Presented at:
12th Innovative Therapeutics in Transplantation
Nantes, France, June 15, 2006
Circulating and graft infiltrating regulatory cells in donor stem cell infused kidney transplant patients treated with alemtuzumab
Mathew J, Carreno M, Cirocco R, Rosen A, Vallone T, Garcia-Morales R, Burke GW, Ciancio G, Esquenazi V, Miller J
University of Miami and the VA Medical Center, Miami, FL
Introduction: Recently, we have initiated a clinical protocol in which LRD-kidney transplant patients are treated with Alemtuzumab (Campath-1H; C1H) and infused with donor hematopoietic stem cells (DHSC). In this study we have analyzed the regulatory cells present in the circulation and the allografts of these patients (n=3).
Materials & Methods: Flow cytometry for cell subsets, reverse transcription and real time PCR for Fox-P3 mRNA, and MLR for functional assays were measured.
Results: During the early post-transplant period, the DHSC-C1H recipients were profoundly depleted of peripheral lymphocytes (n=4). As immune cells gradually returned, the CD4+CD25HIGH T-regs were found to be significantly more abundant than in patients treated with Thymoglobulin or Daclizumab, or C1H without DHSC. The CD3+ cells from the DHSC-C1H patients had also higher levels of Fox-P3 expression. Depletion of CD25+ cells significantly increased the post-transplant (at 6 & 12 months) anti-donor MLR responses of these recipients. More importantly, addition of purified post-transplant CD25+ cells as well as post-transplant “chimeric” cells of donor and recipient phenotypes inhibited the anti-donor MLR responses of pre-transplant cryopreserved and thawed recipient PBL in a dose-dependent manner.
Graft infiltrating lymphocytes (from one-year biopsies) grown in a cytokine-rich medium were predominantly of recipient phenotype distributed into CD3+CD4+ T cells and CD16/56+ NK cells with large numbers of CD4+CD25HIGH cells. When tested as modulators, these biopsy cultures also strongly inhibited recipient (pre-transplant) anti-donor MLR responses in a dose-dependent manner.
Conclusions: DHSC-C1H kidney allograft recipients have multiple types of circulating and graft infiltrating regulatory cells which may facilitate allograft acceptance.