Relative specificity for active inflammatory bowel disease of plasma-derived proteins in gut lavage fluid

Abstract

Objective: Whole gut lavage with isotonic non-absorbable fluid is essentially a whole gut perfusion; whole gut lavage fluid (WGLF) can be used for clinical evaluation of intestinal immunity. High concentrations of WGLF immunoglobulin (lg) G, albumin and α-1-antitripsin (A1AT; probably reflecting plasma leakage) are characteristics of active inflammatory bowel disease. We aimed to establish reference values for concentrations of these proteins in WGLF and to assess the extent of high concentrations in conditions other than active inflammatory bowel disease. Methods: Gut lavage was performed on 63 immunologically normal patients or volunteers and on 254 occasions in patients with gastrointestinal symptoms or disease. After filtration and addition of protease inhibitors, WGLF content of IgG was assayed by enzyme-linked immunosorbent assay; albumin and A1AT by immunoturbidimetry. Results: Normal ranges were established: IgG < 1–10 μg/ml; albumin <1–26 μg/ml and A1AT < 1–19 μg/ml WGLF. In 102 tests on patients with inflammatory bowel disease of varying activity, high concentrations of WGLF IgG were present in 64%, of albumin in 52% and of A1AT in 36%. High concentrations of one or more proteins were present in 15 out of 152 patients with other conditions. In the majority, the existence of gastrointestinal protein loss was consistent with the clinical picture (one lymphangiectasia, seven colorectal cancers, one gut lymphoma, one perforated diverticulitis, one pouchitis and one lymphocytic colitis). Conclusion: Studies of gut lavage fluid proteins provide a new approach to screening of clinically complex patients with inflammatory bowel disease and other ulcerating and inflammatory lesions. This simple technique offers an alternative to faecal isotope excretion in the diagnosis of protein-losing enteropathy.