Immunological characterization of an arylamidase (aminopeptidase) occurring in histiocytoma.

Histiocytomas display a remarkably strong proteolytic activity. Electrophoretic and immunological studies reveald that this proteolytic activity is due, at least partially, to the presence of an arylamidase, previously described as "aminopeptidase I". This enzyme has been identified in various tissues of ectodermal, mesodermal and entodermal origin.