Monoclonal antibodies against urokinase

Hybridomas secreting antibodies against human urokinase have been produced by the cell-fusion technique (Köhler & Milstein, 1976). They belong to the IgG1 and IgG2 classes. Fixation and inhibition of the binding of 125 I-labelled urokinase, in radioimmunoassay, show that two of the monoclonal antibodies exhibit a high titer in ascitic fluids, a good sensitivity, and no cross reaction with other enzymes showing partial sequence homology with urokinase. Moreover, one of the monoclonal antibodies is able to inhibit the enzymatic activity of urokinase using a chromogenic substrate.