The use of the proteolytic enzyme brinase to produce autocytotoxicity in patients with acute leukemia and its possible role in immunotherapy.

Summary Daily infusion of brinase (Protease 1 of Aspergillus oryzae ) for 10 to 30 days in six patients (three children, three adults) with acute leukemia resulted in the production of complement-dependent autocytotoxicity against leukemic cells and lymphocytes and, in some instances, against platelets. This appeared to be due to the production of autoantibody, but its nature remains to be elucidated. The autocytotoxicity can be demonstrated in vivo by blood transfusion from a healthy donor or in vitro at 37° by Terasaki9s microcytotoxicity test. The autocytotoxicity is transient, lasting from 3 to 15 days, but repeat courses of brinase, whether they are given alone or in combination with antileukemic drugs, produce further autocytotoxic “antibodies.” Remission was obtained in three of five patients who were given combination therapy and in the one patient with acute myeloblastic leukemia who was treated by brinase alone.