CELL-MEDIATED-IMMUNITY CHANGES IN AGING, RELATIVE IMPORTANCE OF CELL SUBPOPULATION SWITCHES AND OF NUTRITIONAL FACTORS

Decreased T-cell functions with ageing have been extensively described. This review focuses on recent data on changes in T-cell subpopulations related to ageing and their consequences on T-cell proliferation. Increase of immature T cells CD2(+) CD3(-) is an ageing phenomenon related to T-cell declining proliferation. Recently it was shown that increase of immature T cells was due to an increase in different subtypes of the CD2(+) CD3(-) population, double-negative CD2(+) CD4(-) CD8(-) and double-positive CD2(+) CD4(+) CD8(+) subpopulations, the former being associated with nutritional deficit, the latter with associated diseases. Other authors have focused on decreases of naive T cells with parallel increase of memory T cells; such a switch is also relevant to declining T-cell proliferation. This review focuses on two major factors which influence immune ageing: nutritional parameters and antigen exposure.