Physiological roles of macrophages

Macrophages are present in mammals from midgestation, contributing to physiologic homeostasis throughout life. Macrophages arise from yolk sac and foetal liver progenitors during embryonic development in the mouse and persist in different organs as heterogeneous, self-renewing tissue-resident populations. Bone marrow-derived blood monocytes are recruited after birth to replenish tissue-resident populations and to meet further demands during inflammation, infection and metabolic perturbations. Macrophages of mixed origin and different locations vary in replication and turnover, but are all active in mRNA and protein synthesis, fulfilling organ-specific and systemic trophic functions, in addition to host defence. In this review we emphasise selected properties and non-immune functions of tissue macrophages which contribute to physiologic homeostasis

Measuring Apoptotic Cell Engulfment (Efferocytosis) Efficiency

Efferocytosis is the process of recognizing and removing dead and dying cells, performed by a variety of phagocytic cells including macrophages. It has recently been shown that liver X receptor (LXR) signaling in macrophages regulates the expression of important efferocytosis receptors, bridging and signaling molecules. Here we describe a sensitive yet robust efferocytosis assay, optimized to measure bone marrow-derived macrophage (BMDM) apoptotic cell engulfment capability. This assay can be applied to genetically or pharmacologically altered BMDMs