Differences in expression of genes associated with T-cell activation between circulating and IVS CD8⁺ T cells. Significant differences in individual gene expression (unpaired, two-tailed Student t test; P₂ < .001) between circulating (A) and IVS-induced (B) CD8⁺ T cells. Statistical analysis was performed comparing 10 circulating lymphocyte samples with 11 IVS samples. Because 3 samples from circulating CD8⁺ T cells clustered with IVS-induced T cells (Figure 3C), a third group (C) was analyzed separately. Genes that were differentially expressed between group A and B (total of 761) were subdivided into 2 groups: one included genes specifically expressed in group B (unpaired, two-tailed Student t test; P₂ < .05 between A and C) and one included genes commonly expressed between groups B and C (unpaired, two-tailed Student t test; P₂ < .05). Genes associated with T-cell activation or functions are shown. As a comparison, on the right panels, the transcriptional profile of purified circulating cell subsets including CD4⁺, CD8⁺ memory, CD8⁺ effector T cells, and NK cells is shown ex vivo or after in vitro IL-2 conditioning.