Diadenosine 5 ’ , 5 ” - p 1 , p 4 - Tetraphosphate Deficiency in Blood Platelets of the Ch # { 233 } diak - Higashi Syndrome

Diadenosine tetraphosphate (AP4A) is an unusual nucleotide found in a variety of cells. including platelets. It has been suggested that platelet AP4A is stored in the dense granules and is metabolically inactive. We have studied the AP4A content of blood platelets in two patients and three cattle with Ch#{233}diak-Higashi syndrome (CHS). a hereditary platelet defect with dense granule deficiency. Acid-soluble extractions of whole blood and platelets were neutralized. The adenosine triphosphate (ATP) level was measured by luminescence technique. To measure the AP4A content. the neutralized extract was treated with phosphomonoesterase for removal of ATP. The AP4A content was then measured by coupling the phosphodiesterase and luciferase reaction. The AP4A content was 0.43 nmol/mg protein