B cell presents Helper T ce‖l B cells are B cel antigen to is activated activated by helper T cell expresses CD40L,CD40 engagement, //proliferation and secretes cytokines cytokines differentiation CD40 CD40 CD40 ligand ligand x B ce cell CD28 B7 Cytokine receptor Cytokines Cytokines @ElsevierAbbas&LichtmanBasicImmunologyUpdated2e-www.studentconsult.com Mechanisms of th cell-mediated activation of b cells Down/oaded from Student ConsultDownloaded from: StudentConsult (on 1 June 2006 03:50 PM) © 2005 Elsevier Mechanisms of Th cell-mediated activation of B cells