Transgenic Expression of Insulin Receptor Substrate 2 in Murine B Cells Alters the Cell Density-Dependence of IgE Production In Vitro and Enhances IgE Production In Vivo

DOI PubMed Open Access

Search this article

Description

<jats:title>Abstract</jats:title> <jats:p>Previous studies have shown that insulin receptor substrate (IRS)1 and IRS2 mediate proliferative and antiapoptotic signaling through the IL-4R in 32D cells; however their role in regulating normal B cell responses is not clear. To investigate the role of IRS2 in normal B cell function, we developed IRS2 transgenic (Tg) mice on the C57BL/6 background. Western blot analysis revealed a 2-fold elevation in IRS2 protein levels in Tg+ mice compared with littermate controls and a 3-fold increase in basal tyrosine phosphorylated IRS2 in the absence of IL-4 stimulation. IL-4-induced tyrosine phosphorylation of IRS2 was elevated in Tg+ B cells, whereas IL-4-induced phosphorylation of STAT6 was similar between Tg+ and Tg− B cells. Tg expression of IRS2 had little effect on IL-4-mediated proliferation and no effect on protection from apoptosis. However, production of IgE and IgG1 by Tg+ B cells using standard in vitro conditions was diminished 50–60%. Because Ig production in vitro is known to be highly cell concentration-dependent, we performed experiments at different cell concentrations. Interestingly, at very low B cell concentrations (1000–5000 B cells/well), IgE and IgG1 production by Tg+ B cells was greater than that of controls, whereas at higher cell concentrations (10,000–20,000 cells/well) Ig production by Tg+ B cells was less than controls. Furthermore, in vivo immunization with OVA-alum or goat anti-IgD resulted in elevated serum IgE levels in the Tg+ mice. These results indicate that overexpression of IRS2 alters the B cell intrinsic density-dependence of IgE and IgG1 production in vitro and enhances IgE responses in vivo.</jats:p>

Journal

Keywords

Details 詳細情報について

Report a problem

Back to top