The role of the spleen in pancreas transplantation

Early graft thrombosis and rejection of the graft are the two major causes of graft failure in pancreas transplantation. Inclusion of the spleen in the pancreatic graft has been purported as a possible solution to both complications, but severe graft-versus-host disease led to abolishment of this procedure. By irradiating the donor spleen ex vivo during cold storage, we successfully prevented graft-versus-host disease, allowing us to evaluate the advantages of clinical pancreaticosplenic transplantation. This study reports our experience with 12 pancreaticosplenic transplantations. Using Doppler flow measurements, we have been able to examine the hemodynamic advantages. Our results confirm the purported benefit. Vascular resistance indices in the pancreatic graft are significantly lower when the donor spleen is included. This, however, did not lower the incidence of thrombosis (2 out of 12 cases) in our study. Serial radionuclide studies with 99mTc-hexamethyl propylene amine oxime were performed for further evaluation of graft perfusion. With time the spleen uptake diminishes, compatible with atrophy of the organ. This was confirmed histologically. No indication of an immunologic advantage of transplanting the pancreas together with the spleen was found. All patients went through severe rejection crises. A transient reduction in platelet count (55-88%, mean 71%) of preoperative values was observed. This platelet drop is not seen in patients with a pancreas without spleen transplantation. We conclude that in pancreas transplantation, inclusion of the irradiated spleen has no obvious advantages for early graft thrombosis and rejection of the graft.