1. Heparin and heparan sulphate strongly inhibited human leucocyte elastase activity in an automated assay using the soluble substrate, n-succinyl-(L-alanine)3-p-nitroanilide (50% inhibition of 250 microliters of 10 micrograms of human leucocyte elastase/ml was obtained with 80 microliters of 2.8 micrograms of heparin/ml and 8 micrograms of heparan sulphate/ml). Less significant inhibition at the same concentrations was seen with the other glycosaminoglycans tested: hyaluronic acid and chondroitin sulphates A-C. 2. Heparin and heparan sulphate also strongly inhibited human leucocyte elastase activity towards insoluble human lung elastin, as determined by an e.l.i.s.a. for soluble elastin-derived peptides released by elastolytic activity on the elastin. This inhibition was shown not to be due to a direct interference of the glycosaminoglycans in the e.l.i.s.a. nor to the inhibition causing a change in the size of the elastin-derived peptides. However, unlike the chromogenic assay with n-succinyl-(L-alanine)3-p-nitroanilide as substrate, where heparin was the more effective inhibitor, in this assay system heparan sulphate was the more effective inhibitor (50% inhibition of 100 microliters of 50 ng of human leucocyte elastase/ml was obtained with 100 microliters of 4.5 micrograms of heparin/ml and 0.8 microgram of heparan sulphate/ml). These results suggest that heparin and heparan sulphate, as components of cellular and basement membranes, are likely to have a role in protecting structural proteins, such as elastin, from the proteolytic activity of human leucocyte elastase.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary emphysema is likely to be the result of elastic tissue digestion by unrestrained elastase activity in the lung. Elastin breakdown by elastases results in the release of soluble elastin fragments (EDP), which may be measured in plasma by an ELISA. Plasma EDP levels measured using an ELISA were determined in the following groups: disease-free children (n = 24), 0.162 +/- 0.082 ng/ml; disease-free adult nonsmokers (n = 114), 1.74 +/- 0.8 ng/ml; smokers (n = 68), 2.76 +/- 4.59 ng/ml; reformed smokers (n = 43), 1.91 +/- 1.14 ng/ml. Adults with established pulmonary emphysema (n = 50), as defined by bullous formation on the chest radiograph, had levels of 50.83 +/- 24.8 ng/ml, significantly higher than the disease-free groups at p < 0.01. Pulmonary emphysema can be reflected by pulmonary function tests, especially those that measure the pulmonary elastic properties, and by computed tomographic (CT) scan percent emphysema score. We therefore examined the relationship of plasma EDP to these other indicators of pulmonary emphysema in a separate group of 26 subjects using elastic recoil measurements (K), and a further group of 30 subjects with CT scan percent emphysema score. A significant correlation of p < 0.001 was shown for plasma EDP and K and a significant correlation of p < 0.01 was shown for plasma EDP and CT scan percent emphysema score, these correlations suggesting that plasma EDP levels are indicators of the loss of pulmonary distensibility and of mild to moderate pulmonary emphysema. These findings suggest that pulmonary emphysema is characterized by active elastin breakdown.

No abstract

We evaluated 10 microfilters for their ability to filter diluted sera without removing immunoglobulins (Ig) G, A, and M, albumin, and transferrin. In general, filters containing cellulose nitrate remove IgG from solution, the amount adsorbed being proportional to the IgG concentration in the solution. With some sera we noted IgA and IgM adsorption to cellulose-nitrate-containing filters, but there was no significant adsorption of albumin or transferrin to any of the filters. We also found that cellulose-nitrate filters adsorbed IgG from antiserum, with consequent loss of titre as seen in a nephelometric assay. Adsorption of IgG was not seen if the filters were prewashed with polyethylene glycol or if the antisera contained polyethylene glycol. With a sufficiently large antibody excess in the nephelometric assay, this loss of titre through filtration becomes undetectable.

No abstract