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Regulation of immunoglobulin gene expression in normal lymphocytes II. Mechanisms of down‐regulation of immunoglobulin secretion after engagement of the B cell antigen receptor
Author(s) -
Berberich Ingolf,
Schimpl Anneliese
Publication year - 1992
Publication title -
european journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 201
eISSN - 1521-4141
pISSN - 0014-2980
DOI - 10.1002/eji.1830220235
Subject(s) - ionomycin , biology , secretion , microbiology and biotechnology , protein kinase c , receptor , antibody , phorbol , messenger rna , antigen , stimulation , b cell , gene expression , signal transduction , gene , endocrinology , immunology , biochemistry
Abstract When B cells are stimulated with lipopolysaccharide (LPS) they start to proliferate and mature into immunoglobulin (Ig)‐secreting cells. Co‐stimulation with F(ab') 2 fragments of antibodies directed against the B cell antigen receptor leads to an inhibition of Ig secretion but not of proliferation. This effect can be mimicked by phorbol esters alone or by a combination of phorbol esters and the Ca 2+ ionophore ionomycin, which activate protein kinase C. Here we report that co‐stimulation with phorbol esters and ionomycin differentially affects a group of genes normally up‐regulated during the course of LPS‐dependent B cell activation. Thus, the mRNA coding for the membrane‐bound form of IgM and the interleukin 2 receptor (55‐kDa protein) continue to be expressed at the levels typical of LPS‐stimulated cells, while the mRNA coding for the secreted form of IgM (μs) and for the J chain are reduced. The loss of μ S mRNA is attributable to an altered processing behavior with respect to the μ precursor and/or a decreased stability of the mRNA itself.