The liaison between apoptotic cells and macrophages--the end programs the beginning.

The efficient execution of apoptotic cell death with the clearance of apoptotic debris by phagocytes is a key regulatory mechanism ensuring tissue homeostasis. Failure in this execution program contributes to the pathogenesis of many human diseases. In this review, we describe the current knowledge regarding the interaction of apoptotic cells with their professional 'captors', the macrophages, with special emphasis on the immunological outcome. Removal of apoptotic cells must be considered as a process that actively delivers signals to polarize macrophages, which are fundamental for the resolution of inflammation. However, the sculpting of macrophage responses by apoptotic cells can be misused under certain inflammatory disease conditions, including tumor development.