Bacterial lipopolysaccharide induced B cell activation is mediated via a phosphatidylinositol 3-kinase dependent signaling pathway

sBacterial lipopolysaccharide (LPS) is a potent stimulant of B cells and ma crophages. LPS induces B cell proliferation and differentiation into antibo dy secreting cells. In addition, LPS also stimulates IL-6 secretion in matu re B cells and in immature B cell lines such as WEHI-231. Although sufficie nt literature is available on LPS induced signaling events in monocytes and macrophages, the mechanisms involved in LPS induced B cell activation are not well understood. In this report, it is shown that both LPS mediated B c ell proliferation and IL-6 secretion are dependent on phosphatidylinositol 3-kinase (PI 3-kinase) signaling pathways. The B cell specific co-receptor, CD19 is not tyrosine phosphorylated in LPS stimulated B cells. Thus, in co ntrast to B cell antigen receptor (BCR) signaling, the activation of PI 3-k inase appears not to be related to the recruitment of PI 3-kinase to tyrosi ne phosphorylated CD19. This is the first demonstration of the importance o f PI 3-kinase signaling pathway in LPS mediated B lymphocyte activation. (C ) 1999 Elsevier Science B.V. All rights reserved.