CD86 Stimulation on a B Cell Activates the Phosphatidylinositol 3-Kinase/Akt and Phospholipase Cγ2/Protein Kinase Cαβ Signaling Pathways

Abstract

Stimulation of CD86 on a CD40L/IL-4-activated murine B cell increases the rate of mature IgG1 transcription by increasing the level of NF-κB activation, as well as Oct-2 expression and binding to the 3′-IgH enhancer. The signal transduction pathway activated by CD86 proximal to NF-κB activation is unknown. In this study, we show that CD86 stimulation on an activated B cell increases the activity of PI3K and the phosphorylation of phosphoinositide-dependent kinase 1, Akt, and IκB kinase αβ. In addition, CD86 stimulation induces an increase in the phosphorylation of phospholipase Cγ2 and protein kinase C αβ. CD86-mediated activation of these two signaling pathways leads to increased Oct-2 expression, increased gene activity mediated by NF-κB and 3′-IgH enhancer increased activity. These results identify a previously unknown signaling pathway induced by CD86 to regulate the level of B cell gene expression and activity.