Flow Cytofluorometric Analysis of the Urokinase Receptor (uPAR) on Tumor Cells by Fluorescent uPA-ligand or Monoclonal Antibody #3936

Quantitative assessment of the interaction of cell surface receptors with their ligands is mainly based on measurements using radiolabeled or fluorescent ligands. The investigation of the dynamics of the ligand-receptor interaction can easily be followed by binding of fluorescent ligands or monoclonal antibodies to surface receptors and quantitation of cell-associated fluorescence by laser-based flow cytofluorometry. The receptor for the plasminogen activator urokinase (uPAR) on normal cells and on tumor cells is a prominent example to study the dynamics of ligand-receptor interaction. We describe quantitative flow cytofluorometric techniques, applying the urokinase ligands FITC-pro-uPA or FITC-HMW-uPA and the monoclonal antibody (mAB) #3936, which allow to determine uPAR antigen on the surface or inside of a variety of normal blood cells and of tumor cells.