MOLECULAR-DISTRIBUTION OF ELASTASE BETWEEN ITS 2 MAIN INHIBITORS - DIRECT QUANTITATION OF ELASTASE-ALPHA-2-MACROGLOBULIN COMPLEX WITH A NOVEL ELISA TECHNIQUE

A novel enzyme-linked immunosorbent assay for the quantitation of elastase linked to α2-macroglobulin (α2M) (elastase-a2M complex, EMC) in body fluids is presented. The assay has a lower detection limit of 1.5 ng bound elastase per ml. The critical factor allowing immunological detection of α2M-bound elastase is the addition of phenyl methyl sulphonyl fluoride (PMSF) to the assay buffer. The assay has been used to quantitate EMC in plasma and serum of healthy volunteers, and assess the distribution of elastase between its two main inhibitors, α2M and arproteinase inhibitor (API). EMC levels in serum samples from volunteers were significantly higher than in plasma (26.9 vs 21.9 ng/ml, p=0.05, Student's t-test for paired samples). The API-bound elastase levels were 70.2 and 170.1 ng/ml in plasma and serum respectively (statistically significantly higher in serum, p<0.0001). The ratio of macroglobulin to arproteinase-bound elastase levels was 0.333 in plasma and 0.168 in serum (p<0.0001). As α2M bound elastase retains some proteolytic activity, direct measurement of circulating levels in inflammatory conditions should be of interest. © 1990 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.