Background of the antigen
Plasminogen is a plasma protein synthesised mostly in the liver. Plasma concentration is usually in the range of 70 to 200mg/l. Plasminogen is activated by tissue plasminogen activator, urokinase and streptokinase, to form plasmin. Activation results from the cleavage and release of the preactivation peptide. Angiostatin, an internal fragment of plasminogen, is a potent inhibitor of angiogenesis, which selectively inhibits endothelial cell proliferation. Angiostatin potently inhibits tumor growth and can maintain metastatic and primary tumors in a dormant state. It is defined by a balance of proliferation and apoptosis of the tumor cells and is composed of plasminogen first four cringle structures. This molecule is generated by proteolytic cleavage of plasminogen.
