Monoclonal antibody to human tissue plasminogen activator.

Hybridoma producing a monoclonal antibody IgG1 to one-chain tissue plasminogen activator (t-PA) derived from human melanoma cells was obtained by fusion of mouse myeloma cells (SP-1) and spleen cells of mice previously immunized with purified t-PA. The monoclonal antibody reacted only with t-PA derived from the human melanoma cells (Bowes), and not with plasminogen activator purified from porcine heart or from human urine. The monoclonal antibody obtained from mouse ascites demonstrated 50 times stronger antibody activity than that of polyclonal antibody obtained from mouse serum. The monoclonal antibody bound t-PA firmly, inhibited the fibrinolytic activity of t-PA, but did not inhibit the amidolytic activity of t-PA completely. The fibrin-binding ability of t-PA was not inhibited. The binding of monoclonal antibody to the non-reduced form of t-PA did not differ from that to the reduced form of t-PA.