Targeting of antigens to antigen presenting cells (APC) results in enhanced antigen presentation and T cell activation. In this paper, we describe a novel targeting reagent denoted "Troy-bodies", namely recombinant antibodies with APC-specific V regions and C regions with integrated T cell epitopes. We have made such antibodies with V regions specific for either IgD or MHC class II, and four different T cell epitopes have been tested. All four epitopes could be introduced into loops of C domains without disrupting Ig folding, and they could be released and presented by APC. Furthermore, whether IgD- or MHC-specific, the molecules enhanced T cell stimulation compared to non-specific control antibodies in vitro as well as in vivo. Using this technology, specific reagents can be designed that target selected antigenic peptides to an APC of choice. Troy-bodies may therefore be useful for manipulation of immune responses, and in particular for vaccination purposes.