Graft rejection has been defined as the mirror image of graft-versus-host disease, which is biologically characterized primarily as a Th1-type process. As such, we reasoned that graft rejection would represent a Th1 response amenable to Th2 modulation. Indeed, adoptive transfer of host Th1-type cells mediated rejection of fully MHC-disparate murine bone marrow allografts more effectively than host Th2-type cells. Furthermore, STAT1-deficient host T cells did not differentiate into Th1-type cells in vivo and failed to mediate rejection. We next hypothesized that donor Th2 cell allograft augmentation would prevent rejection by modulation of the host Th1/Th2 balance. In the setting of donor Th2 cell therapy, host- anti-donor allospecific T cells acquired Th2 polarity, persisted posttransplantation, and did not mediate rejection. Abrogation of rejection required donor Th2 cell IL-4 secretion and host T-cell STAT6 signaling. In conclusion, T cell-mediated marrow graft rejection primarily resembles a Th1-type process that can be abrogated by donor Th2 cell therapy that promotes engraftment through a novel mechanism whereby cytokine polarization is transferred to host T cells. © 2008 by The American Society of Hematology.
Mariotti, J., Foley, J., Ryan, K., Buxhoeveden, N., Kapoor, V., Amarnath, S., & Fowler, D. H. (2008). Graft rejection as a Th1-type process amenable to regulation by donor Th2-type cells through an interleukin-4/STAT6 pathway. Blood, 112(12), 4765–4775. https://doi.org/10.1182/blood-2008-05-154278