Faecal alpha 1 antitrypsin was determined in 34 patients with Crohn's disease and in 19 healthy subjects by immune nephelometry. A structural analysis of faecal alpha 1 antitrypsin was carried out using immunoblot analysis under non-reducing conditions. Native serum alpha 1 antitrypsin migrated with an apparent molecular weight of 45 kDa. Proteolytic alpha 1 antitrypsin fragments (5-42 kDa) were specifically immunostained in 13/19 and 22/34 stool samples from control subjects and from patients with Crohn's disease respectively. There was a weak correlation (r = 0.47; p less than 0.02) between the molecular weight of fragmented alpha 1 antitrypsin and the faecal concentration in both groups, indicating that alpha 1 antitrypsin inhibits its own proteolysis by intestinal proteases in a dose dependent way. The incidence of polymeric forms (greater than 45 kDa) was similar in patients (10/34) and control subjects (5/19). In only one case in each group was the native serum form of alpha 1 antitrypsin found in faeces. We conclude that faecal alpha 1 antitrypsin differs structurally from the native serum form. Immunochemical measurements, therefore, reflect rather than represent faecal concentrations of alpha 1 antitrypsin. The controversial results in published reports may be partly explained by these findings. The molecular heterogeneity of faecal alpha 1 antitrypsin is not specifically associated with Crohn's disease.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.