Value of determination of kininase II in bronchoalveolar lavage fluid

Kininase II (KII), identical with angiotensin-I-converting enzyme (E.C. 3.4.15.1) was characterized biochemically and assayed fluorimetrically in bronchoalveolar lavage fluid and serum of 153 patients with several pulmonary disorders. The albumin concentrations of serum and bronchoalveolar lavage fluid (BLF) have also been measured. The pH optimum of KII derived from BLF (LKII) was 8.0. The Michaelis Menten constant was 38.5 mumol/l using benzyloxycarbonyl-phenylalanyl-histidyl-leucine as synthetic substrate. LKII could be inhibited between 80 and 100% by EDTA, phenanthroline, dimercapto-1-propane-sulfonic acid (DMPS), hydroxyquinoline and captopril. The LKII activity (mU/ml BLF) showed no differences in all lung diseases, but the specific LKII (mU/mg albumin) was significantly elevated in sarcoidosis compared to pneumonia (p less than 0.05), fibrosis (p less than 0.05), chronic obstructive bronchitis (p less than 0.005) and lung cancer (p less than 0.01), but not in tuberculosis. This study shows that LKII is measurable in native, unconcentrated BLF and the results indicate that LKII could be useful for diagnosis of pulmonary disorders.