Институт гематологии и трансфузиологии Национальной академии медицинских наук Украины, Киев, Украина Proliferative activity of hematopoietic cells of the bone marrow and peripheral blood and event-free survival of patients with myelodysplastic syndrome – refractory anaemia with excess of blasts-1 (MDS RAEB-1) Пролиферативная активность гемопоэтических клеток костного мозга и периферической крови и бессобытийная выживаемость у пациентов с миелодиспластическим синдромом – рефрактерная анемия с избытком бластов I (МДС РАИБ-І) ______________________ Abstract __________________________________________________________________________ The study indicates the involvement of intranuclear protein Ki-67 in the development of response to treatment in patients with MDS RAEB-1 as one of the pathogenic factors of the disease. <...> Dynamics of Ki-67 expression by haematopoietic cells in PB and BM may serve as a criterion for evaluation of treatment quality and disease prognosis. <...> Восточная Европа», 2016, том 2, № 2 211 Proliferative activity of hematopoietic cells of the bone marrow and peripheral blood and event-free survival of patients with myelodysplastic syndrome – refractory anaemia with excess of blasts-1 (MDS RAEB-1) The myelodysplastic syndrome (MDS) includes a group of diseases of clonal origin, distinctively exhibiting discrepancy between high proliferative activity of haematopoietic cells and ineffective haematopoiesis, dysplasia of bone-marrow haematopoiesis, therapy refractoriness and high risk of transformation into acute leukaemia [1–3]. <...> It is generally known that proliferative activity is a leading factor in the mechanism of malignant transformation of cells and in biological behaviour of the already existing cells. <...> Given that Ki-67 proliferation marker is a well-known factor of the active phase of cell cycle (G1, S, G2, and M-phases) and is absent in G0 phase of cell cycle, analysis of Ki-67 expression is used for prediction of the course of many malignancies, including malignant diseases of the haematopoietic and lymphoid systems [6, 7]. <...> The objective of the study was to measure clinical and haematological parameters, Ki-67 expression dynamics and life expectancy of patients with MDS RAEB-1 prior to its progression into RAEB-2. <...> The white blood cell count in PB in patients of Group I (during the initial period) amounted to 2.9±0.5Ч109 mal rate. <...> The average platelet count was /L, which is by 1.9-fold lower than the rate in healthy subjects (p<0.05). <...> The leucogram of examined patients <...>