OBJECTIVETo investigate the feasibility of strategy of allograft tolerance induction by injection of FasL-decorated donor splenocytes.

METHODSChimeric FasL with core streptavidin (SA-FasL) was efficiently displayed on the surface of splenocytes by the technology of ProtEx™. Heterotopic heart transplant procedures were performed from donor WF rats to recipient ACI rats, F344 rats were used as third-party. Intraperitoneal injection of ACI rats with "decorated" WF splenocytes was used as the approach to induce tolerance in this study. According to different therapeutic strategies, three groups were set up: SA-FasL group (n = 23), SA group (n = 20) and naive splenocytes only group (n = 8). No treatment group was regarded as control (n = 10). Adoptive transfer was underwent with injection of splenocytes from tolerant recipients into naive ACI followed by heart transplant procedures. Mixed lymphocyte reaction (MLR) and third party transplantation were performed to detect allogenic tolerance.

RESULTSThe injection of ACI rats with WF rat splenocytes displaying SA-FasL on their surface resulted in tolerance to donor, but not F344 third-party cardiac allografts. There were 70% cardiac allografts in SA-FasL group achieved long term survival, and it was significantly higher than the rats in other groups (P < 0.05). Adoptive transfer of splenocytes from long-term graft recipients into naive unmanipulated ACI rats resulted in indefinite survival of secondary WF grafts. Donor specific tolerance was identified by MLR and third-party transplant.

CONCLUSIONThe direct display of SA-FasL on the cell membrane in a rapid and efficient manner provides a practical and clinically applicable means of immunomodulation for tolerance induction with considerable therapeutic potential for transplantation.