Gray platelet syndrome (GPS) is an alpha granule deficiency typically characterized by large platelets, mild to moderate thrombocytopenia, and bleeding caused by homozygous or compound heterozygous mutations in the NBEAL2.
When released, alpha granules, dense granules, and lysosomes secrete their contents to assist in the adhesion of segregation of platelets.
A platelet alpha granule
membrane protein that is associated with the plasma membrane after activation.
While sCD40L and sPS are platelet function markers from membrane glycoproteins group, BT and PF4 are alpha granule chemokines.
P-Selectin is an adhesion molecule found in the Weibel- Palade bodies of endothelial cells and the alpha granules of platelets.
For example, the alpha granule
components, beta thromboglobulin and platelet factor 4.
Disorders related only with alpha granule
storage pool include grey-platelet syndrome, Quebec platelet disorder and arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome.
Flow cytometry studies have shown increased surface P-selectin, but decreased alpha granule
The alpha granule
storage pool disorder with large platelets is known as
10) The granule membranes contain many integral glycoproteins on their inner leaflet, such as P-selectin (CD62p) in the alpha granule
and gp53 (CD63) in the lysosome, which become expressed on the outer platelet membrane after the release reaction.
A possible explanation for this is that FV, in addition to circulating in plasma, is stored in platelet alpha granules
and is protected from circulating inhibitors.
For example, PLT alpha granules
, whose contents are released into the vascular space following PLT activation, are rich in many important mediators of hemostatic and nonhemostatic processes, such as procoagulants factor V and von Willebrand factor, mitogens like PLT-derived growth factor, other cytokines such as RANTES (chemokine ligand 5; regulated on activation, normal T cell expressed and secreted), immunoglobulins, and antimicrobial proteins.