Characterization of various antibodies against tissue plasminogen activator using highly sensitive immunoassay.

Polyclonal and monoclonal anti-tissue plasminogen activator (t-PA) antibodies were characterized by using enzyme immunoassay (EIA) in which β-D-galactosidase was coupled to anti-t-PA antibody (Fab'). 2:2 B10 and 1:3 G5 antibodies, specific for both one-chain and two-chain t-PA, strongly bound with one-chain t-PA purified from cultured melanoma cell lines, but 1:3 C5 antibody bound weakly with such t-PA. When polyclonal t-PA antibody was used as the first reaction antibody immobilized on silicone pieces, anti-t-PA polyclonal antibody mainly reacted with 2:2 B10 or 1:3 C5 antigenic determinant. When t-PA levels in the plasma were determined, the presence of EDTA enhanced the sensitivity of t-PA determination by the present EIA technic. 2:2 B10 monoclonal antibody detected a part of t-PA molecules in the plasma that polyclonal antibody detected. T-PA was mainly detected in the endothelial cells, but not in the muscular layer of inferior mesenteric artery when immunochemical technic was used where polyclonal t-PA antibody was applied.