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Biomedical subjects

H Ben-Bassat

Publications and source records attributed to H Ben-Bassat.

At least 91 records · Page 5Linked to original sources
PubMed1977

Fluidity of membrane lipids and lateral mobility of concanavalin A receptors in the cell surface of normal lymphocytes and lymphocytes from patients with malignant lymphomas and leukemias.

Lymphocytes isolated from the peripheral blood of patients with nonmalignant and malignant disorders were studied for fluidity of membrane lipids and lateral mobility of concanavalin A (Con A) receptors. The degree of fluidity of the surface membrane lipid core was monitored quantitatively by fluorescence polarization analysis using the probe 1,6-diphenyl-1,3,5-hexatriene embedded in lipid regions of the surface membrane of intact cells. Mobility of Con A surface receptors was determined by the cap-forming ability after binding of fluorescent Con A. The present studies were performed on lymphocytes from 28 patients with malignant lymphomas, 22 patients with leukemia, 28 individuals who either were healthy or had nonmalignant disorders, and 5 patients with carcinoma. The results showed that lymphocytes and mononuclear cells from patients with malignant lymphomas and leukemias have a more fluid lipid layer in their surface membrane than do lymphocytes obtained from healthy individuals or from patients with other malignant and nonmalignant disorders. This increase in membrane fluidity was less pronounced in lymphocytes isolated from leukemic patients in clinical remission and from leukemic patients receiving treatment with steroids. The results also show a marked difference in the cap-forming ability of lymphocytes from patients with malignant lymphomas or leukemia as compared with lymphocytes from patients with non-malignant disorders or carcinoma. Lymphocytes isolated from lymphoma and chronic lymphatic leukemia patients during remission stages of the disease exhibited a higher cap-forming ability. The cap-forming ability of cells from patients with chronic lymphocytic leukemia was unaffected by treatment with steroids. The present results, which are in line with previous observations, have shown that normal lymphocytes can be characterized by a low degree of lipid fluidity but a high degree of mobility of Con A receptors, whereas leukemic lymphocytes are characterized by a high degree of lipid fluidity but a low degree of mobility of Con A receptors. These results confirmed our general hypothesis on the dynamic interrelation between membrane lipids and membrane protein receptors, and they indicate that the widely accepted term "membrane fluidity" requires better consideration for different membrane components.

Carcinoma↗
PubMed1976

Properties of the K562 cell line, derived from a patient with chronic myeloid leukemia.

The K562 cell line derived from a CML patient in blast crisis was examined for properties of B and T lymphocytes and cell lines. K562 lacks the B markers of immunoglobulins, Epstein-Barr virus (EBV) genome and associated nuclear antigen, and receptors for EBV. A low proportion of cells from rosettes with sheep erythrocytes, the frequency of which is considerably increased after neuraminidase treatment. Unlike B lines but like T lines, K562 cells are lysed rapidly by C'/Fc receptor-positive human blood leukocytes and do not stimulate MLC reactions. On the other hand, K562 lacks T antigen, high radiosensitivity and sensitivity to growth inhibition by thymidine. The cells do not contain N-APase, an enzyme found in all lines derived from lymphoid cells and in lymphoproliferative diseases. By scanning electron microscopy, K562 cells were seen to be rounded and relatively smooth, with small numbers of short microvilli resembling undifferentiated leukemic cells. A few cells had narrow ridge-like profiles and small ruffles similar to granulocytic leukemic cells. K562 is strongly positive for immunoglobuln Fc receptors and pinocytosis, but does not phagocytose or mediate antibody-dependent phagocytosis or cytolysis. Among histochemical stains, K562 is positive for esterase, lipid, and acid phosphatase. There seems to be no doubt that K562 is not a B cell line. While it has some T cell properties, these are not exclusive. Some of its characteristics indicate that it is probably not lymphoid. Due to its low level of differentiation, its nature cannot be stated with certainty. On the basis of the possible presence of the cellular marker of chronic myeloid leukemia, the Ph chromosome, it may be regarded as belonging to the granulocytic series of cells.

Alkaline Phosphatase↗
PubMed1976

Fluidity difference in the surface membrane lipid core of human lymphoblastoid and lymphoma cell lines.

Twenty-five human hematopoietic cell lines established from patients with malignant and non-malignant diseases have been studied for membrane fluidity. The degree of fluidity in the surface membranes was quantitatively monitored by fluorescence polarization analysis of the fluorescence probe, 1,6-diphenyl 1,3,5-hexatriene, when embedded in the lipid region of the surface membrane of intact cells. The results have shown that cells derived from malignant diseases have a more fluid lipid layer in their surface membrane than cells derived from non-malignant disorders. It is, therefore, suggested that a quantitative analysis of fluidity differences in the cell surface membrane lipid core can be of value to the studies on basic differences between normal and malignant cell lines established from the human hematopoietic system.

Burkitt Lymphoma↗
PubMed1976

Concanavalin A receptors on the surface membrane of lymphocytes from patients with African Burkitt's lymphoma and lymphoma cell lines.

Lymphocytes isolated from the peripheral blood and from tumor tissues of patients with African Burkitt's lymphoma have been studied for cap formation and agglutinability by Concanavalin A (Con A). Peripheral blood from healthy adult persons served as a normal control and blood from patients with carcinoma served as a non-lymphoma control. These studies included 29 patients with Burkitt's lymphoma, 93 with carcinoma, and 105 healthy adult persons, as well as tumor tissues from 13 patients with Burkitt's lymphoma. The great majority of the carcinomas were from the face and neck regions. Lymphocytes from the blood of the majority of patients with Burkitt's lymphoma, as well as those from tumor tissues, exhibited a reduced cap-forming ability (2-6%) and increased Con-A-induced agglutinability compared to lymphocytes from healthy normal donors and from patients with carcinoma, although some of the lymphocytes from patients with carcinoma had a somewhat lower range of cap formation than the lymphocytes from healthy donors. No difference was observed in the interaction with Con A of lymphocytes from the different types of carcinoma studied. Eight lymphoid cell lines were established in our laboratory from the tumor tissues of patients with Burkitt's lymphoma. The cap-forming ability and agglutinability by Con A of these lines was examined and compared to those of the "classical" lymphoma lines: Raji, Daudi and P3HR1. All cell lines exhibited an increased Con-A-induced agglutinability and a reduced cap-forming ability compared to normal lymphocytes, except for P3HR1 cells which exhibited a cap-forming ability of 15-20%. These findings are discussed in relation to the association of the lymphocytes with malignancy and as a possible aid in the differential diagnosis between malignant lymphomas and other diseases.

Agglutination↗
PubMed1976

Comparative study of alkaline phosphatase activity in lymphocytes, mitogen-induced blasts, lymphoblastoid cell lines, acute myeloid leukemia, and chronic lymphatic leukemia cells.

Alkaline phosphatase [orthophosphoricmonoester phosphohydrolase (alkaline pH optimum), EC 3.1.3.1] purified from a Burkitt lymphoma cell line (Daudi) and Moloney-virus-induced murine leukemia (YAC) showed unique catalytic properties in substrate specificity and inhibition by cysteamine-S-phosphate. It migrated on polyacrylamide gel electrophoresis in a single activity band. Alkaline phosphatase with similar properties was found in several human lymphoblastoid cell lines, in chronic lymphatic leukemic cells, in organs of leukemic mice, and in sera of patients with certain lymphoproliferative disorders.

Alkaline Phosphatase↗
PubMed1975

Concanavalin A receptors on the surface membrane of lymphocytes from patient's with Hodgkin's disease and other malignant lymphomas.

Concanavalin A (Con A) induces movement of its receptors on the cell surface membrane. This induction results in a concentration of Con A site complexes on one pole of the cell to form a cap. A marked difference was found in the mobility of Con A receptor between lymphocytes from normal persons and lymphocytes from patients with Hodgkin's disease and other malignant lymphomas. Lymphocytes isolated from tonsils of patients undergoing tonsillectomy and from axillary lymph nodes of breast cancer patients exhibited approximately 30% of cells with caps, which is identical with the cap formation ability of normal lymphocytes. In biopsy material from patients with Hodgkin's disease and other malignant lymphomas, a significant decrease in the ability of the lymphocytes to form caps was observed. This difference in the mobility of Con A sites was even more pronounced in lymphocytes isolated from the peripheral blood. In 123 patients with Hodgkin's disease and other malignant lymphomas, cap formation ranged between 3 and 12%. The ability of cells, from a normal donor or a lymphoma patient, to form caps was independent of the source from which the lymphocytes were isolated, e.g., lymph node, spleen, or blood. Lymphocytes from patients with lymphoma were also agglutinated by Con A to a higher degree than normal lymphocytes. These findings are discussed in relation to the association of the lymphocytes with these malignancies and as a possible aid in their differential diagnosis.

Agglutination↗
PubMed1973

Mobility of carbohydrate-containing structures on the surface membrane and the normal differentiation of myeloid leukemic cells to macrophages and granulocytes.

Clones (D(+)) of a cultured line of myeloid leukemic cells can be induced to undergo normal differentiation to mature macrophages and granulocytes. There are also clones derived from the same cell line (D(-)) that could not be induced to differentiate. The carbohydrate-binding protein concanavalin A was used as a probe to study the mobility of carbohydrate-containing sites on the surface membrane of these cells. Changes in the distribution of concanavalin A binding sites on the surface membrane can be induced by concanavalin A. With the appropriate site mobility, this induction of a new distribution resulted in a concentration of concanavalin A-membrane site complexes on one pole of the cell to form a cap. D(+) and D(-) clones showed 50 and 5% of cells with caps, respectively, although both types of cells bound a similar number of concanavalin A molecules. Treatment of cells with trypsin increased cap formation from 5 to 40% in D(-) cells, but did not change the percentage of cells with caps in D(+) cells. The results show a difference in the mobility of concanavalin A binding sites in these two types of cells and suggest a difference in the fluid state of these carbohydrate-containing structures on the surface membrane. It is suggested that a gain of the ability of myeloid leukemic cells to undergo normal differentiation is associated with an increase in the fluidity of structures on the surface membrane where the concanavalin A sites are located. Differences in fluidity of specific membrane sites may also explain differences in the response of cells to other differentiation-inducing stimuli.

Agglutination↗