LGL-DL mixed at a ratio of 1:2, and added to target cells, had no major effect on LDCC, while a lower level of LDCC was observed at LGL/LGL-DL ratios of 1:1, and 2:1, suggesting the dilution of LGL-DL, potential effectors of LDCC to HEp-2 cells, rather than a specific regulatory role of LGL in LDCC. In parallel studies, the proliferation of LGL-DL in response to Con A was less than that observed with PBMC or LGL. The response could be restored by replacing half of LGL-DL per culture with an equal number of LGL, or by the addition of 10% monocytes. Significant functional differences between LGL and LGL-DL in LDCC as well as in Con A-induced blastogenesis are suggested.

Cell Line↗