PLASMA-CLOT LYSIS INDUCED BY MONOCLONAL ANTIBODY AGAINST α2-PLASMIN INHIBITOR
Authors: Sakata Y , Mimuro J , koike Y 
Published: August 2018

A Monoclonal antibody (MCA) against α2-plasmin inhibitor α2-Pl) designated as JTP-1 inhibited antiplasmin act ivity and complex formation of a2-PI with plasmin. By using this MCA we tried to observe plasma-clot lysis (CL) in vitro and to estimate the level of total fibrinolytic capacity in plasma. As reported previously (Blood 55: U83, 1980) spontaneous CL is a striking feature of the plasma derived from a patient with α2-PI deficiency. We showed that this abnormally increased fibrinolysis was solely due to the deficiency of α2-PI. However, the contribution of plasminogen activator (PA) and its inhibitor to this specific patient' plasma -CL has been under discussion. Therefore, to test whether similar CL can be found in normal plasma without an addition of PA, plasma clots were made after incubation of plasma from normal volunteers containing 125i fibrinogen with various concentration of JTP-1, and fibrinolysis was measured by counting the soluble radioactivity. The addition of JTP-1 to plasma led to a dose-dependent enhancement of the soluble 125i fragment-release from the clot. However, JTP-1 had no effect on a2-PI-deficient plasma-CL. Other anti-a2-PI MCAs whose epitopes were not involved in the reactive site of a2-PI had no effect on CL and rabbit anti-mouse immunoglobulin IgG neutralized this JTP-l-inducing CL completely. Immunodepletion of tissue PA (tPA) or plasminogen from plasma decreased the rate of CL but that of prourokinase did not. To determine the role of PA inhibitor (PAl) released from platelets (pits) in the regulation of CL in vitro, plasma clots were made from pits poor plasma (PPP) and pits rich plasma (PRP), and CL was observed in the presence of JTP-1. There was almost no difference of the lysis time between PPP clot and PRP clot, although plasma clot from pregnant woman was lysed slowly. These results strongly suggest that endogenous t-PA in plasma is still functionally active after blood collection and CL is mainly prevented by a2-PI in vitro.-plasmin inhibitor (a2-Pl) designated as JTP-1 inhibited antiplasmin act ivity and complex formation of a2-PI with plasmin. By using this MCA we tried to observe plasma-clot lysis (CL) in vitro and to estimate the level of total fibrinolytic capacity in plasma. As reported previously (Blood 55: U83, 1980) spontaneous CL is a striking feature of the plasma derived from a patient with a2-PI deficiency. We showed that this abnormally increased fibrinolysis was solely due to the deficiency of a2-PI. However, the contribution of plasminogen activator (PA) and its inhibitor to this specific patient' plasma -CL has been under discussion. Therefore, to test whether similar CL can be found in normal plasma without an addition of PA, plasma clots were made after incubation of plasma from normal volunteers containing 125i fibrinogen with various concentration of JTP-1, and fibrinolysis was measured by counting the soluble radioactivity. The addition of JTP-1 to plasma led to a dose-dependent enhancement of the soluble 125i fragment-release from the clot. However, JTP-1 had no effect on a2-PI-deficient plasma-CL. Other anti-a2-PI MCAs whose epitopes were not involved in the reactive site of a2-PI had no effect on CL and rabbit anti-mouse immunoglobulin IgG neutralized this JTP-l-inducing CL completely. Immunodepletion of tissue PA (tPA) or plasminogen from plasma decreased the rate of CL but that of prourokinase did not. To determine the role of PA inhibitor (PAl) released from platelets (pits) in the regulation of CL in vitro, plasma clots were made from pits poor plasma (PPP) and pits rich plasma (PRP), and CL was observed in the presence of JTP-1. There was almost no difference of the lysis time between PPP clot and PRP clot, although plasma clot from pregnant woman was lysed slowly. These results strongly suggest that endogenous t-PA in plasma is still functionally active after blood collection and CL is mainly prevented by a2-PI in vitro.-plasmin inhibitor (a2-Pl) designated as JTP-1 inhibited antiplasmin act ivity and complex formation of a2-PI with plasmin. By using this MCA we tried to observe plasma-clot lysis (CL) in vitro and to estimate the level of total fibrinolytic capacity in plasma. As reported previously (Blood 55: U83, 1980) spontaneous CL is a striking feature of the plasma derived from a patient with α2-PI deficiency. We showed that this abnormally increased fibrinolysis was solely due to the deficiency of a2-PI. However, the contribution of plasminogen activator (PA) and its inhibitor to this specific patient' plasma -CL has been under discussion. Therefore, to test whether similar CL can be found in normal plasma without an addition of PA, plasma clots were made after incubation of plasma from normal volunteers containing 125i fibrinogen with various concentration of JTP-1, and fibrinolysis was measured by counting the soluble radioactivity. The addition of JTP-1 to plasma led to a dose-dependent enhancement of the soluble 125i fragment-release from the clot. However, JTP-1 had no effect on a2-PI-deficient plasma-CL. Other anti-a2-PI MCAs whose epitopes were not involved in the reactive site of a2-PI had no effect on CL and rabbit anti-mouse immunoglobulin IgG neutralized this JTP-l-inducing CL completely. Immunodepletion of tissue PA (tPA) or plasminogen from plasma decreased the rate of CL but that of prourokinase did not. To determine the role of PA inhibitor (PAl) released from platelets (pits) in the regulation of CL in vitro, plasma clots were made from pits poor plasma (PPP) and pits rich plasma (PRP), and CL was observed in the presence of JTP-1. There was almost no difference of the lysis time between PPP clot and PRP clot, although plasma clot from pregnant woman was lysed slowly. These results strongly suggest that endogenous t-PA in plasma is still functionally active after blood collection and CL is mainly prevented by α2-PI in vitro.