Histidine-rich glycoprotein is present in human platelets and is released following thrombin stimulation.
Histidine-rich glycoprotein, and alpha 2-glycoprotein in human plasma, has been shown to interact with heparin, with the high-affinity lysine-binding site of plasminogen, with divalent cations, and is associated with the rosette formation between erythrocytes and lymphocytes. A specific enzyme-linked immunosorbent assay for histidine-rich glycoprotein has been developed and used to demonstrate that histidine-rich glycoprotein is present in human platelets. Histidine-rich glycoprotein was detected and quantified in detergent extracts of washed human platelets, with a mean level of 371 ng/10(9) platelets. Plasma histidine-rich glycoprotein, either in the platelet suspending medium or on the surface of the platelets, accounted for less than 3.4% of the detectable platelet histidine-rich glycoprotein. Histidine-rich glycoprotein was also demonstrated in human bone marrow megakaryocytes by immunofluorescence. The extent of histidine-rich glycoprotein release from platelets was dependent on the thrombin dose and correlated directly with the extent of serotonin release. The platelet and plasma histidine-rich glycoprotein were similar by immunochemical analysis. Anti-histidine-rich glycoprotein IgG did not inhibit platelet aggregation. Histidine-rich glycoprotein released by platelets following thrombin stimulation may play a significant role in modulating inflammatory events in the microenvironment of the platelet plug.
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000494:pharmacology; D001792:Blood Platelets / Q000378:metabolism*; D003094:Collagen / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006023:Glycoproteins / Q000097:blood*; D006639:Histidine / Q000097:blood*; D006801:Humans; D008533:Megakaryocytes / Q000032:analysis; D010974:Platelet Aggregation / Q000187:drug effects; D013917:Thrombin / Q000502:physiology*
D001095:Arachidonic Acids; D006023:Glycoproteins; D016718:Arachidonic Acid; D006639:Histidine; D003094:Collagen; D013917:Thrombin