Lymphocytes sub-types and functions in centenarians as models for successful ageing

Several cell subsets participate to the immune response, and their close interplay is fundamental for the successful elimination of harmful pathogens. In addition, a tight regulation of the immune response has to occur in order to avoid excessive inflammation and potential autoreactivity towards self components. In the last years, the discovery and the characterization of new lymphocytes subsets, including regulatory T (Treg)-cells and Natural Killer T (NKT)-cells allowed a better understanding of how an effector immune response is induced and therefore down-modulated. During the ageing of the immune system, a process termed immunosenescence, these subsets undergo a profound remodelling, both in phenotype and function. In this chapter, we will describe the essential features of lymphocyte populations in centenarians and the differences that occur with unsuccessfully aged people.