Abstract: Compositions of matter and methods for expressing a polypeptide are provided. In one aspect, a gene construct is provided that comprises an enhancer comprising particular elements or combinations of elements from the immunoglobulin &kgr; locus, the immunoglobulin heavy chain &mgr; locus, and the immunoglobulin &lgr; locus, and a promoter and polyadenylation site linked to a nucleotide sequence encoding a polypeptide from a select group. Cells comprising the gene construct, processes for producing such cells, and processes for producing the polypeptide encoded by the gene construct from such cells are also provided.

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 relates to a DNA construct and to a method of detecting tumor promoters by employing this DNA construct.It is an object of the invention to make available an easily implemented quantitative detection method for tumor promoters.This is accomplished by a DNA construct including at least one reporter gene and a control region for the activation of a particularly strongly induced gene of the Epstein-Barr virus (EBV), and by the action of the substance to be examined on EBV-containing cells that contain the DNA construct, whereupon the resulting quantity of reporter gene product is quantitatively determined.