Dendritic cells and NK cells

[HHarada]

Somebody, tell me about meaning of interaction of DC and NK cells in vivo.

Recently, it has been reported that NK cells recognize and kill autologous
dendritic cells in vitro. Authors in a paper describe
that the interaction induce increase　of killing activity and IFN-g　
production. However, my question is why NK cells kill such a useful cells in
vitro.
Does this phenomenon occur in vivo actually ?

Please, somebody help me.

Hideki Harada