This observation is similar to those found during acute viral infection; indeed, during, for example, acute human immunodeficiency virus type 1 infection, the NK cell expansion may be first associated with a non specific expansion of activating KIR-expressing NK cells, which however is followed by the occurrence of a protective KIR3DL1+ expressing NK cells, but only in the presence of their putative, HLA-Bw4-I80 ligand [65]. Here, KIR3DL1 is linked to viral infectious disease.