Suppression of in vitro proliferation by TREGs from cord and adult blood and lymph node. (A) Suppression of proliferation of bead selected CFSE-labeled CD4⁺CD25^- cells by unlabeled CD4⁺CD25⁺ TREGs using adult blood or cord blood as the source of both CD4⁺CD25^- and CD4⁺CD25⁺ cells. The bars represent the means ± SEM of 4 to 7 independent experiments. (B) Suppression by flow-sorted populations (1, 2, and 3 as defined in Figure 6A) from cord and adult blood and lymph node. Responder cells were sorted autologous CD4⁺CD45RA⁺CD25^- (population 5), which were also titered in parallel with the other sorted populations. Ratios of suppressor to responder cells are shown on the x-axis. Left panels show thymidine assay; right panels, CFSE assay. Bars represent the mean ± SEM of 2 to 4 replicate cultures from a single experiment. Where no error bars are present, assays were performed in a single culture well. The data for cord and adult blood are representative of 2 to 3 experiments, whereas the lymph node experiment was performed only once.