Qualitative study of fecal α₁-proteinase inhibitor in normal subjects and patients with Crohn's disease

We applied sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting to analyze fecal α₁-proteinase inhibitor (α₁PI) from healthy subjects and patient with Crohn's disease. A component with M(r) 38,000 was characterized in normal fecal extracts as well as in six pathological samples. In these cases, the Crohn's disease activity index (CDAI), a clinical index of severity of the disease, was 170 (SEM 47). In contrast, α₁PI of M(r) 51,000 was detected in fecal extracts from eight patients with active Crohn's disease (CDAI = 287, SEM 39). We conclude that fecal α₁PI can be considered a marker of intestinal disease activity.