EBV transformation of B cells

Steps must be taken to remove or counter cytotoxic T cells which may kill the virally-infected B cells. About 90% of adults have been infected with EBV and will have developed T cell immunity. This T cell abrogation can be achieved by 

HUMAN MONOCLONAL ANTIBODIES TO BLOOD GROUP ANTIGENS 

T cell depletion or, more simply, by addition of PHA (ph5 ohaemagglutinin, which activates T helper cells) or cyclosporin A (which depletes cytotoxic T cells). Greater success was obtained with PHA than with cyclosporin A in the production of monoclonal antibodies (5). 

Epstein-Barr vims is a human hei pes virus and infects human B cells by binding 10 the C3d complement receptor (CR2, CD21), This receptor is not expressed on other leucocytes. B cells are initially activated by the vims, a minority then become transformed, and subsequently a fraction of these develop immortality, when the EBV genome has integrated into the host cell DNA. Thus EBV-transformed B cell lines (B-lymphoblastoid cell lines, B-LCL) will develop from less than 1% of the original B cells. Greater efficiency of immortalization can be achieved with the use of EBV of high litre. 

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The Epstein-Barr virus (EBV) is a herpesvirus that is associated with the formation of lymphomas and nasopharyngeal carcinomas. It infects most humans but infections in childhood are generally asymptomatic. In young adults it can cause glandular fever, a chronic condition in which there is proliferation of white blood cells. After infection the virus becomes latent in B lymphocytes for the lifetime of the individual. In vitro the infection of B lymphocytes by EBV results in their transformation and proliferation. Normally in vivo, this EBV-induced proliferation of B cells is kept under control by the action of T-killer lymphocytes. In some African children infection with EBV induces Burkitt s lymphoma, a particularly malignant tumour of the jaw. The characteristic occurrence of this condition in hot humid regions of Africa where mosquitoes flourish has led to the hypothesis that infection with EBV has to be followed by malaria before the lymphomas will develop. Suppression of... 

Antibodies are expressed by hybridoma cells formed by cell fusion of sensitized animal or human B lymphocytes with myeloma cells, or they are generated by EBV (Epstein-Barr virus) transformation of sensitized B lymphocytes. Other heterologous expression systems such as bacteria, yeast, insect cells, and mammalian cells have also been used for expression of antibodies and their fragments. However, because of renaturation problems, glycosylation, and expression levels, mammalian cells are mostly used for the expression of monoclonal antibodies. More recently, technologies have been extensively developed for the expression of antibodies in transgenic animals and transgenic plants. 

Gauchat, J.F., Gascan, H., de Waal Malefyt, R, and de Vries, J.E. (1992b). Regulation of germ-line epsilon transcription and induction of epsilon switching in cloned EBV-transformed and mal ant human B cell lines by cytokines and CD4 T cells. J. Immunol. 148, 2291-2299. 

Epstein-Barr virus (EBV)-transformed homozygous human B-cell lines were used as a source for isolating HLA class II molecules. In the case of isolation of HLA-DR1, WT-100 cell pellets were lyzed by NP-40, and DR1 was isolated from homogenates by affinity chromatography with the monoclonal antibody L243 essentially as described [64,65].The purity of the preparation was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), HPSEC and Western blotting. 

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