Preparation of samples and experimental procedure. (A) Freshly isolated PBMCs from healthy individuals (naive normal PBMCs) were enriched for CD8⁺ T cells using negative isolation (naive normal enriched CD8⁺ cells) as described in “Methods.” Cells (5 × 10⁷) were activated using 1 μg/mL PHA for 3 days followed by 500 IU/mL IL2 for 7 days (activated normal PBMCs). Following activation, 10⁸ cells were enriched for CD8⁺ cells (activated normal enriched CD8⁺ cells). Percentage of CD3⁺CD8⁺ cells is shown in parentheses. (B) Experimental procedure: The samples were used for RNA isolation and subjected to microarray analysis. LGL leukemia PBMCs were obtained fresh from the patients and were not cultured, sorted, or activated. The samples with similar phenotype were either pooled (pooled sample analysis) or analyzed without pooling (unpooled sample analysis). Genes differentially expressed in both analyses were considered to be differentially expressed.