Human haptoglobin: an endogenous inhibitor of prostaglandin synthase
Human blood plasma haptoglobin (Hp) is a well-characterized glycoprotein present in the α2-globulin fraction of most mammalian plasma or serum. The most characteristic property of Hp is to bind haemoglobin (Hb) stoichio-metrically and irreversibly. Several good reviews9,17 have appeared on the chemistry and physiology of Hp. but its exact physiological function still remains uncertain. It is well known that Hp levels in the serum vary greatly in different conditions. It is usually elevated in inflammatory conditions and acute infections, but depressed in severe chronic liver disease and certain haemolytic conditions7. For the past few years we have been studying the inhibition of prostaglandin (PG) biosynthesis by human blood plasma or serum7,14. These studies demonstrated that Hp potently inhibits PG synthesis. This finding suggested that the biological function of Hp may be associated with the inhibition of PG synthesis in vivo. We have therefore evaluated the effects of purified Hp on several test systems used to study PG synthase inhibitors.
KeywordsArachidonic Acid Acetyl Salicylate Standard Assay Mixture Dexamethasone Sodium Phosphate Hydrocortisone Sodium Succinate
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