Microbe Complement Bound activation C3d CR2 Recognition 八cD19 by b cells ga CD81 Signals from Ig and cR2 complex B cell activation C Elsevier. Abbas Lichtman: Basic Immunology, Updated 2ebade www ddenteensglteeomDownloaded from: StudentConsult (on 1 June 2006 03:50 PM) © 2005 Elsevier