Figure 1.

Gene-expression profiles associated with the activation and memory formation of CD8⁺ T cells. (a) Quantification of genes upregulated (Up) or downregulated (Down) in infection-exposed OT-I cells relative to their expression in naive OT-I cells at various time points during infection (horizontal axis). (b) Hierarchical clustering analysis of OT-I cells sorted at various time points after infection with Lm-OVA, filtered for a change in expression of over twofold anywhere in the data set, a coefficient of variation of less than 0.5 and mean expression value of over 120. (c) Ten clusters with the most dynamic expression by K-means clustering analysis, filtered as in b but with a change in expression of over 1.4-fold. Each line represents a single probe; numbers in bottom right corners indicate number of probes; above plots, genes of interest in each cluster. (d) Heat map (bottom) of the correlation coefficients of mean gene expression fit to an artificial exemplar (top) of genes upregulated only at day 45 and day 100 of infection (left) or of genes upregulated only at day 100 (right), showing the top 15% of correlated genes. (e) Quantification of genes in each cluster a given gene ontology (GO) tag related to metabolism (key), presented relative to all genes with that tag. Data are representative of three experiments with a compilation of two (48 h and day 100) or three (all other time points) independent samples sorted from pooled spleens (n ≥ 3 per sample).