Radioimmunoassay of urokinase for quantification of plasminogen activators released in ovarian tumour cultures

A radioimmunoassay was developed with an urokinase antiserum and radioiodinated DFP-inactivated urokinase of 31,000 daltons. Assays of tissue culture medium from ovarian tumours and fetal kidneys showed the presence of urokinase-like immunoreactivity, which could be separated in three molecular forms at gel filtration. All three forms showed inhibition curves parallel to that of purified urokinase. The concentration obtained by the assay corresponded to the enzymatic activity. Distinctly parallel curves were found for tumour cultures of various ages in which the three molecular forms differed in their relative concentrations.