Inducible IL-2 production by dendritic cells revealed by global gene expression analysis

Dendritic cells (DCs) are strong activators of primary T cell responses. Th eir priming ability is acquired upon encounter with maturation stimuli. To identify the genes that are differentially expressed upon maturation induce d by exposure to Gram-negative bacteria, a kinetic study of DC gene express ion was done with microarrays representing 11,000 genes and ESTs (expressed sequence tags). Approximately 3000 differentially expressed transcripts we re identified. We found that functional interleukin 2 (IL-2) mRNA, which ga ve rise to IL-2 production, was transiently up. regulated at early time-poi nts after bacterial encounter. In contrast, macrophages did not produce IL- 2 upon bacterial stimulation. Thus, IL-2 is an additional key cytokine that confers unique T cell stimulatory capacity to DCs.