Transfection of an immunoglobulin kappa gene into mature human B lymphocytes

Activation of immunoglobulin control elements in transgenic mice

To assess the role interleukins and mitogens play in regulating immunoglobulin (Ig) gene expression via the Ig enhancer and promoter, transgenic mice carrying two different Ig gene regulatory regions were generated. One, EmukCAT, contains the Ig heavy chain enhancer (Emu) and the kappa light chain promoter driving the chloramphenicol acetyltransferase (CAT) gene. In the other, delta EmukCAT, CAT is under the control of the kappa promoter alone. Emu and kappa relative activity were assessed by CAT assay. In EmukCAT mice, low CAT expression was consistently found in spleen, bone marrow, mesenteric lymph node, and thymus but not in brain, lung, or kidney. In delta EmukCAT mice, CAT expression was detectable just above background in lymphoid tissues, suggesting a basic level of tissue specificity in the absence of the enhancer. Whole spleen cell cultures prepared from the mice were treated with lymphokines and mitogens. Lipopolysaccharide (LPS), concanavilin A (Con A), interleukin 6 (IL-6), and interferon-gamma (IFN-gamma) increased CAT expression to varying extents in cells derived from EmukCAT mice but not in spleen cells prepared from delta EmukCAT mice. Thus, the presence of Emu, in addition to the kappa promoter, is essential for the stimulation of CAT expression mediated by these factors. B cells from EmukCAT mice were separated by density into populations of small and large cells. In untreated small B cells, no CAT expression was detected and only addition of LPS resulted in an increase in CAT expression. In large B cells, CAT was expressed at a low level without addition of exogenous factors. Incubation with LPS, IL-6, Con A and IFN-gamma caused CAT expression to increase several-fold. This transgenic system provides a means to identify exogenous factors that activate Ig enhancers and promoters.

Restoration of high immunoglobulin gene expression in chronic lymphoid leukemia: a possible application for gene therapy

In this study, using interleukin-2 and gamma interferon, we first induced the differentiation into plasma cells of primary chronic lymphoid leukemic B cells from patients whose T cells failed to produce interleukin-2. We next demonstrated that these malignant primary B lymphocytes (i.e., lymphocytes which have not been subjected to any procedure aiming at their immortalization or their transformation into cell lines) functionally expressed transfected genes under the control of exogeneous Ig promoters and enhancers during their terminal differentiation into plasma cells. We discussed the possibility of applying this approach to gene therapy to correct this type of lymphocytic leukemia in man.