Effects of donor-derived spleen cells combined with anti CD154 monoclonal antibody on bone marrow transplantation in non-myeloablative conditioning regimen for the induction of allogeneic mixed chimerism

Abstract

Objective To explore the role of donor spleen ceils(Sos)(including transfusion pathway)combined with anti CD154 monoclonal antibody(mAb)on bone marrow transplantation in nonmyeloablative pre-conditioning regimen for induction of aUngeneic mixed chimerism and donor-specific immune tolerance.Methods Lewis rats(Rt11)were used as donors,Wistar-Furth rats(Wistar,Rt1u)as recipients,and Sprague-Oawley(SD)rats as the third party donors.Scs and bone marrow cells(BMCs)were harvested from donor Lewis rats.Recipient Wistar rats were randomly divided into 4 groups,20 rats in each group.In group A,dorsum penis vein(i.v.)injection of Lewis rats 2×108 Scs on day 0 alone.In group B,portal vein(P.V.)injection of Lewis rats 2×108 Scs on day 0 alone.In group C,P.V.injection of Lewis rats 2×108 Scs on day 0,in combination with i.v.injection of Lewis rats 1×108 BMCs on day 3.In group D,P.V.injection of Lewis rats 2×108 Scs on day 0,intraperitoneal injection of 3 μg AH.F5 (hamster anti-rat CD154 mAb)2 h later,in combination with i.v.injection of Lewis rats 1×108 BMCs on day 3.Tolerance was assessed by stimulation index(SI)of one-way mixed lymphocyte reaction(MLR).Rt11 positive chimersim in recipient spleen and thymus was measured by flow cytometric(FACS)analysis on the day 20,40.In rats in group D were additionally subjected to chimerism detection on the day 100.Results SI in group D on the day 20,and 40 was significantly lower than other groups(4.43±0.19,4.97±0.25,P ＜0.01).The results of Rtl1+ assay revealed that there was no chimersim in group A.While chimersim was transient and lower in groups B and C on the day 20,and rapidly decreased.Only group D had stable and higher level chimerism in spleen(32.40±3.29)%,(23.06±3.77)% and thymus(31.08±2.60)%,(24.52±3.22)% on the day 20,and 40.Furthmore,long-term chimerism (＞ 100days)was observed in the group D.Conclusion High level of ehimerism(＞ 30% in peripheral spleen and ＞ 20% in central thymus)provides the foundation to BMCs to play a critical role in the induction or maintenance of tolerance.P.V.injection of Sos and anti CD154 mAb,plus i.v.injection of BMCs had synergistic effect to induce donor-specific tolerance and establish stable allogeneic mixed ehimersim,without participation of megadose BMCs,myleosuppressive drugs and irradiation. Key words: Bone marrow transplantation; Spleen cells; CD154; Chirnerism; Immune tolerance