Journal Article

Induction of B cell apoptosis by co-cross-linking CD23 and sIg involves aberrant regulation of c-myc and is inhibited by bcl-2.

K A Campbell, E J Studer, M A Kilmon, A Lees, F Finkelman and D H Conrad

in International Immunology

Published on behalf of Japanese Society for Immunology

Volume 9, issue 8, pages 1131-1140
Published in print August 1997 | ISSN: 0953-8178
Published online August 1997 | e-ISSN: 1460-2377 | DOI: http://dx.doi.org/10.1093/intimm/9.8.1131
Induction of B cell apoptosis by co-cross-linking CD23 and sIg involves aberrant regulation of c-myc and is inhibited by bcl-2.

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A novel system to study the effects of co-cross-linking CD23/FceRII and sIg on murine B lymphocytes utilizes a highly multivalent form of anti-Ig prepared by covalently linking anti-Ig antibodies to a DNP-dextran backbone. CD23-sIg co-cross-linking is accomplished by the addition of DNP-specific monoclonal IgE. Previous studies demonstrated that co-cross-linking CD23 and sIg significantly inhibited mouse B cell proliferation, especially at high doses of the multivalent anti-Ig. Interestingly, examination of early activation signals reveals no difference in B cells subjected to co-cross-linking conditions as compared to B cells activated with anti-Ig alone. Total cellular protein tyrosine phosphorylation levels are unchanged by co-cross-linking. Analysis of B cell mRNA reveals that co-cross-linking the receptors does not alter the expression levels of ornithine decarboxylase 8 h after stimulation as compared to the controls. In contrast, levels of the proto-oncogene c-myc were significantly elevated 1 h after inducing B cell activation under co-cross-linking conditions. However, it remains unclear whether this aberrant c-myc regulation plays any role in inducing apoptosis. In addition, on day 3 after stimulation, the co-cross-linking of CD23 and sIg resulted in the formation of apoptotic B cells, determined by both photomicroscopy of the B cell cultures and FACS analysis of B cell nuclei. B cells obtained from bcl-2 transgenic mice proliferated as well as controls, and failed to undergo apoptosis when CD23 and sIg were co-cross-linked on their surface. These studies indicate that co-cross-linking of CD23 with B cell sIg inhibits B cell proliferation by a mechanism that is distinct from that seen by co-cross-linking of the Fc gamma RII and sIg. In addition, these results suggest a means by which antigen-specific IgE can down-regulate additional B cell activation and IgE synthesis.

Journal Article.  0 words. 

Subjects: Immunology ; Biological Sciences

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