Inhibitory receptors for MHC class I molecules were initially characterised
on NK cells. Human and mouse NK cell receptors (NKRs) are also expressed o
n T cells, predominantly on a subset of memory-phenotype CD8(+) T cells. Th
is review focuses on the precise determination of interactions between NKRs
and MHC class I, as well as on the unexpected in vivo function of NKRs on
T cells.