NK cells in human ageing

Abstract

NK cells are cytotoxic lymphocytes that are involved in the early defense against virus infected and tumor cells. NK cells exhibit the capacity to distinguish normal and damaged cells as well as self- and foreign cells. Besides their cytotoxic capacity NK cells also regulate the immune response by producing cytokines and chemokines that directly participate in the elimination of pathogens or activate other cellular components of immunity. NK cells express a broad range of activating receptors and their function is controlled by inhibitory receptors specific for the MHC class I molecules that are ubiquitously expressed on target cells. Several alterations have been described in human NK cell function with advancing ageing, therefore contributing to immunosenescence. Thus whereas healthy elderly, including centenarians, have preserved NK cell number and function, a decrease in NK cell activity is associated to increased incidence of infectious and inflammatory diseases and to increased risk of death due to infection. Here, we describe recent data about the effects of ageing on NK cells.