Fig. 3

Differences between CD56^bright and CD56^dim NK cells during aging. During aging, CD56^bright NK cells are decreased in circulation while their counterpart CD56^dim NK cells increase their numbers in blood. Both in circulating CD56^bright and CD56^dim NK cells, the expression of the receptor CD94 and natural cytotoxicity receptors (NCRs) NKp30 and NKp46 is decreased in elderly subjects, whereas the expression of killer-cell immunoglobulin-like receptors (KIRs) seems to be upregulated only in CD56^bright NK cells. The expression of DNAM-1 seems to be decreased mostly in CD56^dim NK cells with age. These phenotypic changes might explain the decreased cytotoxicity observed during aging [67]