Reduced regulatory T cells (Treg) in bone marrow preferentially associate with the expansion of cytotoxic T lymphocytes in low risk MDS patients.

The myelodysplastic syndromes (MDS) include clonal bone marrow (BM) disorders characterised by the emergence/dominance of dysplastic progenitors in the context of ineffective haematopoiesis, peripheral cytopenias and increased risk of acute myeloid leukaemia (AML). The link between immune dysregulation and MDS has been suggested . Autoimmune attack to normal precursors as well as the activity of bystander T cells, recruited during an immune‐response against dysplastic antigens, were hypothesised as relevant for the selection of dysplastic clones that are able to escape immune‐mediated damage. The involvement of Natural Killer cells was also described.