Migration of dendritic cell based cancer vaccines: in vivo veritas?

Ex vivo generated cancer vaccines based on dendritic cells (DCs) are currently applied in the clinic. The migration of DCs from the tissues to the lymph nodes is tightly controlled and involves many different mediators and their receptors. A recent study demonstrated that the rate of migration of antigen-bearing DCs in situ from the skin to the lymph node is 100-fold higher than previously estimated. The migration of ex vivo generated DCs is rather inefficient but can be improved by pre-conditioning of the vaccine injection site with inflammatory cytokines. An alternative approach that is currently being explored is to target tumor antigens directly to DCs in situ, thereby exploiting the intricate migratory capacity of DCs in vivo. Recent advances have been made in understanding DC migration in the context of DC-based vaccines.