Chromatin Immunoprecipitation in Macrophages.

Macrophages are highly polymorphic depending upon their cellular origin and their tissue environment. The different forms that a macrophage can adopt fundamentally reflect different transcription patterns. In addition, macrophages are exquisitely sensitive to a wide variety of signals coming from either infectious agents or damaged tissues. Most of the responses to these signals involve rapid and massive modifications of transcription. The control of transcription relies on the one hand on the posttranslational modification of histones, and on the other hand on the binding on the chromatin of multiple protein complexes. Immunoprecipitation of cross-linked chromatin with specific antibodies will allow to identify the DNA regions bound by the targeted protein, or carrying the targeted histone modification. By taking a snapshot of the macrophage chromatin composition, this technique will be useful to address specific macrophage biology questions at the DNA level, but also to tackle fundamental problems in transcriptional control in a highly suited model cellular system. In this chapter we describe a protocol of chromatin immunoprecipitation in murine bone marrow-derived macrophages that can easily be adapted to other macrophage populations.