A radioimmunoassay for measurement and characterization of human antileukoprotease in serum.

This report describes a radioimmunological method for the measurement of the protease inhibitor antileukoprotease in nanogram quantities. Antileukoprotease, previously found in bronchial secretions, has now also been found in serum using this radioimmunologic technique. In healthy blood donors the serum level was 126 micrograms/l. The serum immunoreactive antileukoprotease was found in a free form and did not show any antigenic cross reaction with the normal plasma protease inhibitors. Further, it was also found to be active and to form a complex with active human granulocyte elastase.