We have recently reported that NK cells can specifically recognise cells in mitosis, perhaps using cell division as an indicator for potential danger [Blood. 2007; 109:670-3]. We are currently probing the mechanisms and functions for this. We have also recently reported a reciprocal regulation between macrophages and NK cells [Blood. 2007; 109:3776-85]. This interaction may be important in a variety of circumstances including immune responses to malaria [J Immunol. 2005; 175:7466-73, J Immunol. 2003; 171:5396-405].