NK cells during human aging: Increased number of NK lymphocytes associated with normal NK function

A general decline of immune functions, particularly affecting the T cell compartment, has been reported to occur during aging. Some of these observations may be partially explained by a reduction in thymic hormone levels, and an altered proportion amongst the different subsets of T cells responsible for the immune response. On the other hand, the number of circulating B cells and their functional activity seems to be relatively unaffected by aging, although altered immunoglobulin production, such as an increased incidence of paraproteins, has been reported. Whilst there has been a large number of studies related to T cell function, the cytotoxic activity against unrelated tumour cell lines (NK activity) has been only partially investigated in aged subjects.