1.3E2, a variant of the B lymphoma 70Z/3, defective in activation of NF-kappa B and OTF-2.

The mouse B-cell cell lymphoma 70Z/3 is a convenient model system in which to study the regulation of immunoglobulin synthesis. Three transcriptional activators of kappa (kappa) light chain synthesis have been identified for these cells: bacterial lipopolysaccharide (LPS), interferon-gamma (IFN), and interleukin-1 (IL-1). The response of the kappa gene in 70Z/3 cells to LPS is mediated by increases in two transcription factors: NF-kappa B and OTF-2. In contrast, IFN has no effect on either of these factors in 70Z/3 cells. We have isolated by immunoselection an LPS- IFN+ variant of 70Z/3 called 1.3E2. We show here that LPS treatment of these cells causes no increase in nuclear localization of either NF-kappa B or OTF-2. Although they have normal levels of cytoplasmic NF-kappa B, it cannot be activated by LPS or by phorbol 12-myristate 13-acetate (PMA) treatment of the cells. These experiments expand the genetic dissection of the molecular pathways of activation of kappa transcription in 70Z/3 cells.