Dendritic cells directly trigger NK cell functions: Cross-talk relevant ininnate anti-tumor immune responses in vivo

Cytotoxic T lymphocytes and natural killer cells are essential effecters of anti-tumor immune responses in vivo. Dendritic cells (DC) 'prime' tumor an tigen-specific cytotoxic T lymphocytes; thus, we investigated whether DC mi ght also trigger the innate, NK cell-mediated anti-tumor immunity. In mice with MHC class I-negative tumors, adoptively transferred- or Flt3 ligand-ex panded DC promoted NK cell-dependent anti-tumor effects. In vitro studies d emonstrated a cell-to-cell contact between DC and resting NK cells that res ulted in a substantial increase in both NK cell cytolytic activity and IFN- gamma production. Thus, DC are involved in the interaction between innate a nd adaptive immune responses.