NUMBER OF SEROTONIN POSITIVE CELLS AND ACUTE CELLULAR REJECTION IN THE EARLY PERIOD AFTER SMALL BOWEL TRANSPLANTATION IN PIGS

Background. Small bowel transplantations (SBT) are being increasingly performed to treat patients with irreversible intestinal failure or short-bowel syndrome. Histologic evaluation of small bowel allograft biopsies is important for the diagnosis of acute cellular rejection (ACR). Serotonin (5-hydroxytriptamin) is a biogenous amine of which up to 95% is present in the enterochromaffin cells of the gastrointestinal tract. The aim of our study was to analyze rejection and number of serotonin positive cells in the intestinal graft biopsy samples early after SBT in pigs. Material and methods. 24 pigs were used and divided into 4 groups. Group A, autologous SBT (n = 3) as a control group; group B, allogeneic SBT with tacrolimus monotherapy (n = 7); group C, allogeneic SBT immunosuppressed with tacrolimus and sirolimus (n = 8); and group D, without immunosuppression (n = 6). Observation period was 30 days. Mucosal biopsies were obtained on days 0, 3, 5, 7, 10, 14, 20, 28 after transplantation. ACR was classified according to standardized grading schema on a scale of indeterminate, mild, moderate, and severe. Serotonin positive cells were quantified as the number of positive cells in 20 high power fields. Results. There were no significant differences in the number of serotonin positive cells and different grades of ACR. In our experiment the number of serotonin positive cells was not a sensitive marker of ACR in the early period after small bowel transplantation.