5-chloro-1'-[(2-fluorophenyl)methyl]-2,2',5'-trioxo-spiro[3H-indole-3,3'-pyrrolidine-1(2H)-acetic acid is a potent CRTH2/DP2 receptor antagonist (Ki = 37 nM). The biological effects of prostaglandin D2 (PGD2) are transduced by at least two 7-transmembrane G protein-coupled receptors, designated DP1 and CRTH2/DP2. In humans, CRTH2/DP2 is expressed on eosinophils, basophils and Th2 cells where it mediates the chemotactic activity of PGD2.
