Effect of human urinary trypsin inhibitor on granulocyte elastase activity.

A human urinary trypsin inhibitor preparation, MR-20, strongly inhibited granulocyte elastase activity. The concentration of MR-20 causing 50% inhibition of the hydrolysis of Suc(Ala) 3pNA by granulocyte elastase was estimated to be 6.4 X 10(-8) M (11 U/ml).