Hematopoietic Prostaglandin D Synthase/HPGDS: ProductsProstaglandin D Synthase (PGDS) catalyzes the conversion of prostaglandin (PG) H2 to PGD2, which is a major prostanoid produced in a variety of tissues. Two types of PGDS have been isolated: the glutathione-dependent hematopoietic PGDS (HPGDS) and the glutathione-independent lipocalin type PGDS. HPGDS is a cytosolic enzyme that is expressed in mast cells and antigen presenting cells. It is the only mammalian member of the class Sigma glutathione S transferase, showing a broad specificity towards standard transferase substrates. The PGD2 produced by HPGDS is involved in many physiological processes such as maintaining body temperature, promotion of sleep, inhibition of platelet aggregation and bronchoconstriction. It also functions in immune response and acts as a mediator in allergy and inflammation. HPGDS specific inhibitors may be therapeutically useful anti-allergic and anti-inflammatory drugs.