Inter-alpha-trypsin inhibitor of human serum: an inhibitor of polymorphonuclear granulocyte elastase.

Inter-alpha-trypsin inhibitor (ITI) was separated from human serum in a single step using ion-exchange chromatography via the fast protein liquid chromatographic system. The inhibitor preparation, identified as ITI by specific immunological assays, inhibited human polymorphonuclear granulocytic elastase besides bovine trypsin. Hence, ITI is the third candidate of the plasma proteinase inhibitors (in addition to alpha 1-proteinase inhibitor and alpha 2-macroglobulin) capable of inhibiting lysosomal granulocytic elastase.