Natural killer cells and human longevity

Abstract

Natural killer (NK) cells are a lymphocyte subset in the innate immune system. These cells not only mount an early immune response to infections and neoplasia but also affect the adaptive immune system by communicating with dendritic cells. In this chapter, we review basic findings on NK-cells and then information from 1) rare patients with isolated NK-cell deficiency, 2) patients with certain malignant neoplasia, and 3) healthy middle-aged and elderly individuals. Those findings indicate that NK-cells are crucial immune components for sustaining life. With increasing age, numbers of T- and B-lymphocytes decline while the number of NK-cells increases. This is especially marked in centenarians. In terms of reduced tolerance to stress such as infections in the elderly, the power of early responders in the immune system including NK-cells may be especially important.