Immunohistochemical study of enteric nervous system after small bowel transplantation in humans

The neurohormonal structures of two human intestines removed due to rejection 22 months and eight months after intestinal transplantation were studied by an indirect immunohistochemical method and compared with normal ileum. The distribution and density of neurons immunoreactive for tyrosine hydroxylase, substance P, calcitonin gene-related peptide, neuropeptide Y, vasoactive intestinal peptide, galanin, gastrin-releasing peptide, L-enkephalin, and somatostatin were examined. Mucosal endocrine cells immunoreactive for somatostatin, peptide YY, and glucagon were also examined. Extrinsic adrenergic fibers and perivascular fibers were absent in all intestinal layers of the failed grafts. The distribution of intrinsic neurons was unchanged; however, the density was decreased by one rank. Distribution of endocrine cells of the first graft was similar to the normal. Extrinsic fibers were not detected by immunohistochemistry in human small intestinal grafts following long-term survival and eventual rejection, while the immunohistochemical expression of intrinsic neural and endocrine transmitters were well preserved.