Inhibition of the Elastase-Like Esterase in Human Leukocyte Granules by Human Leukocyte Cell Sap

Human leukocyte cytosol inhibits esterolysis of a synthetic elastase substrate by human leukocyte granule extract. Hydrolysis of the same substrate by pancreatic elastase is not affected, nor is esterolysis of BAPA by trypsin or GPANA by chymotrypsin. Cytosol gives no cross reaction with antisera to human alpha1 trypsin inhibitor or alpha2 macroglobulin, even though cytosol protein is more potent than serum protein in suppressing leukocyte granule hydrolytic activity. The cytosol inhibitor appears to be nondialyzable, thermolabile, and TCA-precipitable. Treatment of cytosol with pronase causes loss of inhibition which is approximately equivalent to the degree of protein digestion in the cytosol. No evidence was obtained for DNA, RNA, or hexuronic acid-containing substances being responsible for inhibition by cytosol.