Myelodysplastic syndrome (MDS) is a hematopoietic stem cell disorder affecting individuals over the age of 60 years. It is characterized by ineffective hematopoiesis and extensive apoptosis of hematopoietic cells. MDS patients are at a high risk of transforming in to acute myeloid leukemia. The main cause of apoptosis and escape from immune surveillance in MDS is immune dysregulation caused by a number of factors such as aberrant cytokine production and influence of various immune cells. In the past decade various pro-inflammatory cytokines and a number of immune cells such as Natural Killer cells, regulatory T cells, cytotoxic T cells, mesenchymal stem cells, myeloid derived suppressor cells and dendritic cells have been implicated in immune dysregulation leading to MDS pathogenesis. In this review we focus on the current data available on the role of these immune factors.
Part of the book: Recent Developments in Myelodysplastic Syndromes
Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potential curative treatment for both congenital and hematological malignancies. Immune reconstitution after allogeneic hematopoietic stem cell transplantation is implicated in successful transplant outcomes such as overall survival and relapse-free survival. The reconstitution of immune cell subsets after HSCT occurs in different phases at different time points encompassing pre-engraftment, engraftment, and post-engraftment. The recovery of innate cellular immunity with the appearance of monocytes, dendritic cells, and natural killer cells in peripheral blood correlates with initiation of cellular engraftment. The cellular adaptive immunity is characterized by both thymic-independent expansion of T cells infused with graft and thymus-dependent expansion of naïve T cells derived from donor stem cells. The humoral immunity consists of B-cell reconstitution, which consists primarily of transitional and naïve subsets with the recovery of memory B cells that occur much later. In this review, we highlight the factors affecting immune reconstitution, the reconstitution of innate and adaptive immunity, techniques to assess immune reconstitution, and ways to enhance it.
Part of the book: Cells of the Immune System