V alpha 24(+) NKT cells are decreased in elderly humans

Natural killer T (NKT) cells represent a novel cell lineage characterized by the restricted expression of an invariant TCRalpha chain encoded by Valpha24/JalphaQ gene segments in humans and Valpha14/Jalpha281(+) in mice. Different aspects of the immune response are severely affected by age. Thus, we have studied the effect of aging on NKT cells from healthy elderly individuals. Our results demonstrated a decreased percentage of CD3(+)Valpha24(+) cells in peripheral blood from elderly donors, whereas mainstream T lymphocytes showed an age-associated decrease in the expression of CD28, the vast majority of CD3(+)Valpha24(+) cells from old individuals were CD28(+). A significant increase in the percentage of Valpha24(+) cells with the CD4(-)CD8(+) phenotype was also found in the elderly, indicating a redistribution of Valpha24(+) subsets according to the CD4/CD8 phenotype. Given the important immunoregulatory role of these cells, the decrease of NKT cells will contribute to the deleterious immune response in the elderly. (C) 2002 Elsevier Science Inc. All rights reserved.