FIG. 3.

(A) A CD25⁺CD8⁺ T-cell subpopulation of substantial size is found within the CD45RA⁻ CD28⁺ memory population in elderly persons without CMV infection. This population is decreased in size in elderly persons with latent CMV infection as well as in younger age groups. A representative example of CD25-expressing cells (black dots) superimposed on a double staining of CD45RA and CD28 in gated CD8⁺ cells (gray dots) in the different study groups is shown. (B) The frequency of CD25-expressing cells in CD8⁺ T cells is shown in young, middle-aged, and in elderly persons with (▨) and without (□) latent CMV infection. Bars represent means ± SEM. Significant differences are indicated as follows: *, CMV antibody-negative (Ab⁻) versus CMV Ab⁺ persons; †, young versus elderly; #, middle-aged versus elderly persons without latent CMV infection.