Time-resolved fluoroimmunoassay of human pancreatic phospholipase A2.

We describe an immunofluorometric assay for human pancreatic phospholipase A2 based on time-resolved fluorescence. The labeled antibody technique in combination with the time-resolved 1-s fluorometric detection of the europium label, which essentially eliminates all background fluorescence, resulted in a high sensitivity (20 ng/L) and a wide (5000-fold) linear range. Nonspecific binding was minimized by treating the solid-phase antibody with NaSCN before coating, to remove endogenous antigen, and by immunosorbent purification of the antibody before labeling with europium. This is a one-incubation, multi-site, solid-phase assay on polystyrene microtiter strips, even though a polyclonal antibody was used. As measured by this assay, activity of immunoreactive phospholipase A2 was found to be above normal in sera of patients suffering from acute pancreatitis.