Histone Acetylation at the Single-Cell Level: A Marker of Memory CD8+ T Cell Differentiation and Functionality

Abstract

Following stimulation, memory T (TM) cells rapidly express many effector functions, a hallmark feature that allows them to provide protective immunity. Recent studies suggest that genes involved in this rapid recall response may maintain an open chromatin structure in resting TM cells via epigenetic modifications. However, these studies have mostly focused on a few loci, and the techniques used required a large number of cells. We have developed a flow cytometric assay measuring histone modifications in individual murine T cells in combination with lineage-specific markers. In this study, we show that the per-cell level of a marker of open chromatin, diacetylated histone H3 (diAcH3), increases as naive CD8+ T cells develop into TM cells, demonstrating a novel correlation between the differentiation state of a CD8+ T cell and its abundance of a specific histone modification. Furthermore, our results show that TM cells defective in rapid recall ability have less diAcH3 than their fully functional counterparts, indicating that the diAcH3 level of individual TM cells is a useful marker for assessing their functionality.