MONOCLONAL-ANTIBODIES AGAINST A RECOMBINANT FORM OF PLASMINOGEN-ACTIVATOR INHIBITOR-1 - EFFECTS ON TISSUE-PLASMINOGEN ACTIVATOR NEUTRALIZING AND VITRONECTIN BINDING-PROPERTIES

A panel of eight murine monoclonal antibodies was produced against a r ecombinant form of plasminogen activator inhibitor-1 (rPAI-1). All the antibodies recognized active and latent forms of rPAI-1, and rPAI-1 c omplexed with tissue plasminogen activator (t-PA) as determined in enz yme-linked immunosorbent assays (ELISA). Three of the antibodies, FAG9 , FAD3 and BBH2, were particularly effective at inhibiting the t-PA ne utralizing activity of rPAI-1 as measured in a chromogenic assay. Thre e different antibodies, DD8E9, FEG7 and FGG7, inhibited the binding of [I-125]rPAI-1 to vitronectin immobilized on polystyrene wells. The co mbination of FGG7 and alkaline phosphatase-labeled BBH2 resulted in a sensitive sandwich ELISA for rPAI-1 with detection limits in the range of 1-10 ng. Definition of epitopes recognized by these antibodies wil l be useful for identifying various domains on PAI-1 involved in its i nteraction with protease substrates and with its protein cofactor, vit ronectin.