R. Aspinall et al., AGE-RELATED-CHANGES IN THE ABSOLUTE NUMBER OF CD95 POSITIVE CELLS IN T-CELL SUBSETS IN THE BLOOD, Experimental gerontology, 33(6), 1998, pp. 581-591
Comparison of the absolute number of cells in distinct T cells subsets
expressing CD95 (Fas) was carried out in two populations of healthy f
emale volunteers. In one population, the average age was 30 +/- 5 year
s, and in the second population the average age was 73 +/- 13 years, N
o significant difference was noted in the total number of lymphocytes,
CD3(+), CD4(+). or CD8(+) cells per mu L of blood between the two age
groups, but major differences were noted in the number of cells expre
ssing CD95. A significant reduction was seen in the number of cells pe
r mu L of blood in both the CD4(+) CD45RA(+) CD95(+) and CD8+ CD45RA() CD95(+) populations in the older group compared with the younger gro
up. Within the memory pool significantly fewer CD8(+) CD45RO(+) CD95() cells were found in the older population compared with the younger g
roup. No such difference were found in the number of CD4(+) CD45RO(+)
CD95(+) cells between groups. Such a significant decline in the number
of CD95(+) cells, whose expression is known to be linked with activat
ion, may be implicated as a mechanism by which cells that have reached
a stage of replicative senescence remain in the peripheral T cell poo
l. Anti-CD3-mediated activation of cells from both groups revealed muc
h lower proliferative responses from the older group, supporting the i
dea that there is an age-associated increase in the number of cells th
at have reached their replicative limit. These cells may not be lost f
rom the peripheral pool because they fail to express CD95. (C) 1998 El
sevier Science Inc.