Baseline differences between the transcriptional profiles of CD4 and CD8-expressing T cells obtained from 3 Chinese (D12, 15 and 36) and 3 Caucasian (D38, 43 and 45) donors. T cell subsets were separated by negative bead separation (Miltenyi Biotech, Bergisch Gladbach, Germany) at the time of thawing before exposure to 300 IU/ml rIL-2 (referred here simply as CD4 or CD8 T cells, orange and dark blue horizontal bars respectively) or after in vitro culture with or without rIL-2 for four hours (referred here as PPBMC/CD4 or PBMC/CD8; red or light blue horizontal bars respectively). Analysis of significance is based on a paired two-tailed Student t test with a cut off p2-value < 0.05 comparing the combined CD4 and PBMC/CD4 samples to the respective CD8 and PBMC/CD8 samples not stimulated with rIL-2 (No Stim); Data from samples exposed to rIL-2 (rIL-2) are also shown. Selected genes with known immune function are shown in this clusterogram (see text for details). The dashed vertical line separated CD4 from CD8 T cell samples. Ratios are displayed according to the central method for display using a normalization factor .