Abstract: T cells having a desired antigen specificity are stimulated by (a) introducing immortalizing genes into antigen-presenting cells in a manner permitting regulation of the expression and/or function of at least one of these genes to achieve conditionally immortalized antigen-presenting cells; (b) introducing a gene encoding the desired antigen into the immortalized cells in a manner permitting the antigen to be expressed after the expression and/or abolishment of the function of at least one of the immortalizing genes stops; (c) expanding the immortalized antigen-presenting cells by expression and/or functional activation of the immortalizing genes; (d) completing the proliferation of the immortalized antigen-presenting cells by stopping the expression and/or abolishing the function of at least one of the controllable immortalizing genes; (e) continuing the expression of the antigen; (f) adding leucocytic cells including T cells and cultivating the cell mixture to stimulate the T cells directed against the desi

Abstract: The invention is directed to a method for the preparation of a conditionally immortalized immortalization-helper cell (fuseme), the fusemes generated by said method, hybridoma cells prepared using said fusemes as well as a method for immortalization of mammalian cells using said fuseme cells. Further, the invention relates to the generation of T cells directed agaist tumor cells using a fuseme cell.

Abstract: The present invention provides a process for the preparation of human monoclonal antibodies from human B cells. According to this process, human antibody-producing B cells are immortalized by infection with an Epstein-Barr virus, or derivative thereof, that expresses Epstein-Barr virus nuclear antigen 2 (EBNA2). EBNA2 function, which is required for immortalization, is subsequently shut off, which results in an increase in antibody production. The invention provides a variety of systems that allow expression of EBNA2 function to achieve immortalization, followed by reduction of EBNA2 expression or function to facilitate antibody production.