Defining Epigenetic Regulation of the Interleukin-9 Gene by Chromatin Immunoprecipitation.

Regulation of gene expression is essential for the differentiation of pluripotent precursor cells into specialized effector cells and, thus, for the evolution of multiorgan systems. The regulation of gene expression is controlled by a variety of "extra-genic" mechanisms, termed as epigenetic mechanisms. Obviously, alterations in such control mechanisms of gene expression may result in alterations of cellular effector functions, resulting in for example defects in cellular functions, but also, if immune cells are involved, leading to the development of immunologic disorders such as malignancies and autoimmune diseases. The analysis of epigenetic modifications is therefore pertinent not only for the understanding of the regular function of the immune system, but also for the understanding of the pathophysiology of such diseases. As interleukin-9 (IL-9) is the signature cytokine for Th9 cells, and since IL-9 plays important roles in the orchestration of a protective immune responses, the analysis of epigenetic mechanisms underlying the development of IL-9 producing effector T cells is of great interest. Here, we describe a protocol to analyze epigenetic regulation of the IL-9 gene by chromatin immunoprecipitation.