Age-related changes in the expression of CD95 (APO1/FAS) on blood lymphocytes

Aging is associated with alterations of the immune system, thought to be re lated to an increased susceptibility to infectious diseases, and possibly t o cancer and autoimmunity in the elderly. In the present paper we report da ta obtained on freshly collected blood from 148 healthy subjects of differe nt ages (from cord blood to 102 years old). The subjects were divided into seven age classes (cord blood, 3-11 years, 15-39 years, 41-60 years, 61-74 years, 75-84 years, 85-102 years) and their lymphocyte subsets and the expr ession of the apoptosis-related molecule CD95 were evaluated. In respect of lymphocyte subsets, the major differences were found in the cord-blood sam ples compared with the oldest old groups. In the cord-blood group, the abso lute number of all the lymphocyte subsets was enhanced, but in the oldest g roup, an increase of CD16+ lymphocytes was observed, whereas CD19+ lymphocy tes, which progressively decrease with age, continue to decrease further in the very old. The data show that the expression of CD95 increases until ag e 74 years, whereas in the oldest old it, tends to decrease again. The tren d of CD95 expression seems to be related to the change of expression of CD9 5 on CD4+ lymphocytes, because the CD8+/CD95+ population rose steadily thro ughout the entire age range. The evaluation of CD95+/CD45R0+ lymphocytes sh ows similar results to those observed analyzing CD95 on total lymphocytes, Furthermore, a constant increase of CD95+/CD28+ and a related decline of CD 28+ lymphocytes was observed in all age groups. These data suggest that the expression of CD95 on the different subsets of lymphocytes can be consider ed a good marker for studies of immunosenescence, because it may be predict ive of successful aging, and can partially explain the change in lymphocyte s subsets in elderly. (C) 1999 Elsevier Science Inc. All rights reserved.