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  • Title: 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: Berberich I, Schimpl A.
    Journal: Eur J Immunol; 1992 Feb; 22(2):525-9. PubMed ID: 1537386.
    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 Ca2+ 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 (mu S) and for the J chain are reduced. The loss of mu S mRNA is attributable to an altered processing behavior with respect to the mu precursor and/or a decreased stability of the mRNA itself.
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