Detection of TCRγ gene expression in NK cells by microarray analysis. (A) Gene expression patterns of purified IL-2–activated adult and neonatal NK cells were analyzed in triplicate using Affymetrix GeneChip Mouse Genome U74Av2 arrays. Expression of α, β, γ, and δ TCR genes ± SD are shown. ▪ indicates neonatal NK cells; □, adult NK cells. The expression values (0-700 on the graph) are based on raw values after default normalization of the 6 chips, with the 3 adult samples grouped together and the 3 neonatal samples grouped together. For Affymetrix gene chips, each gene is represented by a probe set of 10 to 25 oligonucleotide pairs, each pair consisting of a perfectly matching probe and a probe with one nucleotide mismatch in the middle of the sequence. The detection call of whether a gene is present (expressed) or absent (not expressed) is based on binding to the perfect match and mismatch pairs. Therefore, an expression value can be assigned, but it does not necessarily mean the gene will be called present. * indicates that the gene is present and that the expression values are valid. The Affymetrix probe numbers for these genes are β1, 101311; β2, 94202; β3, 99798; α1, 101823; α2, 97944; α3, 97945; pα (preTα), 98354; δ, 92328; γ1, 102745; γ2, 102685; and γ3, 102744. (B) Significant difference in expression levels of TCRγ gene (probe 102744) in IL-2–activated adult NK cells (□) and neonatal NK cells (▪) determined by a 1-way ANOVA (P < .05). The values represent the log ratio, which is the intensity ratio (adult NK cell sample gene divided by the neonatal NK-cell sample gene) log transformed (log₂). Error bars represent the standard deviation.