Abstract: Objective To study the effect of pretreatment with apoptotic donor spleen cells on spleen lymphocyte function of
recipient rats undergoing islet transplantation to explore new approaches to prolong islet graft survival. Methods Apoptotic
spleen cells from donor rats were obtained by exposure to γ-ray irradiation from60Co. Diabetic SD rat models were randomly
divided into 4 groups to receive tail vein injections with saline (group A), normal cells (group B), apoptotic donor cells (group
C), or necrotic donor cells (group D). One week later, orthotopic transplantation of islets under the renal capsule was
performed. Before and at 1 and 2 weeks after islet transplantation, the recipient rats were examined for proliferative activity of
spleen lymphocytes with CFSE cell staining and for IL-2 and IL-10 expressions in the cells using ELISA. Results Pretreatment
with donor apoptotic cells significantly suppressed the proliferative activity of recipient spleen lymphocytes before and at 1
and 2 weeks after islet transplantation as compared with the other three groups (P<0.05). The level of IL-2 was significantly
decreased while IL-10 increased in apoptotic donor cell pretreatment group compared with those in the other 3 groups at each
time point of observation. Conclusion The effect of pretreatment with apoptotic donor cells on recipient spleen lymphocytes
suggest an important role of apoptotic donor spleen cells in immune tolerance of grafts.