FIGURE 3. Depletion of CD25^hiCD4⁺ T cells from the blood of elderly individuals increased CD4 T cell function.

5 × 105 CFSE-labeled total CD4⁺ or T_reg-depleted CD4⁺ (CD25-CD4⁺) T cells from 7 elderly individuals (≥ 70-year old) were cultured with 2 × 10⁵ autologous CD14⁺ monocytes and 2 μg/ml PHA for 3 days. (A) Percentage of FOXP3⁺ cells before CD25^hi depletion (Total CD4⁺, left) and after CD25^hi depletion (T_reg-depleted CD4⁺, right). The values from the same subject are linked by a line. Group A is composed of the 4 individuals in whom T_reg depletion led to increased proliferation, whereas group B comprised the 3 individuals who exhibited no increase in proliferation after PHA stimulation. The percentage of FoxP3⁺ cells following CD25 depletion was determined in all subjects, except subject X. (B) CFSE dilution and (C) the expression of CD69 and CD95 markers were analyzed by flow cytometry on gated CD4⁺CD3⁺ T cells. Percentages of dividing cells (CFSElow, corresponding to cells that have divided at least once), in total or T_reg-depleted CD4⁺ T cells, are shown in (B). Percentages of CD69⁺ and CD95⁺ cells, in total or T_reg-depleted CD4⁺ T cells, are shown in (C). Each individual is represented by the same symbol in panels (A), (B) and (C).