Immunochemical localization of proteins in the intestinal mucosa of children with diarrhea.

Chronic diarrhea in children is a common and often frustrating problem confronting allergists, pediatricians, and gastroenterologists. We know very little about the mechanism and immunology of this problem. This study used an immunoperoxidase staining technique to evaluate the small bowel biopsy specimens of 15 children with chronic diarrhea. Ten children had diarrhea related to a specific food ingestion, and five had prolonged diarrhea without identification of an offending food. The new finding was the deposition of stain beneath the mucosal cells in the area of the basement membrane of the small bowel mucosa. Anti-IgG and anti-bovine serum albumin (BSA) were the antibody reagents most often associated with the detection of tissue deposits. Deposits of stain were found when the inflammatory system was active as determined by the presence of increased numbers of inflammatory walls in the mucosa.