scholarly journals Expression of c-myb and B-myb, but not A-myb, correlates with proliferation in human hematopoietic cells

Blood ◽  
1991 ◽  
Vol 77 (1) ◽  
pp. 149-158 ◽  
Author(s):  
J Golay ◽  
A Capucci ◽  
M Arsura ◽  
M Castellano ◽  
V Rizzo ◽  
...  
Keyword(s):  
B Cells ◽  
B Lymphocytes ◽  
Cellular Proliferation ◽  
Cell Types ◽  
T And B Lymphocytes ◽  
Thymidine Uptake ◽  
Mitogenic Stimulation ◽  
Myb Gene ◽  
Normal Human

The steady-state expression of three members of the myb family of genes, c-myb, B-myb, and A-myb, was studied in four purified normal human hematopoietic cell types, ie, T and B lymphocytes, monocytes, and granulocytes. The c-myb proto-oncogene is low to undetectable in resting T and B lymphocytes and shows a biphasic induction in both cell types after mitogenic stimulation, with a first peak at 3 hours and a second and stronger induction at 44 to 72 hours. Study of the B-myb gene showed that this gene is low to undetectable in resting T or B cells and is strongly induced after mitogenic stimulation with a peak between 44 and 72 hours in both cell types. Finally, the A-myb gene shows a pattern of expression in lymphocytes different from that of c- myb and B-myb. It is expressed in resting T lymphocytes and its levels gradually decrease after mitogenic stimulation to become undetectable at 48 hours. It is also expressed in a subpopulation of large B lymphocytes but not in in vitro activated B cells. Neither of the three members of the myb family of genes was expressed in monocytes and granulocytes, even after functional activation of these cells. Taken together, these data bring further evidence for the role of c-myb in cellular proliferation and on the basis of the kinetics of its induction relative to thymidine uptake, we hypothesize that it may have a role during G1 progression in addition to that already documented for entry into S phase. Furthermore, our studies indicate that another member of the myb family of genes, B-myb, may also be involved in cellular proliferation, because its expression correlates with the induction of mitogenesis.

scholarly journals Expression of c-myb and B-myb, but not A-myb, correlates with proliferation in human hematopoietic cells

Blood ◽  
1991 ◽  
Vol 77 (1) ◽  
pp. 149-158 ◽  
Author(s):  
J Golay ◽  
A Capucci ◽  
M Arsura ◽  
M Castellano ◽  
V Rizzo ◽  
...  
Keyword(s):  
B Cells ◽  
B Lymphocytes ◽  
Cellular Proliferation ◽  
Cell Types ◽  
T And B Lymphocytes ◽  
Thymidine Uptake ◽  
Mitogenic Stimulation ◽  
Myb Gene ◽  
Normal Human

Abstract The steady-state expression of three members of the myb family of genes, c-myb, B-myb, and A-myb, was studied in four purified normal human hematopoietic cell types, ie, T and B lymphocytes, monocytes, and granulocytes. The c-myb proto-oncogene is low to undetectable in resting T and B lymphocytes and shows a biphasic induction in both cell types after mitogenic stimulation, with a first peak at 3 hours and a second and stronger induction at 44 to 72 hours. Study of the B-myb gene showed that this gene is low to undetectable in resting T or B cells and is strongly induced after mitogenic stimulation with a peak between 44 and 72 hours in both cell types. Finally, the A-myb gene shows a pattern of expression in lymphocytes different from that of c- myb and B-myb. It is expressed in resting T lymphocytes and its levels gradually decrease after mitogenic stimulation to become undetectable at 48 hours. It is also expressed in a subpopulation of large B lymphocytes but not in in vitro activated B cells. Neither of the three members of the myb family of genes was expressed in monocytes and granulocytes, even after functional activation of these cells. Taken together, these data bring further evidence for the role of c-myb in cellular proliferation and on the basis of the kinetics of its induction relative to thymidine uptake, we hypothesize that it may have a role during G1 progression in addition to that already documented for entry into S phase. Furthermore, our studies indicate that another member of the myb family of genes, B-myb, may also be involved in cellular proliferation, because its expression correlates with the induction of mitogenesis.

scholarly journals Interleukin-13 in Combination With CD40 Ligand Potently Inhibits Apoptosis in Human B Lymphocytes: Upregulation of Bcl-xL and Mcl-1

Blood ◽  
1997 ◽  
Vol 89 (12) ◽  
pp. 4415-4424 ◽  
Author(s):  
Jon Lømo ◽  
Heidi Kiil Blomhoff ◽  
Sten Eirik Jacobsen ◽  
Stanislaw Krajewski ◽  
John C. Reed ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Peripheral Blood ◽  
Cell Apoptosis ◽  
Cell Types ◽  
Cd40 Ligand ◽  
Interleukin 13

Abstract Interleukin-13 (IL-13) is a novel T-cell–derived cytokine with IL-4–like effects on many cell types. In human B lymphocytes, IL-13 induces activation, stimulates proliferation in combination with anti-IgM or anti-CD40 antibodies, and directs Ig isotype switching towards IgE and IgG4 isotypes. We show here that IL-13 also regulates human B-cell apoptosis. IL-13 reduced spontaneous apoptosis of peripheral blood B cells in vitro, as shown by measurement of DNA fragmentation using the TUNEL and Nicoletti assays. The inhibition of cell death by IL-13 alone was significant but modest, but was potently enhanced in combination with CD40 ligand (CD40L), a survival stimulus for B cells by itself. Interestingly, IL-13 increased the expression of CD40 on peripheral blood B cells, providing a possible mechanism for the observed synergy. IL-13 alone was a less potent inhibitor of apoptosis than IL-4. Moreover, there was no additive effect of combining IL-4 and IL-13 at supraoptimal concentrations, which is consistent with the notion that the IL-4 and IL-13 binding sites share a common signaling subunit. The combination of IL-13 with CD40L augmented the expression of the Bcl-2 homologues Bcl-xL and Mcl-1, suggesting this as a possible intracellular mechanism of induced survival. By contrast, levels of Bcl-2, and two other Bcl-2 family members, Bax and Bak, remained unaltered. Given the importance of the CD40-CD40L interaction in B-cell responses, these results suggest a significant role of IL-13 in the regulation of B-cell apoptosis.

scholarly journals CELL INTERACTIONS IN THE IMMUNE RESPONSE IN VITRO

1972 ◽  
Vol 136 (4) ◽  
pp. 737-760 ◽  
Author(s):  
Marc Feldmann
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Interaction ◽  
T And B Lymphocytes ◽  
Activated T Cells ◽  
Cell Cooperation

The mechanism of interaction of T and B lymphocytes was investigated in an in vitro hapten carrier system using culture chambers with two compartments separated by a cell impermeable nucleopore membrane. Because specific cell interaction occurred efficiently across this membrane, contact of T and B lymphocytes was not essential for cooperation which must have been mediated by a subcellular component or "factor." By using different lymphoid cell populations in the lower culture chamber and activated thymus cells in the upper chamber (with antigen present in both), it was found that the antigen-specific mediator acted indirectly on B cells, through the agency of macrophages. Macrophages which had been cultured in the presence of activated T cells and antigen acquired the capacity to specifically induce antibody responses in B cell-containing lymphoid populations. Trypsinization of these macrophages inhibited their capacity to induce immune responses, indicating that the mediator of cell cooperation is membrane bound. By using antisera to both the haptenic and carrier determinants of the antigen as blocking reagents, it was demonstrated that the whole antigen molecule was present on the surface of macrophages which had been exposed to activated T cells and antigen. Because specifically activated T cells were essential a component of the antigen-specific mediator must be derived from these cells. By using anti-immunoglobulin sera as inhibitors of the binding of the mediator to macrophages, the T cell component was indeed found to contain both κ- and µ-chains and was thus presumably a T cell-derived immunoglobulin. It was proposed that cell cooperation is mediated by complexes of T cell IgM and antigen, bound to the surface of macrophage-like cells, forming a lattice of appropriately spaced antigenic determinants. B cells become immunized by interacting with this surface. With this mechanism of cell cooperation, the actual pattern of antigen-B cell receptor interactions in immunization would be the same with both thymus-dependent and independent antigens. An essential feature of the proposed mechanism of cell cooperation is that macrophage-B cell interaction must occur at an early stage of the antibody response, a concept which is supported by many lines of evidence. Furthermore this mechanism of cell interaction can be elaborated to explain certain phenomena such as the highly immunogenic macrophage-bound antigen, antigenic competition, the distinction between immunity and tolerance in B lymphocytes, and the possible mediation of tolerance by T lymphocytes.

scholarly journals The lipoprotein of the outer membrane of Escherichia coli: a B-lymphocyte mitogen.

1975 ◽  
Vol 142 (2) ◽  
pp. 473-482 ◽  
Author(s):  
F Melchers ◽  
V Braun ◽  
C Galanos
Keyword(s):  
Escherichia Coli ◽  
B Cells ◽  
B Cell ◽  
Outer Membrane ◽  
B Lymphocytes ◽  
Cell Activation ◽  
Thymidine Uptake ◽  
Mitogenic Stimulation ◽  
Amino Terminal ◽  
Stimulation Of

The lipoprotein of the outer membrane of Escherichia coli is a B-cell mitogen in mice. Polyclonal activation of B lymphocytes was measured by an increase in thymidine uptake, by the development of plaque-forming cells against densely coupled trinitrophenylated sheep red cells, and by selectively increased rates of synthesis and secretion of leucine-labeled IgM. Murein-free and muropeptides-containing lipoprotein are effective in B-cell activation, while free murein is inactive. Removal of ester-linked fatty acids from the amino-terminal end of the lipoprotein by alkaline hydrolysis abolishes the mitogenicity of the lipoprotein. B lymphocytes from high responder (C3H/Tif and BALB/c nu/nu) or from low responder (C3H/HeJ) mice to the mitogen lipopolysaccharide (LPS) both respond well to the lipoprotein. Anti-immunoglobulin antibodies inhibit the mitogenic stimulation of B cells by lipoprotein. A complex of structures including the Ig-receptor molecules, the LPS receptor, and the lipoprotein receptor appear involved in the regulation of mitogenic stimulation of B cells to proliferation and differentiation to IgM-secreting cells.

scholarly journals AB0024 IN VITRO CHARACTERIZATION OF CENERIMOD, A POTENT AND SELECTIVE SPHINGOSINE 1-PHOSPHATE RECEPTOR 1 (S1P1) MODULATOR IN PREVENTING MIGRATION OF NON-ACTIVATED AND ACTIVATED PRIMARY HUMAN B CELLS IN THE PRESENCE OR ABSENCE OF GLUCOCORTICOIDS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 1046.1-1046
Author(s):  
L. Schlicher ◽  
P. Kulig ◽  
M. Murphy ◽  
M. Keller
Keyword(s):  
B Cells ◽  
B Cell ◽  
B Lymphocytes ◽  
Cell Activation ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
B Cell Activation ◽  
Human B Cells ◽  
Circulating Lymphocytes

Background:Cenerimod is a potent, selective, and orally active sphingosine 1-phosphate receptor 1 (S1P1) modulator that is currently being evaluated in a Phase 2b study in patients with systemic lupus erythematosus (SLE) (NCT03742037). S1P1 receptor modulators sequester circulating lymphocytes within lymph nodes, thereby reducing pathogenic autoimmune cells (including B lymphocytes) in the blood stream and in inflamed tissues. Extensive clinical experience has become available for the nonselective S1P receptor modulator fingolimod in relapsing forms of multiple sclerosis, supporting this therapeutic concept for the treatment of autoimmune disorders.Objectives:Although the effect of S1P-receptor modulators in reducing peripheral B cells is well documented1,2, the role of the S1P1 receptor on this cell type is only incompletely understood. In this study, the mode of action of cenerimod on primary human B cells was investigated in a series of in vitro experiments, including S1P1 receptor cell surface expression and chemotaxis towards S1P. Moreover, S1P1 expression following B cell activation in vitro was studied. As glucocorticoids (GC) are frequently used in the treatment of patients with autoimmune disorders including SLE, the potential influence of GC on the mode of action of cenerimod was evaluated.Methods:Primary human B lymphocytes from healthy donors were isolated from whole blood. In one set of experiments, cells were treated with different concentrations of cenerimod to measure S1P1 receptor internalization by flow cytometry. In a second set of experiments, isolated B cells were activated using different stimuli or left untreated. Cells were then analysed for S1P1 and CD69 cell surface expression and tested in a novel real-time S1P-mediated migration assay. In addition, the effect of physiological concentrations of GCs (prednisolone and prednisone) on cenerimod activity in preventing S1P mediated migration was tested.Results:In vitro, cenerimod led to a dose-dependent internalization of the S1P1 receptor on primary human B lymphocytes. Cenerimod also blocked migration of nonactivated and activated B lymphocytes towards S1P in a concentration-dependent manner, which is in line with the retention of lymphocytes in the lymph node and the reduction of circulating lymphocytes observed in the clinical setting. Upon B cell activation, which was monitored by CD69 upregulation, a simultaneous downregulation of S1P1 expression was detected, leading to less efficient S1P-directed cell migration. Importantly, physiological concentrations of GC did not affect the inhibitory activity of cenerimod on B cell migration.Conclusion:These results show that cenerimod, by modulating S1P1, blocks B lymphocyte migration towards its natural chemoattractant S1P and demonstrate compatibility of cenerimod with GC. These results are consistent with results of comparable experiments done previously using primary human T lymphocytes.References:[1]Nakamura M et al., Mult Scler. 2014 Sep; 20(10):1371-80.[2]Strasser DS et al., RMD Open 2020;6:e001261.Disclosure of Interests:None declared

scholarly journals SELECTIVE TRIGGERING OF HUMAN T AND B LYMPHOCYTES IN VITRO BY POLYCLONAL MITOGENS

1974 ◽  
Vol 140 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Melvyn Greaves ◽  
George Janossy ◽  
Michael Doenhoff
Keyword(s):  
B Cells ◽  
B Lymphocytes ◽  
Human Lymphocytes ◽  
Culture Conditions ◽  
Pokeweed Mitogen ◽  
Cell Populations ◽  
T And B Cells ◽  
Activated T Cells ◽  
Lymphocyte Responses

Human lymphocytes from spleen and tonsils have been cultured with a variety of polyclonal mitogens. Cultures consisted of either unseparated T and B cells or alternatively purified T or B lymphocytes. The purity of the starting cell populations and the origin of activated lymphoblasts was analyzed with a panel of seven markers which discriminate between T and B cells. The selectivity of the lymphocyte responses was influenced by cell populations in a given culture, the mitogen used, and to a limited extent on culture conditions. Purified T lymphocytes from tonsil and spleen responded to phytohemagglutinin (PHA), pokeweed mitogen (PWM), and staphylococcal enterotoxin B (SEB). Purified B cells from spleen responded well to PWM, weakly to SEB and lipopolysaccharide, but not at all to PHA. Tonsil B cells responded weakly to PWM and SEB but not to PHA. Some B lymphocytes do respond to PHA in the presence of activated T cells. These results are discussed in relation to previously reported selective responses of human cells and parallel studies in animal species.

scholarly journals Interleukin 4 induces selective production of interleukin 6 from normal human B lymphocytes.

1989 ◽  
Vol 170 (4) ◽  
pp. 1463-1468 ◽  
Author(s):  
E B Smeland ◽  
H K Blomhoff ◽  
S Funderud ◽  
M R Shalaby ◽  
T Espevik
Keyword(s):  
B Cells ◽  
B Lymphocytes ◽  
Interleukin 6 ◽  
Specific Effect ◽  
Interleukin 4 ◽  
Tnf Alpha ◽  
Ifn Gamma ◽  
Normal Human ◽  
Tnf Secretion

In this paper we have shown that extensively purified human B lymphocytes respond to IL-4 treatment with a marked production of IL-6. Addition of anti-mu potentiated the effect of IL-4 on IL-6 production. Other cytokines tested like TNF-alpha and-beta, IFN-gamma, IL-1, IL-2, and IL-5 did not induce IL-6 secretion when given to resting B cells. Although B cells generally also produced TNF-alpha and TNF-beta upon stimulation, IL-4 did not induce TNF secretion and seemingly had a specific effect on IL-6 production.

E-cadherin is the major mediator of human melanocyte adhesion to keratinocytes in vitro

1994 ◽  
Vol 107 (4) ◽  
pp. 983-992 ◽  
Author(s):  
A. Tang ◽  
M.S. Eller ◽  
M. Hara ◽  
M. Yaar ◽  
S. Hirohashi ◽  
...  
Keyword(s):  
Cell Types ◽  
Melanoma Metastasis ◽  
Normal Keratinocytes ◽  
Human Melanocyte ◽  
Human Melanocytes ◽  
Dependent Cell ◽  
Normal Human ◽  
Pre Treatment ◽  
E Cadherin

E- and P-cadherin are calcium (Ca2+)-dependent cell adhesion molecules important in the morphogenesis and maintenance of skin structure. By use of flow cytometry and specific antibodies, we now show that cultured human melanocytes express E- and P-cadherin on their surfaces, and that these molecules have the same characteristics as reported for other cell types. Specifically, melanocyte cadherins are sensitive to trypsin digestion in the absence of Ca2+ and are protected from trypsin degradation by Ca2+, and are functional at 37 degrees C but not at 4 degrees C. We further show that melanocytes contain mRNA transcripts encoding both E- and P-cadherin. Adhesion of cultured melanocytes to keratinocyte monolayers is abolished by pre-treatment of the melanocytes with trypsin/EDTA, which degrades E- and P-cadherins, is greatly reduced by anti-E-cadherin antibodies and is slightly reduced by antibodies to P-cadherin, alpha 2, alpha 3 and beta 1 integrins. In contrast to normal melanocytes, eight of nine melanoma cell lines lacked E-cadherin (or expressed markedly reduced levels) and five were negative for P-cadherin. Melanoma cells also failed to adhere to keratinocyte monolayers. These results demonstrate that normal human melanocytes express functional E- and P-cadherin and that E-cadherin is primarily responsible for adhesion of human melanocytes to keratinocytes in vitro. In addition, transformed melanocytes express markedly reduced levels of E- and P-cadherin, and exhibit decreased affinity for normal keratinocytes in vitro, suggesting that loss of cadherins may play a role in melanoma metastasis.

scholarly journals Autologous stimulation of human lymphocyte subpopulation.

1975 ◽  
Vol 142 (5) ◽  
pp. 1327-1333 ◽  
Author(s):  
G Opelz ◽  
M Kiuchi ◽  
M Takasugi ◽  
P I Terasaki
Keyword(s):  
T Cells ◽  
B Cells ◽  
B Lymphocytes ◽  
Human Lymphocyte ◽  
Lymphocyte Subpopulation ◽  
High Background ◽  
Background Stimulation ◽  
Most Probable Explanation ◽  
Stimulation Of

The background stimulation universally seen when lymphocytes are cultured in vitro has been shown to be markedly lowered by reducing the proportion of B lymphocytes. B-rich fractions of lymphocytes had extremely high background stimulation. It is concluded that stimulation of T cells, probably by autologous B cells, provides the most probable explanation for the findings described.

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