Engineering cross-presentation in vivo

Apoptotic bodies deliver antigens (Ags) to the cross-presentation pathways of dendritic cells (DCs), where their presentation has been associated with both the maintenance of tolerance as well as the induction of protective immunity. The manner in which apoptotic bodies are generated, their abundance in relation to local DCs, and the milieu in which they are generated appear to be the major factors determining whether apoptotic bodies will induce CD8+ T cell activation or anergy. These observations have been extended to the field of vaccination, where the engineered apoptosis of Ag-bearing/loaded cells in vivo has been used to prime strong CD8+ T cell immunity. This review will examine Ag capture and cross-presentation by DCs, with particular emphasis on the manipulation of apoptotic bodies in vivo for the purpose of vaccination.