Human CD4⁺ CD25^hi Foxp3⁺ regulatory T cells are derived by rapid turnover of memory populations in vivo
J. Clin. Invest. Milica Vukmanovic-Stejic, et al. 116:2423 doi:10.1172/JCI28941 [Go to this article.]

Figure 1
CD4⁺ CD25⁺ T cells remain functional with age. (A) Freshly isolated PBMCs from younger and older donors were stained with CD4 and CD25 and the percentages of CD25^int and CD25^hi CD4⁺ T cells were determined. Statistical significance was determined by 2-tailed, unpaired Student’s t test. (B) The coexpression of CD25 and Foxp3 in CD4⁺ T cells in older and younger subjects was determined. The left panels show the gating on PBMCs labeled with CD4-PerCP and CD25-PE. Based on CD25 expression, the CD4 population is subdivided into CD25^–, CD25^int, and CD25^hi populations. Histograms illustrate the Foxp3 expression in gated populations (log scale). Filled histograms represent staining with secondary antibody alone. Results are representative of 5 separate experiments performed on younger and older subjects. (C) Purified CD4⁺CD25^– T cells were stimulated with immobilized anti-CD3, purified protein derivative (PPD), and tetanus toxoid in the presence of autologous irradiated PBMCs as APCs. CD4⁺CD25^– T cells were cultured in the absence (black bars) or presence (white bars) of equal numbers of either CD4⁺CD25^– or CD4⁺CD25⁺ cells. Proliferation was measured by ³H-thymidine incorporation on day 3 (for anti-CD3) and day 6 (for recall antigens), and results are expressed as mean ± SEM of triplicate wells. Results shown are representative of 5 experiments performed in younger and older subjects.