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Biomedical subjects

W Leibold

Publications and source records attributed to W Leibold.

At least 109 records · Page 6Linked to original sources
PubMed1977

Reactivity of alloantibodies of the Merrit B-cell system with leukemic cells and lymphoblastoid cell lines.

Twenty lymphoblastoid cell lines were typed with 38 antisera defining the 13 groups of the Merrit B-cell alloantigenic system, and results were compared with those of a 20-member CLL cell panel. While overall pattern of Merrit groups for the two types of cell population was similar, some sera in a number of groups showed unexpected negative cytotoxic reactions with lymphoid cells compared to other sera of the same group. However, in a number of instances, these negatively reacting cells could still specificity absorb out tb Merrit antibodies, suggesting that lymphoblastoid lines may show a higher incidence of the CYNAP (cytotoxicity-negative-absorption-positive) phenomenon than CLL cells. Twelve of the lymphoblastoid lines were HLA-D homozygous and in addition, each cell line displayed positive reactions for no more than 2 of the 13 Merrit groups, while 4 of the 8 heterozygous lines were positive for 3 of the 13 groups. These findings indicate that HLA-D-homozygous cell lines are antigenically simpler than the heterozygous lines for the Merrit system and suggest that HLA-D-homozygosity may correlate with homozygosity for at least one of the Merrit loci.

B-Lymphocytes↗
PubMed1977

Simplification of B-cell antisera of the Merrit system with platelets and lymphoblastoid cell lines.

Human sera with anti-HLA and anti-Merrit B-cell reactivities were absorbed with different volumes of a pool of packed outdated human platelets obtained from 237 donors. After absorption, each serum was tested against a panel of CLL cells and normal unfractionated peripheral blood lymphocytes that had given positive reactions with the same serum prior to absorption. The optimal platelet volume for complete absorption of anti-HLA and full preservation of anti-Merrit B-cell activities in these sera was found to be 1/10 to 1/5 of the volume of serum. Higher volumes of packed platelets, especially over 1/1, in most instances reduced anti-B-cell activity "nonspecifically." Among the platelet absorbed sera, those showing no HLA and strong anti-Merrit B-cell cytotoxicity were used for cross-absorption studies with cultured human lymphoid cell lines. Multi-specific anti-Merrit sera could be simplified by this method. Cultured lymphoblastoid cell lines represent a valuable resource, since large volumes of cells may be needed for absorption and simplification of human sera containing allogeneic B-lymphocyte antibodies.

B-Lymphocytes↗
PubMed1976

Tumorigenicity of Epstein-Barr virus (EBV)-transformed lymphoid line cells in autologous squirrel monkeys.

Eight squirrel monkeys (Saimiri sciureus) challenged with EBV or EBV-transformed SLCL were naturally or experimentally infected with Plasmodium knowlesi or Pl. brasilianum. Most of the animals had been splenectomized and unilaterally nephrectomized. Three of these monkeys received one dose of 6 to 12 X 10(8) autologous SLCL. These lines were derived from saimiri lymphoid cells permanently transformed by B-EBV in vitro. All three animals developed multiple undifferentiated malignant lymphomas and died 8 to 10 days post inoculation. Necropsy tumor specimens were EBNA-positive and contained 7 to 21 EBV genome equivalents per cell. EBNA- and EA-positive SLCL were established in vitro from four tumor explants of two monkeys. These results demonstrate that in vitro EBV-transformed SLCL are able to cause tumor formation in autologous squirrel monkeys. Five monkeys received high transforming doses of B-EBV or S-EBV, derived from one of the tumorigenic SLCL. None of the animals developed any sign of tumor formation during an observation period of up to 130 days. Three of these monkeys showed no detectable EBV-related seroconversion while the sera of two monkeys had become anti-EBNA-positive when tested at days 28 and 130 respectively post inoculation. Two additional monkeys received neither EBV nor SLCL. They showed no clinical evidence of tumor development or spontaneous seroconversion over a period of more than 1 year.

Animals↗
PubMed1976

Insolubilization of protein antigens on polyacrylic plastic beads using poly-L-lysine.

A new model system for quantitation of immunofluorescence on single cells is described using poly-L-lysine (PLL) coated polyacrylic plastic beads of approximately cell sizes as carriers for protein antigen. By increasing PLL concentration on the beads increased amounts of 125I labeled antigen were attached to the particles. Excess binding sites of PLL could be completely blocked by unrelated proteins. After staining with FITC-conjugated antibodies and quantitative fluorescence measurements of individual beads using a microspectrofluorimeter, strong correlations were found between antibody and antigen concentration on the beads. Neither repeated washings with PBS nor storage of the beads for two months caused detectable shedding of antigen-antibody complexes. There was a strong linear correlation between fluorescence intensity and the volume of beads, but the correlation between surface area and fluorescence was nonlinear. The described procedure was shown to be a simple method for quantitative and stable coating of particles with proteins. It can be applied as a useful model system for quantitative immunofluorescence studies on intracellular antigens.

Acrylamides↗
PubMed1976

Analysis of cell-surface markers with staphylococcal protein A: fluorescence studies on mammalian lymphoid determinants.

Membrane antigens including different classes of immunoglobulins, transplantation antigens, beta2-microglobulin, T lymphocyte specific antigens, and virally determined surface components were investigated using fluorescein-labeled Staphylococcal protein A in combination with cytofluorometric studies. Lymphocytes of seven species: mouse, rat, guinea pig, pig, cow, monkey, and human, and of ten human lymphoma-derived lines were tested. Analysis of the differential expression of surface markers revealed a reproducible reaction of protein A with cell-surface Fc of IgG actively produced by lymphoid cells from human, monkey, guinea pig, and pig, and with passively attached IgG molecules in the form of antibodies, directed against cell surface antigens of all lymphoid cells tested. No surface Ig was detected on so-called T lymphocytes. The distribution of cell-bound Ig density among surface Ig-positive cells was found to be different depending upon the origin of the cells with regard to lymphoid organ; it was parallel among the lymphoma lines tested and on peripheral blood cells from human, monkey, and pig, although large variations in fluorescence intensity among individual cells and among the different lines were recorded. Beta2-microglobulin determinants were found equally well on enriched human T and B cells. Transplantation, and T lymphocyte-specific antigens were detected on the majority of the lymphoid cells and on a restricted population respectively.

Animals↗
PubMed1976

Epstein-Barr virus interactions with human lymphocyte subpopulations: virus adsorption, kinetics of expression of Epstein-Barr virus-associated nuclear antigen, and lymphocyte transformation.

In order to further understand Epstein-Barr virus (EBV)-lymphocyte interactions, we investigated a chain of events including: (i) EBV binding to human lymphocyte subpopulations; (ii) the earliest appearance of EBV-determined nuclear antigen (EBNA) in the lymphocytes after EBV infection; and (iii) establishment of continuous lymphoblastoid cell lines (LCL) by infecting with EBV different types of lymphocyte preparations from the same as well as from different donors. By using direct membrane immunofluorescence assay, we found that only a small fraction of human peripheral blood and cord blood lymphocytes (CBL), and possibly less than 31% of the T cell-depleted lymphocyte population, carry receptors for P3HR-1 strain of EBV. The number of cells carrying receptors for EBV did not vary considerably among different blood lymphocyte populations from several normal donors. EBV adsorption on lymphocyte subpopulations showed that purified thymus-dependent (T) cells and thymocytes did not adsorb EBV, in contrast to T cell-depleted lymphocyte populations and lymphoid cells from fetal liver and spleen. In CBL infected with EBV strain B95-8, EBNA was detected by anti-complement immunofluorescence as early as 18 h after infection. This indicates that EBNA is the earliest detectable EBV-determined intracellular antigen to appear after infection and before or during lymphocyte transformation by EBV. Transformation was observed only in lymphocyte cultures containing detectable thymus-independent B cells but not in cultures of purified T cells. With one exception (es-b-1), all the EBV-transformed LCL from different origins carried surface-bound immunoglobulins (a B cell marker). These included also the 10 LCL obtained by infecting cultures of adherent cells from different donors. With regard to its surface markers, ES-B-1 appeared to be an exceptional EBV genome-carrying line, and it also lacked the ability to form spontaneous rosettes with sheep erythrocytes (a T cell marker). Therefore, it is possible that ES-B-1 was derived from an atypical B cell or B cell precursor or from a so-called "null cell" transformed by EBV.

Adsorption↗
PubMed1975

Induction of Epstein-Barr virus-associated nuclear antigen during in vitro transformation of human lymphoid cells.

Human lymphoid cells isolated from the peripheral blood of adults, from cord blood, and from fetal liver, spleen, bone marrow, and thymus were cultivated with or without a cell-free preparation of Epstein-Barr virus (EBV) with demonstrated transforming activity. The cultures were examined for the EBV-associated nuclear antigen (EBNA) and for transfromation into permanent lymphoblastoid cell lines (LCL). EBNA, seen only in cultures that had received exogenous EBV, was detected between days 1 and 6 after addition of EBV, most frequently on day 3. EBNA-positive cells had a lymphoblastoid appearance. Transformation into established LCL became apparent between days 12 and 19. The addition of pokeweed mitogen to cultures containing EBV enhanced the development of EBNA, whereas phytohemagglutinin or concanavalin A had no such effect. Neither EBNA nor transfomration was observed in lymphoid cells from fetal thymus. In fetal spleen, bone marrow, and liver cells, EBV regularly induced EBNA and LCL transformation.

Antigens, Viral↗
PubMed1975

Stimulation of normal lymphocytes with autologous lymphoid cell lines: properties of derived killer cells.

Lymphocytes from normal adults, with or without serological signs of previous Epstein-Barr virus (EBV) infection, could be stimulated to proliferate and produce killer cells by incubation with autologous EBV-genome-positive lymphoid cell lines (LCLs). The stimulated cells were most probably of T-cell origin, although at the peak of stimulation many of them lacked the sheep erythrocyte marker. Direct effector-target cell contact was necessary for lysis to occur. The cytotoxicity of autologously stimulated (AS) lymphocytes was not restricted to EBV-genome-positive LCLs, nor to cell lines of hematopoietic origin. It was equally broad if cells carrying complement receptor had been removed before stimulation. Fresh lymphocytes, blasts induced by phytohemagglutinin or concanavalin A, and Burkitt's lymphoma biopsy cells were resistant or considerably less sensitive. Mouse cells--even cell lines--were resistant. The sensitivity of target cells to lysis correlated positively with their capacity to block AS lymphocyte lysis of autologous LCLs in competition experiments. The cytotoxicity of AS lymphocytes was blocked by EBV-genome-positive and -negative cell lines, whereas the EBV-related cytotoxicity of T cells from acute cases of infectious mononucleosis was blocked by EBV-genome-positive LCL only.

Animals↗
PubMed1975

Possible use of established cell lines for MLR locus typing.

MLR histocompatibility typing was performed by in vitro stimulation of lymphocytes from various persons with fresh lymphocytes (irradiated) or with lymphoblostoid cell lines (mito-mycin-treated) derived from donors homozygous at the MLR locus. MLC responses to both types of stimulation correlated strongly suggesting that a) established lymphoblastoid line cells can express products of the MLR loc and b) fresh lymphocytes can be replaced by these long term lines in MLR typing. Two lines (LV-B and MS-B) derived from two MLR homozygous donors (lv and MS) were used throughout these experiments. It is possible that as additional lines are established from such MLR homozygous donors, a panel of typing cells could be created which would serve to standardize MLR typing and allow selection of unrelated but histocompatible donors for transplantation.

Cell Line↗
PubMed1975

Establishment and characterization of an Epstein-Barr virus (EBC)-negative lymphoblastoid B cell line (BJA-B) from an exceptional, EBV-genome-negative African Burkitt's lymphoma.

An Epstein-Barr virus (EBV)-negative lymphoblastoid cell line (LCL), BJA-B, was established from an African Burkitt's lymphoma (BL) which contained no detectable EBV DNA and did not express the EBV specified antigen EBNA, BJA-B cells grow in typically large, flat clumps. All carry surface-bound immunoglobulins, a B lymphocyte marker, and do not form rosettes with sheep erythrocytes. After infection of BJA-B cells by EBV the infected cells may produce either EBV-determined nuclear antigen (EBNA) or both EBNA and early antigen (EA), depending on the strain of EBV. The homogeneity of the BJA-B cell population with respect to immunological and isoenzyme markers and size suggests a clonal origin of the line. BJA-B is the first EBV-negative LCL established from an African Burkitt's lymphoma and demonstrates that an EBV-independent continuous B cell line can be established "in vitro" from other than leukemia or myeloma cells.

Antigens, Viral↗
PubMed1974

Continuous lymphoid cell lines with characteristics of B cells (bone-marrow-derived), lacking the Epstein-Barr virus genome and derived from three human lymphomas.

Three exceptional cell lines have been tested for the presence of the Epstein-Barr virus genome by nucleic acid hybridization (complementary RNA.DNA) and Epstein-Barr virus-determined nuclear antigen tests. Two lines were derived from Swedish lymphoma cases and one from an African Burkitt-like lymphoma biopsy that was negative for Epstein-Barr virus DNA and the virus-determined nuclear antigen. All three lines apparently lacked the viral genome. Two of the three lines clearly had characteristics of B-cells (bone-marrow-derived).

Antigens, Viral↗