Efficient migration of dendritic cells toward lymph node chemokines and induction of T(H)1 responses require maturation stimulus and apoptotic cell interaction.

Dendritic cells (DCs) have the unique ability to initiate primary immune responses, and they can be conditioned for vaccinal purposes to present antigens after the engulfment of apoptotic cells. To recruit the rare antigen-specific naive T cells, DCs require a maturation step and subsequent transport toward lymph node (LN). To date, prostaglandin E2 (PGE2) is the best-characterized compound inducing this LN-directed migration in vitro, but PGE2 may skew the immune responses in a T(H)2 direction. We demonstrate here that on incubation with apoptotic tumor cells and tumor necrosis factor-alpha (TNF-alpha) or lipopolysaccharide (LPS), human monocyte-derived DCs become fully mature and acquire high migratory capacities toward LN-directing chemokines. The migration of TNF-alpha-treated DCs occurs only after cotreatment with apoptotic cells but not with necrotic cells. DC migration requires CD36 expression and incubation with apoptotic cells in the presence of heat-labile serum components. Moreover, on treatment with apoptotic cells and LPS, the migrating DCs are able to recruit naive T cells to generate T(H)1 immune responses. Our results show that the cotreatment of DCs with apoptotic tumor cells and inflammatory signals is promising for the design of an antitumoral DC-based vaccine.