Brush border enzymes in evaluation of acute small bowel rejection.

The change in activity of three disaccharidase enzymes (maltase, sucrase and lactase) was determined according to the method of Dahlqvist during acute rejection in non-immunosuppressed piglet small bowel grafts. In addition, two brush border enzymes, lactase and aminopeptidase, were stained with monoclonal antibodies. Diminishing disaccharidase activity was an early event during rejection. Diminution began 2 days before distinct morphological changes were seen in the mucosal biopsies. Evaluation of disaccharidase activity can thus be used as a confirmatory method in detecting rejection. Reduction in immunohistological staining of lactase and aminopeptidase with monoclonal antibodies and changes in mucosal morphology were observed to progress simultaneously.