The biology of natural killer cells, J. O'Shea and J.R. Ortaldo natural killer cells in haematopoiesis, G. Trinchieri natural killer cells in bacterial injection, P. Garcia-Penarrubia natural killer cells in viral infection, R.M. Welsh and M. Vargas-Cortes natural killer cells in transplantation, P.C. Hogan natural killer cells in tumour biology, C.E. Lewis and J.O'D. McGee natural killer cells / large granualar lymphocytes in pregnancy, P.M. Starkey.