| 1. |
- Malmström, P., et al.
(författare)
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Countercurrent Distribution of Lymphocytes from Human Peripheral Blood in an Aqueous Two-Phase System : I. Separation into Subsets of Lymphocytes Bearing Distinctive Markers’
- 1980
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Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 53, s. 39-50
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Tidskriftsartikel (refereegranskat)abstract
- Lymphocytes from human peripheral blood have been separated by countercurrent distribution in a charged aqueous two-phase system composed of Dextran T 500 and polyethylene glycol 6000 with a cell yield of 59–88% and viability above 90%. A highly reproducible partition pattern was seen with four distinct peaks. Lymphocytes with surface membrane immunoglobulin (SmIg) were located in the first part of the distribution corresponding mainly to peak I. T lymphocytes as detected by E rosetting and α-naphthyl acetate esterase (ANAE) staining showed a broad distribution with a maximum in peaks II and III. ANAE-negative lymphocytes were seen in both extremes of the distribution, corresponding to B cells in the first part and to a population of E− and SmIg− lymphocytes in the last part. Monocytes were present in all fractions with some enrichment in peaks II–IV. Lymphocytes with low-affinity Fc receptors were found in B-cell-containing fractions in the first part of the distribution, but also in the last part. Lymphocytes with high-affinity Fc receptors were detected mainly in peak IV. It is thus demonstrated that peripheral blood lymphocytes can be fractionated into subpopulations enriched in cells with characteristic markers.markers.
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| 2. |
- Malmström, P, et al.
(författare)
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Countercurrent distribution of lymphocytes from human peripheral blood in an aqueous two-phase system. : II. Separation into subsets of lymphocytes with distinctive functions
- 1980
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Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 53, s. 51-64
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Tidskriftsartikel (refereegranskat)abstract
- Lymphocytes from human peripheral blood were separated by Countercurrent distribution (CCD) in a charged aqueous two-phase system composed of Dextran T 500 and polyethylene glycol 6000. Maximal responses to the T-cell mitogens phytohemagglutinin and concanavalin A were detected in a part of the distribution corresponding to the area where the highest percentage of E rosetting cells were seen. Antibody-dependent cellular cytotoxicity was mediated by lymphocytes located in a restricted part of the distribution separate from the majority of T lymphocytes. Lymphocytes with natural killer activity against K 562, adherent melanoma cells, and fibroblasts were detected in the same region. This area of the distribution also contained the peak of lymphocytes with high-affinity Fc receptors. It was further investigated whether affinity separation may be possible in two-phase systems on the basis of cell to cell interaction. Affinity CCD utilizing the interaction between sheep erythrocytes (SRBC) and T lymphocytes was shown to redistribute the majority of T cells into the area in which SRBC were located, while other lymphocytes were not affected. Lymphocytes mediating natural killing to adherent target cells were not redistributed, indicating that they lack high-affinity receptors for SRBC.
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| 3. |
- Miörner, Håkan, et al.
(författare)
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Regulation of mitogen-induced lymphocyte DNA synthesis by human interferon of different origins
- 1978
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Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 35:1, s. 15-24
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Tidskriftsartikel (refereegranskat)abstract
- Human fibroblast and leukocyte interferons were found to suppress lymphocyte mitogenesis induced by optimal doses of phytohemagglutinin and concanavalin A. In certain situations (low doses of mitogen and/or low doses of interferon), however, interferon significantly enhanced mitogenesis. In experiments using varying concentrations of interferon, dose-response curves with different slopes were obtained for fibroblast and leukocyte interferons. The effect of interferon was apparently exerted during early stages of the lymphocyte cell cycle. There was no inhibitory effect of interferon if the lymphocytes were washed with medium before being exposed to mitogen. Interferon increased the binding of radiolabeled mitogens to cells. The results suggest that the immunological effects of interferon are consequences of actions on lymphoid cells. Fibroblast and leukocyte interferons seem to have different modes of action, or to bind differently to target cells. Possible mechanisms for the suppressive and enhancing effects of interferons on lymphoid cells are discussed.
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| 4. |
- Nelson, K, et al.
(författare)
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Separation of rat leukocytes by countercurrent distribution in aqueous two-phase systems. II. Subpopulations which mediate selective and nonselective lysis of normal and colon carcinoma target cells in vitro
- 1978
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Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 37:2, s. 422-431
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Tidskriftsartikel (refereegranskat)abstract
- Spleen cells from WF rats immunized to allogeneic lymphoid cells or to syngeneic colon carcinomas and from unimmunized controls were separated by countercurrent distribution in aqueous two-phase systems. The cells were assayed for cytotoxicity to allogeneic fibroblasts or syngeneic colon carcinoma cells and to syngeneic fibroblasts in a 24-hr 51Cr-release assay. Cells from immunized rats which selectively lysed the specific target cells were repeatedly found in one area of the distribution separate from the majority of cells, which nonselectively lysed syngeneic fibroblasts as well. A similar subpopulation which nonselectively lysed all target cells assayed was recovered from the spleens of unimmunized rats. The cells were also assayed for the ability to lyse antibody-coated thymocytes in a 4-hr 51Cr-release assay. The peak of K cells was found to overlap partially that of cells with nonselective cytotoxicity.
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| 5. |
- Ramos, O F, et al.
(författare)
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Elevated NK-mediated lysis of Raji and Daudi cells carrying fixed iC3b fragments
- 1989
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Ingår i: Cellular Immunology. - 0008-8749 .- 1090-2163. ; 119:2, s. 459-469
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Tidskriftsartikel (refereegranskat)abstract
- Raji and Daudi cells were opsonized with C3b, iC3b and C3d fragments by using purified complement components. The sensitivity of C3-opsonized cells to lysis mediated by low density blood lymphocytes was studied. Raji and Daudi cells carrying C3b or C3d fragments were lysed with similar efficiencies as the nonopsonized cells. The presence of iC3b on the target surface imposed elevated NK sensitivity. The iC3b-mediated enhancement of NK lysis was inhibited when iC3b fragments or rabbit anti-human C3 antibodies were included into the lytic assays. These results indicate that the iC3b fragments fixed on the targets bind to the CR3 on the lymphocytes. Results obtained in immobilized conjugate-lytic assays showed that iC3b-opsonized targets interact more readily with the lymphocytes. This was reflected by the elevated proportion of lymphocytes that were bound to the iC3b-carrying targets. The proportions of conjugates in which target damage occurred were similar with the control and with the iC3b-carrying cells. It seems therefore that opsonization of targets with iC3b leads to recruitment of effector lymphocytes due to contact with their CR3. However, once the effector-target contact is established, the triggering of lytic function does not seem to be influenced by the iC3b/CR3 bridge.
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| 6. |
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| 7. |
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| 8. |
- Andersson, Eva, et al.
(författare)
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CD4+CD57+ T cells derived from peripheral blood do not support immunoglobulin production by B cells
- 1995
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Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 163:2, s. 245-253
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Tidskriftsartikel (refereegranskat)abstract
- A small subpopulation of CD4+ T cells found in peripheral blood coexpresses the CD57+ marker normally found on, e.g., NK cells. It is known that this population occurs in a higher frequency in certain diseases. The same antigen has also been shown to be expressed on CD4+ T cells derived from germinal centers. The localization of this cell population to specialized lymphoid structures suggests that it may play a role in the evolution of the antibody response following antigenic stimulation in vivo. We have examined the ability of peripheral blood helper T cells coexpressing CD57 to participate in B cell activation/differentiation and evaluated their responses to polyclonal stimulation. The CD4+CD57+ T cells do not express mRNA for a number of different cytokines or for the CD40 ligand after activation in vitro. Furthermore these cells do not induce differentiation of B cells into immunoglobulin-producing cells. Consequently, despite their CD4 phenotype and their ability to be activated, to express the IL-2 receptor, and to enter into the cell cycle, they do not act as T helper cells under conditions where CD4+/CD57- cells normally do so. The findings suggest that this peripheral blood helper T cell population is functionally different from regular CD4+ T cells. The basis for the lack of proper costimulatory signals for immunoglobulin production might be related to the low expression of CD28.
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| 9. |
- Andersson, Eva, et al.
(författare)
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Immunoglobulin production induced by CD57+ GC-derived helper T cells in vitro requires addition of exogenous IL-2
- 1996
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Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 169:2, s. 166-173
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Tidskriftsartikel (refereegranskat)abstract
- Germinal centers (GC) are well-defined areas in lymphoid organs were B cells proliferate and differentiate in response to T-cell-dependent antigens. The GC comprises B cells, follicular dendritic cells, tangible body macrophages, and a low number of CD4+ T cells. A large portion of these T cells expresses CD57. We have examined the ability of the CD4+CD57+ GC T cells to become activated and to take part in B cell activation processes, These T cells coexpress CD45RO, CD69, CD28, and upon mitogenic stimulation CD25, The cell population was found neither to containe nor to be able to produce any specific mRNA for IL-2, IL-4, and IFN-γ upon activation. Levels of mRNA encoding CD40 ligand was also undetectable under similar conditions. Furthermore, in contrast to ordinary CD4+ T cells, this population expressing CD57 was unable to induce B cells to Ig production in the presence of pokeweed mitogen or SEA unless IL-2 was added to the cultures, However, despite their apparent lack of function CD4+CD57+ GC T cells were found to rescue GC B cells from cell death in vitro to the same extent as CD4+CD57- T(h) cells, The phenotypical and functional differences found between these T cells and regular T(h)-cells suggest that they either represent a T cell subset with distinct properties within the GC yet to be determined or that they represent T cells, Irate in the immune response, having lost most of their original functions and capabilities.
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| 10. |
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