Oxysterols have recently been identified as natural ligands for a G protein-coupled receptor called EBI2 (aka GPR183)(Nature 2011, 475, 524; 519). EBI2 is highly expressed in immune cells (J. Biol. Chem. 2006, 281, 13199), and its activation has been shown to be critical for the adaptive immune response and has been genetically linked to autoimmune diseases such as type I diabetes (Nature 2010, 467, 460). Here we describe the isolation of a potent ...