Segmental small intestinal allografts in the dog. I. Morphological and functional indices of rejection.

Fourteen dogs received an orthotopically vascularized allograft of a 100-cm length of terminal ileum as a Thiry-Vella segment. Absorption, motility, myoelectrical activity and morphology of the allograft were studied to determine the most reliable indices of rejection. The earliest histological evidence of rejection occurred at a mean of 6.2 +/- 0.9 days and was coincident with significant deterioration in the absorption of water, alanine, lauric acid, sodium, and glucose. Intestinal motility did not decrease until 7-8 days after transplantation, and intestinal myoelectrical activity was unchanged for a further 2-3 days, by which time graft necrosis was imminent. Reduced intestinal motility occurs only after rejection is established, and is therefore of little use as an index of rejection, while recording intestinal myoelectrical activity is valueless and serves only to confirm graft death. Decreased intestinal absorption of water, sodium, glucose, alanine, and lauric acid are present as early as the first changes in mucosal histology and are useful indices of rejection of intestinal allografts.