NK Receptors Corresponding Ligand/Cell Receptors
Inhibitory signals KIR2DL1 HLA-C group 2
KIR2DL2/3 HLA-C  group 1
 KIR3DL1 HLA-Bw4
KIR3DL2 HLA-A3 and HLA –A11
LIR-1 HLA class I molecules
NKG2A HLA-E
Activating signals KIR2DS1 HLA-C
NKG2D ULBP-1-ULBP4, MICA and MICB
NKp46 Viral heamagglutinin
CD16 igG
BY55 HLA-c
Table 2: NK cells harbour two sets of receptors; inhibitory and activating. Depending on the interaction of the ligand with the corresponding receptor, NK will signal the activating or inhibitory downstream cascade. In addition to the ligand/receptor interaction, debris from apoptotic and tumour cells, cytokines and costimulatory ligands as well dendritic cells can potentially skew the relevant signal, the interaction and hence the immune outcome.