Age-related acquisition of CD95^high (memory T cell) phenotype is similar in both CD4 and CD8 cells, but CD95^highCD28^– subpopulation accumulates with age only in the CD8 T-cell subset. The percentage of total splenic T cells within CD4 (A) and CD8 (B) T-cell subset expressing CD95^high memory phenotype or CD95^highCD28^– effector-memory phenotype (C) was determined from FCM staining profiles as shown in Figure 1, and values were plotted against the age for each animal.