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Biomedical subjects

S O Sharrow

Publications and source records attributed to S O Sharrow.

At least 127 records · Page 7Linked to original sources
PubMed1981

Determination of surface antigens on highly purified human NK cells by flow cytometry with monoclonal antibodies.

We examined highly purified populations of NK cells, T cells, monocytes, and PMN with a variety of monoclonal reagents presumed specific for T cells and monocytes. The enriched NK cells showed a pattern of reactivity that was distinct from that of the other 3 populations, sharing antigens with T cells but also sharing antigens with monocytes and/or PMN. A portion of the enriched NK cells expressed OKT8, OKT10, and Lyt-3 antigens that were reported previously as T cell-associated antigens, but no reactivity was seen with other T cell-associated antigens (OKT3, OKT4, OKT6, and OKT11). In addition a portion of the enriched NK cells were positive for OKM1, asialo-GM1, and Ia antigens, which are undetectable on typical T cells but are present on PMN and/or monocytes. By depletion of antigen-positive cells on antibody monolayers, it was found that the activity of the enriched NK population was associated mainly with cells reactive with OKT10, OKM1, and Lyt-3. Although considerable evidence exists to support the T lineage of NK cells, the sharing of some antigens by NK cells and monocytes has suggested a possible relationship of NK cells to cells of the monocyte lineage. A possibility certainly exists that NK cells are not in either T cell or monocyte lineages and may represent a separate lineage of lymphoid cells.

Antibodies, Monoclonal↗
PubMed1980

Lysophosphatidylcholine in liposomal membranes: enhanced permeability but little effect on transfer of a water-soluble fluorescent marker into human lymphocytes.

In an attempt to enhance delivery of liposome contents into cells, we tested the effect of lysophosphatidylcholine on transfer of the fluorescent dye, carboxyfluorescein, from small unilamellar and large multilamellar vesicles to human lymphocytes. Dioleoyl phosphatidylcholine and dioleoyl phosphatidylcholine-lysophosphatidylcholine small unilamellar vesicles with varying lipid ratios were prepared and characterized. In the presence of lysophosphatidylcholine, small unilamellar vesicles were slightly smaller and more leaky than those made without lysophosphatidylcholine. Lysophosphatidylcholine induced less leakage in large multilamellar vesicles. It did not show any appreciable effect on transfer of liposome contents, whether included as part of the liposomal bilayer (of unilamellar or multilamellar vesicles) or added exogenously together with small unilamellar dioleoyl phosphatidylcholine vesicles.

Cell Membrane Permeability↗
PubMed1980

Phenotypic expression of I-A and I-E/C subregion determinants on murine thymocytes.

The expression of Ia antigens on murine thymocytes has been assessed by indirect immunofluorescence and flow microfluorometry analysis. Antisera specific for I-region determinants were found to react with at least 50% of thymus cells in single-cell suspensions. When these antisera were tested on thymus cells of an appropriate recombinant strain, it was found that both I-A and I-E/C subregion determinants could be detected. Monoclonal antibodies to I-A and to I-E determinants also reacted with thymus cells in a similar fashion, eliminating the possibility that contaminating specificities accounted for the reactivity of alloantisera. The majority of Ia-positive thymus cells appeared to express determinants encoded by genes of both I-A and I-E/C subregions. Ia expression on individual thymocytes was also correlated with cell size as measured by forward light scatter intensity. However, unlike antigens detected by rabbit anti-mouse brain antisera, Ia antigens did not appear to be associated with known subpopulations of thymocytes distinguishable by light scatter intensity. The presence of I-region encoded antigens on thymocytes may play a role in maturation of T cells in the thymus microenvironment.

Animals↗
PubMed1980

Role of accessory cells in B cell activation. I. Macrophage presentation of TNP-Ficoll: evidence for macrophage-B cell interaction.

The importance of cell interaction for thymic independent antigen responses has not been widely appreciated. The present report demonstrates, however, that macrophage-B cell interaction may be an important feature of B ce-l activation for the response to at least one polysaccharide thymic independent antigen, TNP-Ficoll. Experiments were performed demonstrating that a strict accessory cell requirement exists for the thymic independent response to soluble TNP-Ficoll, and that such accessory cells are both adherent and phagocytic, that is, macrophages. It was further demonstrated that macrophages could be pulsed with TNP-Ficoll and that these pulsed macrophages could activate B cells to respond, but only if the pulsed macrophages were viable. Thus, one function that macrophages can fulfill in responses to TNP-Ficoll is the specific function of antigen presentation. Such presentation of TNP-Ficoll by macrophages to B cells suggests that the antigen may not be activating B cells directly, and raises the possibility that the interaction of B cells and macrophages might be genetically restricted.

Animals↗
PubMed1980

Differential binding of fluorescein-labeled lectins to mouse thymocytes: subsets revealed by flow microfluorometry.

Fluorescein-labeled lectins bound to mouse thymocytes were analyzed by flow microfluorometry. This technique has identified several lectins that bind differentially to thymocyte subsets. The most complex fluorescence distributions were obtained using lectins with nominal specificities for galactose or N-acetylglucosamine. Inhibition of binding by sugars confirmed that the fluoresceinated lectins were bound to cells at their carbohydrate binding site. Simultaneous analyses of lectin fluorescence and forward light scatter intensity showed that cell subpopulations of different sizes can exhibit marked differences in the level of binding such that the amount of lectin bound per cell is often independent of cell size. A minor population of dull or unstained cells, delineated by several of these lectins, correlates with the subpopulation of medium-sized thymocytes resistant to in vivo cortisone treatment.

Abrin↗
PubMed1980

HLA-DRw alloantigens can be detected on peripheral blood T lymphocytes.

Antisera detecting HLA-DRw antigens (human Ia-like) react in cytotoxicity assays with peripheral blood B cells and monocytes but not T lymphocytes. Antisera detecting DRw specificities were used in flow microfluorometry studies to determine whether T lymphocytes express these antigens in quantities not detected by cytotoxicity. Peripheral blood lymphocytes depleted of monocytes were incubated with DRw antisera, reacted with fluoresceinated goat anti-human IgG, and analyzed on the fluorescence-activated cell sorter (FACS). Anti-DRw sera were found to be reactive on all of the lymphocytes as evidenced by a positive fluorescence signal. The reactivity was specific in that only those sera that detected DRw antigens on B cells and monocytes were reactive with the total lymphocyte population from the same donor. Reactivity of the antisera was removed by absorbing the antiserum with monocyte/B cells and T cells from a donor with the same DRw antigen as that found on the target cell of the donor tested. The results demonstrate the presence of DRw antigens on resting peripheral blood T lymphocytes. The implications of quantitative differences in DRw antigen expression on lymphoid cells are discussed.

Absorption↗
PubMed1980

Ly 9, an alloantigenic marker of lymphocyte differentiation.

A new lymphocyte cell surface alloantigen, provisionally designated Ly 9, is detected by flow microfluorometry(FMF), as an extra specificity in sera from anti-Lyt immunizations. Ly 9.2, one of the allelic specificities, commonly is detected as a unique immunofluorescence profile of thymocytes with anti-Lyt 3.1 sera. The alternative antigenic specificity, Ly 9.1, can be detected routinely in antisera prepared against Lyt 2.1 and Lyt 3.2. This lymphocyte alloantigen has both a unique strain and cell/tissue distribution. Quantitative measurement of Ly 9 immunofluorescence by FMF on heterozygote cells shows that Ly 9 antigen expression is co-dominant and reduced in levels relative to parental homozygote cells. Ly 9 is expressed on all thymocytes, peripheral lymphocytes, and on a subpopulation of cells in the bone marrow. This antigen is not expressed to any significant degree on erythrocytes, epidermal cells, sperm, or in suspensions of testis, brain, kidney, liver, or lung. FMF analysis and absorption typing reveals a quantitatively lower level of antigen expression on thymocytes compared with spleen or lymph node cells. Cytotoxic elimination experiments confirm that Ly 9 is expressed on at least 2 different T cell functional subsets and B cells.

Animals↗
PubMed1979

Expression of xenotropic murine leukemia viruses as cell-surface gp70 in genetic crosses between strains DBA/2 and C57BL/6.

Flow microfluorometry was used to assess levels of xenotropic murine leukemia virus envelope-related cell-surface antigens (XenCSA) expressed on lymphocytes of mice derived from crosses between C57BL/6 (B6) and DBA/2 (D2); 24 recombinant inbred strains (BXD RIs) and 62 backcross mice were studied. The results suggest that XenCSA expression is affected by more than one gene but that the predominant influence is exerted by a single semidominant gene apparently located on chromosome 4 at or in close proximity to the Fv-1 locus. Studies of spontaneous virus production in B6D2F1 X D2 mice suggest that this locus may also affect production by spleen cells of xenotropic MuLV registering in a fluorescent antibody assay of mink lung cells.

Animals↗
PubMed1979

Phenotypic and functional effects of the motheaten gene on murine B and T lymphocytes.

Lymphoid cells from C57BL/6 mice homozygous for the me gene exhibit multiple phenotypic and functional abnormalities from early as one week of age. In the B cell population these include a reduction in the frequency of detectable surface Ig+ cells, alterations in the level of expression of surface IgM and IgD, an increase in the frequency of large cells, plasma cells and TNP-specific plaque forming cePS. Together these findings provide strong evidence for polyclonal activation of B cells. The high level of expression of xenotropic MuLV gp70 by me/me spleen and lymph node cells provides further evidence for lymphoid cell activation. In preliminary studies, me/me T cells appeared to be phenotypically and functionally less affected by the me gene. The distribution of Thy 1.2 on the surface of spleen and lymph node T cells varied from low to normal and the mitogenic responses to Con A and PHA were depressed. It remains to be determined what the basic deficiency in me/me mice is and whether it affects primarily B cells or all lymphoid cells.

Animals↗
PubMed1979

Variations in expression of xenotropic murine leukemia virus genomes in lymphoid tissues of NZB mice.

Lymphocytes from Thy, Sp, LN, and BM and NZB mice were tested for expression of X-MuLV genomes as cell surface gp70 (XenCSA) or infectious virus. The results demonstrate major dissociations for these parameters of X-MuLV expression in different lymphoid compartments and suggest that factors involved in T lymphocyte differentiation modify the levels of expression in these two modes.

Animals↗
PubMed1979

Binding of antigen-bearing fluorescent liposomes to the murine myeloma tumor MOPC 315.

Small unilamellar lipid vesicles bearing the DNP-hapten on their surfaces and containing the water-soluble fluorescent dye carboxyfluorescein were formed by sonication. These vesicles were incubated with cells from the murine myeloma tumor MOPC 315, which secrete and also bear on the cell surface an immunoglobulin with affinity for the nitrophenyl hapten. At 0 degrees C the cells bound an average of several thousand vesicles at saturation. This binding was specific for the nitrophenyl hapten on the vesicle since it was abolished by an excess of soluble nitrophenyl derivative, by omission of the hapten from the vesicle, or by substitution for MOPC 315 of a tumor lacking receptors for the nitrophenyl hapten. Specific binding of vesicles was greater when cells were incubated at 37 degrees C. The study suggests that ligand-bearing vesicles can be a useful marker for cell surface immunoglobulin. However, in spite of the ability to "target" vesicles to cell surface determinants, binding did not result in increased delivery of vesicle contents to the cytoplasm.

Animals↗
PubMed1979

Identification and separation of Thy-1 positive mouse spleen cells active in natural cytotoxicity and antibody-dependent cell-mediated cytotoxicity.

The expression of the Thy-1 antigen on mouse spleen cells responsible for NK activity and ADCC was investigated by using a monoclonal IgM anti-Thy-1.2 antibody. Both C-mediated cytotoxicity and the fluorescence-activated cell sorter were used to fractionate cells. The effector cells were found to be heterogeneous in their expression of Thy-1. Effector cells from nude BALB/c mice were predominantly Thy-1 positive; some of the NK cells in CBA spleens appeared to be Thy-1 positive, but at least one-third of the lytic activity was due to Thy-1 negative cells. The effects of treatments on NK cytotoxicity and ADCC were very similar, supporting the hypothesis that the same cells mediate both activities.

Animals↗
PubMed1978

Antibody-mediated targeting of liposomes. Binding to lymphocytes does not ensure incorporation of vesicle contents into the cells.

Small sonicated lipid vesicles containing the water-souble fluorescent dye 6-carboxyfluorescein were formed from dioleoyl phosphatidylcholine and the antigenic lipid N-dinitrophenylaminocaproyl phosphatidylethanolamine. When these vesicles were incubated with trinitrophenyl-modified human lymphocytes and divalent anti-trinitrophenyl antibody, the antibody bound 5000 to 15 000 vesicles to each cell. Binding was detected by fluorescence microscopy and quantitated by fluorometry and flow microfluorometry. Binding was three times greater with F(ab')2 fragments than with the whole antibody and, as expected, was almost absent with the monovalent F(ab') fragments. It was also absent or greatly reduced, (i) with control immunoglobulin G, (ii) in the presence of excess soluble trintrophenyl hapten, or (iii) if hapten was omitted from either cells or vesicles. It was unaffected by sodium azide and 2-deoxy-D-glucose but was markedly decreased at 3 degrees C. It was not reversed by incubation at 3 degrees C with excess trinitrophenyl lysine. Self-quenching of the fluorescence of 6-carboxyfluorescein was used to distinguish between release of vesicle contents into the cells and simple binding of intact vesicles (Weinstein, J.N., Yoshikami, S., Henkart, P., Blumenthal, R. and Gagins, W.A. (1977) Science 195, 489--491). Antibody-mediated binding led to little or no increase over spontaneous background levels in the amount of vesicle contents released into the lymphocytes.

Antibodies↗