Structural heterogeneity of faecal alpha 1 antitrypsin shown by immunoblot analysis in patients with Crohn's disease. Issue 5 (May 1991)

• Record Type: Journal Article
• Authors: Boege, F; Fischbach, W
• Is Part Of: Gut. Volume 32:Issue 5(1991)
• Page Start: 496
• Page End: 499
• Publication Date: 1991-05
• Subjects: Gastroenterology -- Periodicals; 616.33
• DOI: 10.1136/gut.32.5.496
• Languages: English
• ISSNs: 0017-5749

Abstract

Abstract : 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.