The role of regulatory T cells during the attenuation of graft-versus-leukemia activity following donor leukocyte infusion in mice

We investigated how the graft-versus-leukemia (GVL) effect is attenuated in the tumor microenvironment using a murine model of non-myeloablative allo-HSCT (NM-HSCT) plus delayed donor leukocyte infusion (DLI) in a haploidentical B6 → F1 strain combination. In-line with aggravated leukemia growth, the proportions of effector T cells expressing IFN-γ (Teffs) in spleen were reduced and attenuated GVL activity was found to be accompanied by a rebound in CD4+Foxp3+ regulatory T cells (Tregs) in tumor-draining lymph nodes and tumor tissues. DLI-derived Tregs and Teffs may be potential indicators of presence of leukemic progression after DLI in this GVL model.

► We investigated how the graft-versus-leukemia (GVL) activity induced by donor leukocyte infusion (DLI) after a haploidentical B6 → F1 non-myeloablative allogeneic hematopoietic stem cell transplantation is attenuated at the tumor microenvironment.
► Aggravation of tumor growth was in line with a rebound in CD4+Foxp3+ regulatory T cells (Tregs) and a reduction in IFN-γ-producing effector T cells (Teffs).
► DLI-derived Tregs and Teffs may be potential indicators for maintenance of GVL activity after DLI in this GVL model.