Figure 3. Effect of age on gene expression in leukocytes recovered from dorsal air pouches raised on WT mice. Gene mRNA transcripts were quantitated as described in Methods and categorized as transcription factors, receptors, cytokines or enzymes. In each category, genes are ranked from the largest increase to the largest decrease under basal conditions (saline injection only). (A) 6-month to 3-month age comparison. (B) 15-month to 3-month comparison. “Stimulation index” is the change due to stimulation by LPS injection, relative to the basal condition. Dotted lines indicate one doubling or halving of gene expression. Values are expressed as the base-2 logarithm.