A simple subtraction method for the isolation of cell-specific genes using magnetic monodisperse polymer particles.

In this study we present a simple subtraction method for the isolation of cell-type-specific genes using magnetic beads. Biotinylated first-strand cDNA is generated from one cell type and immobilized onto magnetic streptavidin beads. Poly A+ RNA, isolated from a different cell type by use of oligo-dT beads, is then hybridized to the immobilized cDNA. Beads with hybridized mRNA are subsequently removed from the solution by attraction to a magnet. The cell-specific mRNA, left in solution, is finally converted to a radiolabeled cDNA probe in order to screen cDNA libraries. In this study, we present an example of a successful subtraction strategy involving three cell types: the pre-B-cell line Reh; 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated Burkitt's lymphoma line Daudi; and TPA-stimulated T lymphocytes. This strategy was chosen due to our interest in gene products known to be expressed in TPA-stimulated B and T lymphocytes, but not in Reh cells. Several previously unknown genes were identified.