Presented at:
International Congress of Transplantation, Vienna, Austria, 5-10 September 2004
Mechanisms of Donor-Specific Unresponsiveness in Tolerant Recipients of Combined Non-Myeloablative HLA-Mismatched Bone Marrow and Kidney Transplantation
Shaffer J, Kawai T, Cosimi AB, Fudaba Y, Saidman S, Preffer F, Dombkowski D, Delmonico F, McAfee S, Tolkoff-Rubin N, Ballen K, Dey B, Spitzer TR, Sachs DH, Sykes M
Massachusetts General Hospital, Harvard Medical School, Boston, MA USA
Aims : To evaluate T cell recovery and donor-specific tolerance in vitro following combined non-myeloablative bone marrow and renal transplantation from related haploidentical donors.
Methods : Under an ITN protocol, patients with end-stage renal disease receive combined non-myeloablative bone marrow and renal transplantation with perioperative cyclosporine (CYA). Donor chimerism is measured by peripheral blood microsatellite markers or by flow cytometry using HLA allele-specific mAbs. T cell recovery is followed by flow cytometry. In vitro assays are performed to evaluate donor specific tolerance.
Results : Patient 1 is >18 months post-transplant with normal renal function and no rejection episodes, despite being off all immunosuppression since Day 240. Lymphoid and myeloid chimerism was detectable on Day 7, but undetectable by Day 14. By Day 115, with 110 CD3+ T cells/ul blood, a robust anti-3 rd party MLR response (stimulation index [SI] 106) was seen, with unresponsiveness to donor (SI 1.7). Cultures of Day 187 enriched T cells primed against donor completely suppressed PreTx CTL responses against the donor, but not against 3 rd party. Cultures of Day 187 T cells primed against 3 rd party also completely suppressed PreTx CTL responses against donor, but not against 3 rd party. In contrast, cultures of PreTx cells primed against donor only partially suppressed (by 50%) PreTx CTL responses against donor or 3 rd party. On Days 271 and 367 (T cells >665 cells/ ul), a 3 rd party CML response (PSL 47.5% and 58.2%), but no anti-donor CML response, was detected. Specific hyporesponsiveness to donor persisted in MLR (SI 2 and 50 to donor and 3 rd party, respectively). Removal of Day 367 CD25+ cells revealed an anti-donor MLR response among CD3+CD25- cells (SI 27). Removal of non-T cells revealed a weaker anti-donor MLR (SI 14). An anti-donor CML response (PSL 11%) was revealed only by the removal of CD25+ T cells. Patient 2, who also showed initial mixed chimerism, lost detectable chimerism by Week 2. The patient is >9 months post-transplant with a stable creatinineof 1.8 mg/dl on minimal immunosuppression. At Day 98, with 181 CD3+ T cells/ul, the patient had both CML and MLR responses to 3 rd party (PSL of 64%, SI 22), but was unresponsive to donor. By Day 182, with 84 CD3+ cells/ul, he showed donor-specific unresponsiveness in CML (16% killing of third-party) and global MLR hyporesponsiveness.
Conclusion: Despite donor marrow rejection, two patients with donor kidney graft acceptance (one off all immunosuppression) developed systemic donor-specific unresponsiveness, which may reflect both non-T and T cell-mediated suppressive activity.