TY  - JOUR
A1  - Vogt, Birgit
A1  - Warncke, Marit
A1  - Micheel, Burkhard
A1  - Sheriff, Ahmed
T1  - Lentiviral gene transfer of CTLA4 generates B cells with reduced costimulatory properties : brief definite report
N2  - Peripheral T-cell (TC) tolerance can be induced by tolerogenic antigen-presenting cell (APC). A prerequisite is the reduction or blockade of B7 of APC. Besides dendritic cell, B cells can be used as APC. Here, we show the generation B cells with reduced B7 expression by lentiviral transduction of endoplasmic reticulum (ER)-directed CTLA4. Vectors coding for the human CTL4-Ig were used for the human B-cell line Raji. Transduction efficiency was over 90% (MOI = 3). For the murine B-cell line A20 and for primary mouse B cells, murine CTLA4 was used. We show that B cells with reduced B7 expression reduce the antigen (Ag) specific TC proliferation in vitro. B cells expressing an ER-directed CTLA4 may reduce Ag-specific immune responses.
Y1  - 2009
UR  - http://informahealthcare.com/loi/aut
U6  - https://doi.org/10.1080/08916930902832470
SN  - 0891-6934
ER  - 
TY  - JOUR
A1  - Sheriff, Ahmed
A1  - Vogt, B.
A1  - Baumgart, Martin
A1  - Montag, C.
A1  - Hollenbach, B.
A1  - Schenk, Jörg A.
A1  - Ulrich, J.
A1  - Ellias, F.
A1  - Micheel, Burkhard
T1  - Intracellular capture of B7 in antigen-presenting cells reduces costimulatory activity
N2  - CTLA-4 gene constructs were designed to express CTLA-4 exclusively in the endoplasmic reticulum (ER). Four different CTLA-4 gene constructs were transfected into HEK 293 (human embryonic kidney) and A20 (Balb/c mouse B lymphoma) cells. All constructs contained an ER retention signal and coded for CTLA-4 expression in the ER. One of the constructs, which contained the membrane part of CTLA-4, coded for an expression both on the cell surface and in the ER. Three of the expressed CTLA-4 types (including the ER-membrane-expressed form) caused a reduced surface expression of B7 in the A20 cells. Only constructs which allow dimerization of CTLA-4 showed this effect. It is assumed that intracellular CTLA-4 bound B7 and inhibited therefore the transport of B7 to the surface. The binding obviously caused also an enhanced degradation of the complexes because both proteins showed a low concentration in the transfected cell lines. CTLA-4-transfected and B7-reduced A20 cells showed a diminished costimulating activity upon T cells. This was demonstrated by a reduced proliferation of T cells from ovalbumin-immunized Balb/c mice, incubated with ovalbumin peptide-primed CTLA-4-transfected A20 cells.
Y1  - 2003
UR  - http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBK-47T23XK- 8&_coverDate=02%2F21%2F2003&_alid=268969757&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6713&_sort=d&view=c&_acct=C000053886&_v e
ER  - 
TY  - JOUR
A1  - Warncke, Max
A1  - Vogt, Birgit
A1  - Ulrich, Jacqueline
A1  - von Laer, Meike Dorothee
A1  - Beyer, Winfried
A1  - Klump, Hannes
A1  - Micheel, Burkhard
A1  - Sheriff, Ahmed
T1  - Efficient in vitro transduction of naive murine B cells with lentiviral vectors
N2  - The aim of this study was to determine the impact of lentiviral transduction on primary murine B cells. Studying B cell activities in vivo or using them for tolerance induction requires that the cells remain unaltered in their biological behavior except for expression of the transgene. As we show here, murine B cells can efficiently be transduced by lentiviral, VSV-G-pseudotyped vectors without the necessity of prior activation. Culture with LPS gave enhanced transduction efficiencies but led to the upregulation of CD86 and proliferation of the cells. Transduction of naive B cells by lentiviral vectors was dependent on multiplicity of infection and did not lead to a concomitant activation. Furthermore, the transduced cells could be used for studies in the NOD mouse system without altering the onset of diabetes. We conclude that lentiviral gene transfer into naive B cells is a powerful tool for manipulation of B cells for therapeutic applications.
Y1  - 2004
UR  - http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WBK-4C707VR- 7&_coverDate=06%2F04%2F2004&_alid=269000954&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=6713&_sort=d&view=c&_acct=C000053886&_v e
ER  -