Regulation of the Perforin Locus by IL-2 During CD8+ T-cell Differentiation (35.49)

Abstract

Abstract The molecular basis of memory and effector CD8+ T cell differentiation is not well understood. Here, we show that the strength of IL-2 signaling determines the transcriptional profile of primary mouse cytotoxic T lymphocytes (CTL) during in vitro differentiation. CD8+ T cells were activated and cultured in either high or low dose IL-2 for 1 week; both groups proliferated equivalently and expressed similar amounts of IFNγ upon restimulation. However, cells cultured in high IL-2 maintained phosphorylated Stat5 throughout differentiation, induced the transcription factor Eomesodermin, expressed robust amounts of perforin and granzyme B and displayed a surface phenotype characteristic of effector cells. In contrast, cells cultured in low IL-2 expressed low amounts of granzyme B, reverted to a surface phenotype characteristic of memory cells and gradually silenced expression of perforin mRNA. DNase I hypersensitivity mapping showed no major differences in chromatin structure in >200 kb surrounding the perforin gene, whereas chromatin immunoprecipitation assays showed that cells cultured in high IL-2 displayed increased density of RNA polymerase II at the perforin promoter. Based on these studies in vitro, we propose that the strength of signaling through the IL-2 receptor regulates commitment to the memory cell lineage in vivo.