INTRODUCTION: Myelodysplastic syndromes (MDS) are classified as oncohematologic, clonal diseases. However, some MDS subtypes lack malignant clinical features. Literary data on the clonality of blood cells in MDS are controversial. Therefore we examined the clonality in the group of our own MDS patients. We were especially interested in the comparison of the clonality of myeloid and lymphoid cell line-ages. METHODS AND MATERIAL: Using X-chromosome inactivation methods based on polymorphism in human androgen receptor gene (HUMARA), iduronate sulphatase gene (IDS) and protein p55 gene, we assessed the clonality of granulocytes, monocytes and T-lymphocytes of 49 female patients with MDS and 12 control women of various ages. RESULTS: Though the results were heterogeneous, certain trends were observed: most frequently monoclonality of monocytes was found (51%), granulocytes were monoclonal in 33% of cases, monoclonal T lymphocytes only in 8% of cases. There was no case with monoclonal T lymphocytes and simultaneously polyclonal myeloid cell fractions. Results differ in relation to the subtypes of MDS. Among controls we observed monoclonality of myeloid cells in one case of an old lady. WE CONCLUDE: The results confirm the presence of malignant clone of myeloid cells in MDS, which can be of variable size. The examination of the clonality in MDS can be significant for the therapy decision. Monoclonal myeloid cells are found least frequently in refractory anemia, most frequently in RAEB-T. Monoclonality of cells in sideroblastic anemia is interesting. The prevailing polyclonality of T lymphocytes in MDS can be explained by the presence of a long-lived cell population originating from the period before the development of MDS. The role of the polyclonal memory T cells in the antitumor immunity in MDS is discussed.

Ustav hematologie a krevní transfuze Univerzity Karlovy