Aldehyde dehydrogenase expression drives human regulatory T cell resistance to posttransplantation cyclophosphamide.
High-dose, posttransplantation cyclophosphamide (PTCy) is an effective strategy for preventing graft-versus-host disease (GVHD) after allogeneic blood or marrow transplantation (alloBMT). However, the mechanisms by which PTCy modulates alloimmune responses are not well understood. We studied early T cell reconstitution in patients undergoing alloBMT with PTCy and the effects of mafosfamide, a cyclophosphamide (Cy) analog, on CD4(+) T cells in allogeneic mixed lymphocyte reactions (MLRs) in vitro. Patients exhibited reductions in naïve, potentially alloreactive conventional CD4(+) T cells with relative preservation of memory CD4(+)Foxp3(+) T cells. In particular, CD4(+)CD45RA(-)Foxp3(+hi) effector regulatory T cells (Tregs) recovered rapidly after alloBMT and, unexpectedly, were present at higher levels in patients with GVHD. CD4(+)Foxp3(+) T cells from patients and from allogeneic MLRs expressed relatively high levels of aldehyde dehydrogenase (ALDH), the major in vivo mechanism of Cy resistance. Treatment of MLR cultures with the ALDH inhibitor diethylaminobenzaldehyde reduced the activation and proliferation of CD4(+) T cells and sensitized Tregs to mafosfamide. Finally, removing Tregs from peripheral blood lymphocyte grafts obviated PTCy's GVHD-protective effect in a xenogeneic transplant model. Together, these findings suggest that Treg resistance to Cy through expression of ALDH may contribute to the clinical activity of PTCy in preventing GVHD.
The Sidney Kimmel Comprehensive Cancer Center and Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
Christopher G
CG
Kanakry
Sudipto
S
Ganguly
Marianna
M
Zahurak
Javier
J
Bolaños-Meade
Christopher
C
Thoburn
Brandy
B
Perkins
Ephraim J
EJ
Fuchs
Richard J
RJ
Jones
Allan D
AD
Hess
Leo
L
Luznik
D000328:Adult; D000444:Aldehyde Dehydrogenase / Q000378:metabolism*; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage / Q000494:pharmacology*; D016026:Bone Marrow Transplantation; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007959:Lymphocyte Culture Test, Mixed; D008297:Male; D008875:Middle Aged; D016176:T-Lymphocyte Subsets; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects*
D018906:Antineoplastic Agents, Alkylating; D003520:Cyclophosphamide; D000444:Aldehyde Dehydrogenase