Age-related changes in the absolute number of CD95 positive cells in T cell subsets in the blood.
Comparison of the absolute number of cells in distinct T cells subsets expressing CD95 (Fas) was carried out in two populations of healthy female volunteers. In one population, the average age was 30 +/- 5 years, and in the second population the average age was 73 +/- 13 years. No significant difference was noted in the total number of lymphocytes, CD3+, CD4+, or CD8+ cells per microL of blood between the two age groups, but major differences were noted in the number of cells expressing CD95. A significant reduction was seen in the number of cells per microL of blood in both the CD4+ CD45RA+ CD95+ and CD8+ CD45RA+ CD95+ populations in the older group compared with the younger group. Within the memory pool significantly fewer CD8+ CD45RO+ CD95+ cells were found in the older population compared with the younger group. 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 activation, may be implicated as a mechanism by which cells that have reached a stage of replicative senescence remain in the peripheral T cell pool. Anti-CD3-mediated activation of cells from both groups revealed much lower proliferative responses from the older group, supporting the idea that there is an age-associated increase in the number of cells that have reached their replicative limit. These cells may not be lost from the peripheral pool because they fail to express CD95.
Aspinall
R
R
Department of Immunology, Chelsea & Westminster Hospital, London, UK. r.aspinall@ic.ac.uk
Carroll
J
J
Jiang
S
S
D000328:Adult; D000368:Aged; D000375:Aging / Q000276:immunology*; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D018655:Lymphocyte Count; D008875:Middle Aged; D016176:T-Lymphocyte Subsets / Q000502:physiology*; D019014:fas Receptor / Q000032:analysis*
D019014:fas Receptor