Objective: Myeloid-derived suppressor cells (MDSCs) are immature myeloid progenitors, including monocytic and granulocytic subgroups (M-MDSCs and PMN-MDSCs). They exhibit immunoregulatory and immunosuppressive properties by limiting immune-mediated pathology and protecting the host from destructive inflammatory damage. Graft-versus-host disease (GVHD) comprises a series of immune-mediated inflammatory events in which donor-derived T cells target the tissues and organs of the transplant recipient. This study aims to evaluate the behavior of MDSCs during GVHD in patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT).
Materials and Methods: Fifteen patients who underwent allogeneic HSCT were included in the study. MDSCs and their subsets were identified and characterized by flow cytometry on days 0, 30, 60, and 90 post-engraftment.
Results: The median frequency of monocytic MDSCs (M-MDSCs) on the first day of engraftment was significantly higher in patients without GVHD than in those who developed GVHD. Furthermore, the expansion of M-MDSCs occurred significantly earlier than that of the other MDSC subset.
Conclusion: Monocytic MDSCs play a key regulatory role in limiting GVHD and may serve as potential therapeutic targets for GVHD prevention or treatment.