Class II-targeted antigen is superior to CD40-targeted antigen at stimulating humoral responses in vivo

We examined the efficacy of using monoclonal antibodies to target antigen ( avidin) to different surface molecules expressed on antigen presenting cell s (APC). In particular, we targeted CD40 to test whether the "adjuvant" pro perties of CD40 signaling combined with targeted antigen would result in en hanced serologic responses. We targeted avidin to class II as a positive co ntrol and to CD11c as a negative control. These surface proteins represent an ensemble of surface molecules that signal upon ligation and that are exp ressed on professional APC, in particular dendritic cells (DC). We observed that targeting class II molecules on APC was superior to targeting CD40, o r CD11c. However, CD40 and CB11c could function as targets for antigen boun d monoclonal antibodies under certain conditions. Interestingly, inclusion of anti-CD40 mAb with the targeting anti-class II-targeted antigens negativ ely affects humoral response, suggesting that CD40 signaling under certain conditions may suppress processing and/or presentation of targeted antigen. (C) 2001 Published by Elsevier Science B.V.