Proinflammatory status influences NK cells subsets in the elderly.

Aging is associated to dysfunctional changes in the immune system, a process termed immunosenescence. Elderly individuals usually present chronic low level inflammation, likely as the consequence of continued exposure to antigens combined with poor immune function, increases in production of pro-inflammatory cytokines by effector memory and senescent T cells and macrophages. This condition not only results from, but also drives immunosenescence. Aging affects all cell components of the immune system, including NK cells and its different subsets (CD56dimCD16+, CD56brightCD16+/- and CD56-CD16+). In particular, the percentage of total NK cells is increased in healthy aging and centenarians, whereas there is a decrease in the CD56bright NK cell subset and an expansion of CD56-CD16+ NK cells. However, the causes of these alterations on NK cells in old donors are not fully understood. In this work we analyse NK cell subsets in the elderly in relation with markers of inflammation and health status. The results show that there is a positive correlation between the number of total NK cells and the body mass index (BMI), while the number of CD56bright NK cells negatively correlates with the levels of C-reactive protein (CRP), supporting that chronic inflammation is involved in the decrease of this NK cell subset.