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The potential role of γδ T cells after allogeneic HCT for leukemia

Rupert Handgretinger and Karin Schilbach

Abstract

Allogeneic hematopoetic stem cell transplantation (HCT) offers an option for patients with hematologic malignancies, in whom conventional standard therapies failed or are not effective enough to cure the disease. Successful HCT is able to restore functional hematopoiesis and immune function and the new donor-derived immune system can exert a graft-versus-leukemia (GvL) effect. However, allogenic HCT can also be associated with serious risks for transplantation-related morbidities or mortalities like graft versus host disease (GvHD) or life-threatening infectious complications. GvHD is caused by alloreactive T lymphocytes which express the αβ T cell receptor while lymphocytes expressing the γδ T cell receptor are not alloreactive and do not induce GvHD, but can exhibit potent anti-leukemia and anti-infectious activities. Therefore, γδ T cells are becoming of increasing interest in allogeneic HCT and clinical strategies to exploit the full function of these lymphocytes have been and are being developed. Such strategies comprise the in vivo activation of γδ T cells or subsets after HCT by certain drugs or antibodies or the ex vivo-expansion and manipulation of either patient-derived or donor-derived γδ T cells and their subsets and the adoptive transfer of the ex vivo-activated lymphocytes. Based on the absence of dysregulated alloreactivity, such approaches could induce potent GvL effects in the absence of GvHD. The introduction of large scale clinical methods to enrich, isolate, expand and manipulate γδ T cells will facilitate future clinical studies that aim to exploit the full function of these beneficial non-alloreactive lymphocytes.

  • Submitted August 3, 2017.
  • Accepted October 19, 2017.