Enhancer-dependent expression of human kappa immunoglobulin genes introduced into mouse pre-B lymphocytes by electroporation.

We have developed a general method for introducing cloned genes into mammalian cells that affords substantial benefits over current technology. It is simple, rapid, and applicable to many (perhaps all) cell types, including those that are refractory to traditional transfection procedures. The method involves exposure of a suspension of cells and cloned DNA to a high-voltage electric discharge. In a model application of this transfection procedure, we have studied the expression of cloned human and mouse Ig kappa genes stably introduced into mouse pre-B cells and fibroblasts. We find that there is a B-cell-specific enhancer-activator region in the J-C intron of the human kappa gene that is necessary for efficient transcription of the cloned gene in mouse pre-B lymphocytes. This suggests that both the DNA element and the proteins required for its regulatory activity have been highly conserved in evolution and that these elements operate at the pre-B-cell stage of immunocyte development, a stage that precedes productive kappa gene rearrangement.