Immunoexpression of 5-methylcytosine (5mc) in Bone Marrow Haematopoietic Cells in Patients with Myelodysplastic Syndromes.

Myelodysplastic syndromes (MDS) are biologically and clinically heterogenous groups of clonal haematopoietic stem cell diseases characterized by ineffective haematopoiesis and peripheral blood cytopenia, with a variable tendency to transform within acute leukaemia (AL). DNA hypermethylation and hypo-methylation are associated with cancer. Thus, the hypermethylation of DNA is essential for the molecular pathophysiology of MDS by inactivating genes involved in cell growth, differentiation and apoptosis. It was documented that the 5-methylcytosine (5mc) immunostaining score of BM haematopoietic mononuclear cells is higher in MDS patients than in a normal control group, and that the prognosis of the disease significantly correlated with global DNA methylation, age and IPSS score. In our study, we analysed the immunocytochemical expression of 5mc in bone marrow (BM) mononuclear cells from 13 MDS patients and a control group consisting of 13 patients with anaemia of chronic disease. The immunopositivity of 5mc BM mononuclear cells was statistically significantly higher in our MDS patients than in patients with anaemia of chronic disease. In most MDS patients (11 out of 13), a higher 5mc immunopositivity of BM mono-nuclear cells (above 10%) was found. Our results are in concordance with data from literature observing that a higher percentage of 5mc immunopositive BM mononuclear cells is documented in MDS patients.