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Background. Acquired aplastic anemia (AA) is a non-tumor disease of the blood system and the pathogenesis is based on immune dysregulation directed against own hematopoietic stem cells, which leads to the development of bone marrow aplasia. Some modern research is directed to the study of intrinsic defects of hematopoietic stem cells, and one of which is the change in telomere length. Several large studies have shown the association of telomere shortening in AA patients with decreased overall survival, poor response to immunosuppressive therapy (IST), high rates of relapse and clonal complications.Aim. To study the influence of the initial telomeric DNA regions length in AA patients on the disease course.Materials and methods. 43 adult patients with acquired AA without previous pathogenetic therapy were included in the study. IST was performed according to a standard protocol including the use of hATG and cyclosporine. Flow-FISH was used as the method for measuring relative telomere length, and peripheral blood mononuclear cells were used as the study material.Results. Telomere length determined before IST did not differ between non-severe and severe AA, but there were significant differences depending on disease duration (p = 0.032). Initially short telomeres correlated with a lower rate of achieving hematologic improvement (53 % vs. 80 %; p = 0.059). In addition, significantly worse results were obtained in achieving partial and complete remission in patients with initially short telomeres compared to those with initially long telomeres (37 % vs. 62 % and 5 % vs. 23 %, respectively; p

Background. Aplastic anemia (AA) is a non-tumor and rare disease of the blood system, characterized by deep pancytopenia due to the development of bone marrow aplasia with immune-mediated damage of hematopoietic stem cells. Research results indicate the presence of antigenic effects leading to pathological activation and dysregulation of the T cells in the bone marrow with increased production of pro-inflammatory cytokines that damage hematopoietic stem cells. The triggering factor that initiates the cascade of immune reactions is currently unknown. The high efficiency of immunosuppressive therapy (IST), which allows achieving remission in the majority of AA patients, is evidence of the immune genesis of the disease. The pathogenesis of AA is currently being actively studied. The participation of T cell subpopulations in immune response is beyond doubt, but the issues of their significance in the AA pathogenesis have not been fully studied. A more detailed understanding of the AA development mechanisms is necessary for the development of long-term effective treatment.Aim. To investigate the T cells subpopulation in bone marrow of AA patients during IST.Materials and methods. The study included 41 patients over 18 years of age with newly diagnosed acquired AA without previous IST. Treatment was carried out according to a protocol including horse antithymocyte globulin and cyclosporine. Flow cytometry was used to detect T cell subpopulations. Bone marrow examination was performed at three time points: initially, 3 and 6 months after initiation of combined IST.Results. Multidirectional changes in the T cell subpopulations ratio before the start of IST were found in all AA patients included in the prospective study: most patients had a higher proportion of effector CD4+ and CD8+ T cells (61 and 83 % of patients, respectively), memory CD4+ T cells (63 % of patients), and a lower proportion of naive CD4+ and CD8+ T cells (81 and 51 % of patients, respectively) compared to donors (p

Background. Differentiation syndrome (DS) is a potentially fatal complication of therapy for acute promyelocytic leukemia (APL) with an incidence of up to 48 %. To date, no reliable DS risk factors have been found, with the exception of leukocytosis at the APL onset.Aim. To determine the risk factors associated with DS in patients with APL during induction therapy with arsenic trioxide (ATO) and tretinoin (ATRA).Materials and methods. The study included 39 patients with APL, 29 (74.4 %) of them were classified as low-risk according to ELN (European Leukemia Net), 10 (25.6 %) were classified as high-risk. At the disease onset, cytological and molecular (chimeric transcript PML::RARα, FLT3-ITD mutation) bone marrow studies were performed, the expression of 28 differentiation antigens by blood and bone marrow blast cells was determined (markers of early precursors, myeloid and lymphoid differentiation, cell adhesion molecules, chemokine receptors, integrins, selectin), body mass index (BMI) and the leukocytes number dynamics during induction course were assessed. All patients received ATRA and ATO therapy. Patients from the high-risk group at the onset received 1–3 injections of idarubicin (12 mg/m2) and dexamethasone (8–10 mg/m2 2 times a day) to prevent DS until leukocytosis reduced. In cases of DS, dexamethasone was prescribed at a dose of 10 mg/m2 2 times a day; in cases of severe DS, the induction course was interrupted.Results. Of the 39 patients, 12 (30.8 %) were diagnosed with DS: 20 % of high-risk patients (2/10) and 34.5 % of low-risk patients (10/29). There was no statistically significant association of leukocytosis more than 10 × 109 /L at onset, microgranular morphology of blast cells, bcr3-variant PML::RARα, FLT3-ITD mutation with DS. In multivariate analysis, the probability of DS was associated with BMI ≥30 kg/m2 and mean fluorescence intensity of CD38 antigen by blast cells, regardless of risk group. based on the results of the ROC-analysis, the threshold value of mean CD38 fluorescence intensity was set at 25,000 cu, if exceeded, DS is highly likely to develop.Conclusion. the high incidence of DS among low-risk patients is probably due to the lack of prophylactic glucocorticosteroids administration for the development of leukocytosis during ATRA and ATO therapy. BMI ≥30 kg/m2 and mean CD38 fluorescence intensity more than 25,000 cu were identified as statistically significant DS risk factors.

Background. Aplastic anemia proceeds with bone marrow failure and is associated with immunological suppression of normal blood stem cells’ proliferation, which lead to bone marrow aplasia. autoimmune aggression and internal defects of blood stem cell that cause abnormal hematopoiesis are being actively studied. An important role in the pathogenesis of the aplastic anemia is played by instability of telomere length (TL). determination of the initial TL makes it possible to clearly differentiate between the aplastic anemia and dyskeratosis congenita. also, it helps to identify the group of patients with short telomeres for prediction of therapy response. Aim. To investigation the TL of various blood and bone marrow cells in patients with aplastic anemia before treatment. Materials and methods. The group of patients with aplastic anemia was investigated (n = 45). blood donors (n = 32) and bone marrow donors (n = 10) of different ages were included in the reference group. adult patients with dyskeratosis congenita (n = 5) were included in the comparison group. Relative and absolute tl was identified in peripheral blood and bone marrow mononuclear cells, monocytes, lymphocytes by flow-FISH technique (combination of flow cytometry and fluorescence in situ hybridization). Results. Relative and absolute TL was comparable in different blood and bone marrow cells in patients with aplastic anemia before treatment. TL in peripheral blood and bone marrow mononuclear cells wasn’t significantly differed in groups of patients with aplastic anemia and healthy donors. Telomeres in patients with dyskeratosis congenita were identified as “ultrashort” and were significantly shorter than in patients with aplastic anemia. Conclusion. Determination of TL in patients with aplastic anemia is modern examination method, which is a necessary step of differential diagnosis between aplastic anemia and dyskeratosis congenita, which is the disease from group of constitutional bone marrow aplasia. It is preferred to identify the TL in adult patients with aplastic anemia by the flow-FISH. It is necessary to investigate the TL to predict treatment response and to identify risks of developing adverse experiences, which include relapse and clonal evolution.

Background. The effectiveness of therapy for acute T-lymphoblastic leukemia (T-ALL) and T-lymphoblastic lymphoma (T-LBL) has significantly improved over the past decades, including through the implementation of hematopoietic stem cell transplantation (HSCT). The Russian multicenter ALL-2009 study (ClinicalTrials.gov NCT01193933) showed that performing autologous HSCT (auto-HSCT) in patients with T-ALL/LBL improves long-term results. However, the study was non-randomized and the need for auto-HSCT in clinical practice requires careful study.Aim. To assess the significance of auto-HSCT in patients with T-ALL/LBL in the framework of ALL-2016 multicenter, prospective, randomized study (ClinicalTrials.gov NCT03462095).Materials and methods. The study included 109 adult patients with T-ALL/LBL (m:f 82:27). Median age was 31 (18– 52) years. T-ALL was diagnosed in 88 (81 %) patients, T-LBL in 21 (19 %) patients. All patients are treated according to the ALL-2016 protocol. Using the web platform, upon completion of induction therapy (+70 days), all T-ALL/LBL patients who achieved clinical and hematological remission were randomized to the auto-HSCT arm or chemotherapy alone (CT). Centralized monitoring of minimal residual disease (MRD) in bone marrow samples was performed by multicolor flow cytometry at the control points according to the ALL-2016 protocol. Statistical analysis was performed using SAS 9.4.Results. 87 patients with T-ALL/LBL were randomized: 44 to the auto-HSCT arm and 43 to the CT arm. Further analysis included 25 patients who underwent auto-HSCT and 36 patients receiving only CT. Three-year relapse-free survival in T-ALL is estimated at 62 % (auto-HSCT) vs. 81 % (CT) (p = 0.3422), and in T-LBL – 67 % (auto-HSCT) vs. 79 % (CT) (p = 0.59). MRD persistence on the +70th day of therapy according to the ALL-2016 protocol was determined in 40 % of patients (autoHSCT) and in 67 % (CT) (p = 0.057). In a multivariate analysis, it was determined that T-ALL from early T-cell precursor (ETP-variant) and MRD persistence after the end of II phase induction are the main risk factors for relapse in the treatment according to the ALL-2016 protocol.Conclusion. Performing auto-HSCT both in patients with T-ALL and T-LBL, and with MRD persistence on day +70 according to the ALL-2016 protocol did not improve long-term results. The development of new programs for the treatment of patients with MRD persistence, as well as the ETP variant of T-ALL, is of current interest.

The graft-versus-host disease (GVHD) is among the most common complications after hematopoietic stem cell transplantation (allo-HSCT). The main tools for GVHD prevention remain calcineurin inhibitors (cyclosporin A, tacrolimus), methotrexate, mycophenolate mofetil. Upon implementation of reduced-intensity conditioning regimens, antithymocyte globulin was widely introduced. However, negative effects upon reconstitution of T-cell immunity have been noted, thus increasing risk of severe infectious complications and disease relapse. With extended practice of HSCT from alternative (partially matched or haploidentical) donors, cyclophosphamide was increasingly used. Our aim was to study reconstitution of immune cell subpopulations in the patients undergoing bone marrow transplantation (BMT), when using different GVHD prophylaxis regimens, including the schedules with post-transplant CP usage. The study concerned 44 cases classified into 2 groups. The first one included patients with standard immunosuppressive therapy, antithymocyte therapy, cyclosporine A, methotrexate, mycophenolate mofetil. The second group included the patients who received CP as immunosuppressive drug combined with other treatments (cyclosporine A, methotrexate, mycophenolate mofetil). At specified control terms, (D+14, +30, +60, +90) the blood leukocyte subpopulations were assayed by means of multicolor flow cytometry. Absolute counts of CD4+ cells in HSCT recipients treated with CP post-BMT proved to be sufficiently lower at D+14 and +30, than in those treated with classical immunosuppressive therapy. However, at later terms, (D+60, +90), these differences were not observed. Moreover, in CP-treated bone marrow recipients, absolute numbers of CD8+ cells was significantly higher, compared to the patients who received conventional GVHD prophylaxis. Reconstitution of the studied lymphocyte populations in hematopoietic cell recipients did not depend on the GVHD prophylaxis regimen. Usage of CP combined with bone marrow as a source of stem cells, brings about sufficient decrease of some cell populations (CD4+; CD8+; NK cells) at early terms post-transplant. Administration of CP combined with hematopoietic stem cells as the source of hematopoietic graft seems to be more reasonable.

Aim.Analysis of the effectiveness of the MSCs aministration as the second- or third-line therapy of acute GVHD (aGVHD) resistant to glucocorticosteroid treatment. Materials and methods.The study included 35 patients who received MSCs obtained from the bone marrow of healthy donors as a treatment of steroid-resistant aGVHD. The clinical parameters of patients, MSCs cultural characteristics, the MSC expression profile for various genes including those involved in immunomodulation, expression of cells surface markers, the source of MSCs, as well as the frequency and number of MSC administrations were analyzed. Results.Response to therapy was achieved in 74% of cases, a complete response was reached in 13 (37%) patients, partial response/clinical improvement was demonstrated in 13 (37%). This treatment was ineffective in 9 patients. The prediction of a group of patients with good response to MSC therapy turned to be impossible. The differences between the effective and ineffective for the GVHD treatment MSCs samples were found. The effective ones were characterized with a decreased total MSCs production and an increase in the main histocompatibility complex and PDL-1 antigens expression. Conclusion.These data allow to select optimal samples for aGVHD treatment that can improve clinical results. aGVHD treatment with MSCs has shown efficacy comparable to other treatment approaches. Given the low percentage of complications and the absence of significant adverse effects, MSC therapy seems to be one of the optimal approaches to the treatment of resistant forms of GVHD.

Issue.The study of activating mutations (NRAS,KRAS,FLT3,JAK2,CRLF2genes) of RAS/RAF/MEK/ERK and JAK/STAT signaling pathways in B-cell acute lymphoblastic leukemia (B-ALL) in adult patients which are included in Russian multicenter clinical trials. Materials and methods.Within the multicenter study there were 119 adult patients included withde novoB-ALL. The study was considered as prospective and retrospective. The group withBCR-ABL1-negative B-ALL consisted of up to 93 patients (45 male and 48 female, at the age of 17 to 59, the median age 31), they were treated according to the protocols ALL-2009, ALL-2016. The median follow-up lasted for 19 months (1119). The group withBCR-ABL1-positive B-ALL with up to 26 patients (10 male and 16 female, at the age of 23 to 78, the median age 34 years) was included in the study as well. The treatment was carried out according to the protocols ALL-2009 and ALL-2012 in combination with tyrosine kinase inhibitors. The median follow-up lasted for 23 months (4120). The molecular analysis of activating mutations inNRAS,KRASgenes (RAS/RAF/MEK/ERK signaling pathway) andJAK2,CRLF2genes (JAK/STAT signaling cascade) was performed via Sanger sequencing. The internal tandem duplications (ITDs) inFLT3gene were studied by fragment analysis. The evaluation of CRLF2 expression was fulfilled via flow cytometry. Results.Activating mutations inNRAS,KRAS,FLT3genes were found in 22 (23.6%) patients withBCR-ABL1-negative B-ALL. In total, 23 mutations were revealed in theNRAS(n=9),KRAS(n=12), andFLT3(n=2) genes, according to statistics that was significantly more frequent than withBCR-ABL1-positive B-ALL, these genes mutations were not identified in patients (p=0.007). The frequency of mutations detection inKRASandNRASgenes in patients withBCR-ABL1-negative B-ALL was comparable as 12.9% (12 of 93) to 9.7% (9 of 93), respectively (p=0.488). One patient was simultaneously revealed 2 mutations in theKRASgene (in codons 13 and 61).FLT3-ITD mutations were detected in 3.5% (2 of 57) cases ofBCR-ABL1-negative B-ALL. In patients withBCR-ABL1-positive B-ALLFLT3-ITD mutations were not assessed. Violations in the JAK/STAT signaling cascade were detected in 4 (4.3%) patients withBCR-ABL1-negative B-ALL. They were represented by the missense mutations ofJAK2gene (n=3) and the overexpression of CRLF2 (n=2); in one patient were detected the overexpression of CRLF2 and a mutation inJAK2gene simultaneously. No mutations were found inCRLF2gene. In patients withBCR-ABL1-positive B-ALL noJAK2mutations were detected. As long as analyzing demographic and clinical laboratory parameters between groups of patients with and without mutations, there were no statistically significant differences obtained. In the analyzed groups of patients, long-term therapy results did not differentiate according to the mutations presence inNRAS,KRAS,FLT3,JAK2genes. Also, substantive differences were not shown in the rate of the negative status achievement of the minimum residual disease between patients with and without activating mutations in the control points of the protocol (on the 70th, 133rd and 190th days). Conclusion.NRAS,KRAS,FLT3,JAK2activating mutations do not affect the long-term results of the therapy and the rate of the negative status achievement of the minimum residual disease in patients withBCR-ABL1-negative B-ALL treated by the Russian multicenter clinical trials.

Background. In addition to anti-HLA-I and anti-HPA-antibodies and specific cytotoxic T-lymphocytes, another cause of immune refractoriness to donor's platelet transfusions could be a platelet-associated different classes immunoglobulins PAIg (G, M, A) and C3 / C4‑components of complement system (PAC3, PAC4). These markers can be detected by flow cytofluorometry of double-stained platelets. The fixation density of immunoglobulins and components of complement systems were measured by the mean fluorescence intensity (MFI).Objective: to study additional factors that aggravate the course of refractoriness to donor's platelet transfusions in patients with aplastic anemia (AA) and hemoblastosis.Materials and methods. 77 patients (AA – 47, myelodysplastic syndrome (MDS) – 10, acute myeloid leukemia (AML) – 20) admitted to National Research Centre for Hematology during 11.09.2016–04.28.2018 were enrolled in the study. M / f ratio was 33 / 44, median age was 36 yrs. (19–71 yrs.). Plasmapheresis and cross-matching for PRP selection were used for patients with refractoriness to donor's platelet transfusion. PAIg (G, M, A) and PAC3 / C4 detection and density (MFI) were evaluated in all patients by flow cytofluorometry of doublestained platelets (CD41a-PE; IgA, M, G-FITC; C3 / C4‑FITC) and MFI measurement. Patients with AA were investigated on different stages of therapy and if refractoriness to donor's platelet transfusion is developed. Blood donors (n = 28) MFI measurement results were established as negative control.Results. It was found that MFI PAIgG/M/А and PAC3/С4 was higher in all groups of the patients (АА, MDS, AML), as compared with donors. MFI of PAIgM and PAIgA in patients were significant higher than MFI of PAIgG and PAC3 / C4. Combination of PAIgM / A, PAIgM / C3 / C4 and PAIgA / C3 / C4 were more frequent. Multiple transfusions of PRP were associated with PAIgA and PAC3 detection. Development of refractoriness to donor's platelet transfusions was accompanied by alloantibodies (HLA-I, HPA) and PAIgM, PAC4 detection. In patients of AA group during development of refractoriness to donor's platelet transfusions and multiple infection complications the high density of PAIgM and PAIgA were identified. Relapse of AA was accompanied MFI of PAC3 density increment.Conclusion. In addition to application of a certain transfusion therapy algorithm it is also necessary to detect PAIg (G, M, A) and PAC3 / C4 for prediction of severe refractoriness to donor's platelet transfusions.

Background . Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal diseases of the hematopoiesis system characterized by dismyelopoiesis and cytopenia, the presence of cytogenetic aberrations and a high risk of transformation into acute myeloid leukemias. Diagnosis of MDS requires a comprehensive approach and mandatory performance of cytological, cytochemical and cytogenetic studies of bone marrow aspirate, as well as histological examination of trephine biopsy. However, in some cases it is necessary to undergo a diagnostic test that would allow verification of the MDS. The study of bone marrow aspirate by multicolor flow cytometry (MFC) can be considered as an additional diagnostic criterion in the diagnosis of MDS.The objective of the study was to estimate the incidence of myelodysplastic features in patients with various forms of MDS by the MFC method. Materials and methods . The study included 79 patients with MDS: 8 with MDS with 5q deletion, 33 with MDS without excess blast cells and 38 with excess of blasts. A bone marrow aspirate test was performed by 6-color flow cytometry. The control group included 35 donors of allogeneic bone marrow. The analysis resulted in a conclusion on the Ogata score scale, the Wells prognostic scale and the combined Ogata–Wells scale. When using the screening method, the presence of two or more cytometric signs of MDS was detected in 60 (75.9 %) of 79 MDS patients. Wells score was higher in MDS group with an excess of blast than in others. Using the combined Ogata–Wells scale, cytometric aberrations were found in 70 (88.6 %) of 79 MDS patients. In patients with MDS with an excess of blasts, the incidence of increased CD34+ and/or CD117+ myeloid cells was higher than in MDS patients without an excess of blasts and an MDS with a 5q deletion. The frequency of abnormal cytometric parameters (anomalous expression of CD34, CD117, CD56+ myeloblasts) in these groups did not differ. In patients with isolated 5q deletion and MDS without excess of blasts, an increased proportion of CD7+CD34+ cells was more often detected than in MDS with an excess of blasts.Conclusion . Thus, cytometric abnormalities in MDS are common, even in patients without excess of blasts. The MFC method can be used as an additional diagnostic method in the initial diagnosis of MDS.

Background. Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease that manifests by the accumulation of tumor monoclonal B-lymphocytes in the bone marrow, peripheral blood and secondary lymphoid organs. Recently it was found that CLL cells are able to form immunological synapses with microenvironment cells, directly and indirectly affecting their function. Therefore, it became clear that the pathogenesis of CLL is not only escape of apoptosis but also the ability of CLL cells to cause T-lymphocyte anergy, thereby avoiding immune surveillance.Objective: to study the expression of FAS, co-stimulatory molecules CD80 and CD86, PD-1, PD-L1 on CLL cells, and also to study the basic subpopulations of T-cells (naїve, memory, effector cells).Materials and methods. The study included 46 CLL patients: 16 patients with disease progression after chemotherapy and 30 patients with newly diagnosed CLL. “Primary” patients are categorized according to J. Binet’s CLL stages. Stage A was established in 14 patients, B – 10, C – 6. The control group included 29 healthy donors. Peripheral blood was used as a material for analysis. The study was performed on a 6-color flow cytometer BD FACS Canto II (BD Biosciences, USA).Results. In CLL patients, the proportion of CD80+, CD86+, FAS+ B-cells was significantly lower than in donors. In “primary” patients the proportion of CD80 + CLL cells was higher than in patients with CLL progression. Among “primary” patients the proportion of CD80+ and CD86+ was lower in advanced stages of the disease. In patients with CLL progression the proportion of FAS+ B cells was higher than in “primary” patients. The proportion of PD-1+ B cells in CLL patients was higher than in donors and “primary” patients. The proportion of PD-1+ tumor cells was significantly lower in advanced stages of the disease. The proportion of PD-L1+ B cells in CLL patients was lower than in donors. Among the “primary” patients, the proportion of PD-L1+ B-lymphocytes was higher in stage A. The proportion of PD-1+ Thelpers was higher in CLL patients than in donors, and among “primary” patients it was higher in advanced stages of the disease. The proportion of PDL1+ T-helpers and cytotoxic T-cells in CLL patients was lower than in donors. The proportion of naїve cells (CD95-CD28+) in patients compared with donors was lower and the proportion of effector cells (CD95+ CD28–), memory cells (CD95 + CD28 +) was higher, a proportion of CD8+ memory T-cells was higher among patients in the advanced stage of CLL.Conclusion. Therefore, a decline the CD80/CD86+ B-cells in CLL can cause ineffectiveness of an immunological synapse between tumor cells and T-cells, which leads to anergy of T-lymphocytes. Decline expression of the FAS receptor allows tumor CLL cells to avoid FAS-mediated apoptosis. A change in the T-cell pool toward memory cells and effectors, the acquisition of a CD4+PD-1+ (“exhausted”) phenotype impaired antitumor immunity and possible leads to disease progression.

The frequency of achieving complete remission, as well as overall and disease-free survival, in multiple myeloma (MM) had increased due to introduction in MM treatment regimens of high-dose chemotherapy with following autologous hematopoietic stem cell transplantation (ASCT). However the number of relapses remains high, caused by persistence of residual tumor cells, i.e., the presence of minimal residual disease (MRD). One of the methods for MRD study is multicolor flow cytometry (MFC) where abnormal expression of surface antigens on myeloma plasma cells (PC) is determined. The aim of our study was to investigate the MRD by MFC before and after ASCT, the frequency of MRD-negative status achievement in complete remission (CR) patients at +100 days after ASCT and the frequency of abnormal expressed antigens on myeloma plasma cells. The study included40 MMpatients in CR at +100 days after ASCT and showed that the most common aberrations of PC were: abnormal absence of CD19 and/or CD27, decreased expression of CD38 and abnormal presence of CD56. The proportion of myeloma PCs from all bone marrow cells decreased significantly after ASCT: 20 % of patients acquired MRD-negative status, 10 % had a decrease in the number of abnormal PCs by one fold. Analysis of probability of immunochemical relapse showed that the worst prognosis was in patients with MRD-positive status before and after ASCT. During the MRD monitoring within 3-18 months, MRD-relapses were detected with the subsequent development of immunochemical relapse. The detection MRD in the dynamics is more informative than the study at only one step of therapy. It may help to select more adequate treatment for patient with multiple myeloma in each specific case.

Over the past 20 years, approaches to the therapy of multiple myeloma have undergone significant changes, and frequency of achieving remission of the disease increased. The new diagnostic methods allowed evaluating the more deep therapy response and predicting the relapse: allele-specific polymerase chain reaction, next generation sequencing, multicolor flow cytometry may detect a minimal residual disease (MRD) with a sensitivity of 10–5 to 10–6. Evaluation of MRD by flow cytometry is a dynamically developing direction of research. The aim of multicenter investigations using flow cytometry for MRD-searching in multiple myeloma is standardization, increasing the sensitivity and specificity of this method. The article presents data on the methods used in monitoring MRD, as well as advances in flow cytometry.

We have studied the morphology and immunophenotype of circulating tumor cells isolated from peripheral blood of 22 patients with splenic marginal zone lymphoma and show that both of them are highly heterogeneous. Using a cell-binding microarray we have demonstrated that the circulating lymphoma cells are positive for CD19 (100 %), CD20 (100 %), CD22 (100 %), surface IgM (73 %), CD38 (23 %), CD5 (9 %), CD11c (36 %), CD103 (5 %), CD25 (32 %), CD23 (23 %) and these immunophenotypes are confirmed in all cases by flow cytometry.Higher surface density of lymphocyte binding onto anti-CD antibody microarray spots compared to blood smears permits to find circulating lymphoma cells even in leukopenic patients.

Here we describe and qualitatively characterize the distribution of mononuclear cells isolated from bone marrow aspirate of healthy donors and sorted by their surface CD antigens on a cell microarray by morphology (for 11 donors) and by absence or presence of α-naphthyl butyrate esterase and naphthol AS-D chloroacetate esterase (for 9 donors). These data can be used as a reference for the diagnosis of acute myeloid leukemia using the cell microarray.

We describe an application of a cell-binding microarray – to parallel study of morphology, tartrate-resistant acid phosphatase activity and detection of surface markers on peripheral blood lymphocytes of 90 atients with suspected hairy cell leukemia (HCL). We have formulated the microarray-based diagnostic criteria for hairy cell leukemia, hairy cell leukemia variant (HCLv) and splenic marginal zone lymphoma (SMZL). According to these criteria we have suggested the presence of HCL for 55 patients, HCLv – for 7 patients and SMZL – for 10 patients from the studied cohort. These diagnoses were confirmed by standard diagnostic methods in all cases. These results show that the cellbinding microarray can be used in differential diagnosis of HCL, while the high sensitivity of the microarray permits to detect the leukemic cells in spite of leukopenia and low hairy cell content.

Aim. To determine the efficiency of maintenance therapy with bortezomib in patients with multiple myeloma (MM) who have achieved complete remission (CR) after autologous hematopoietic stem cell (auto-HSCT), depending on the presence of minimal residual disease (MRD). Subjects and methods. In January 2014 to February 2016, fifty-two MM patients (19 men and 33 women) aged 24 to 66 years (median 54 years), who had achieved CR after auto-HSCT, were randomized to perform maintenance therapy with bortezomib during a year. On day 100 after auto-HSCT, all the patients underwent immunophenotyping of bone marrow plasma cells by 6-color flow cytometry to detect MRD. Relapse-free survival (RFS) was chosen as a criterion for evaluating the efficiency of maintenance therapy. Results. After auto-HSCT, MRD-negative patients had a statistically significantly higher 2-year RFS rate than MRD-positive patients: 52.9% (95% confidence interval (CI), 35.5 to 70.5%) versus 37.2% (95% CI, 25.4 to 49.3%) (p=0.05). The presence of MRD statistically significantly increased the risk of relapse (odds ratio 1.7; 95% CI, 1.2 to 3.4; p=0.05). Two-year cumulative risk of relapse (using the Kaplan-Meier) after auto-HSCT did not statistically significantly differ in MRD-negative patients receiving (n=15) and not receiving (n=10) maintenance therapy with bortezomib (p=0.58). After completion of maintenance treatment, 42% of the MRD-positive patients achieved a negative status. In the MRD-positive patients who had received maintenance therapy, the average time to recurrence was 5 months longer than that in the naïve patients: 17.3 versus 12.3 months. Conclusion. The MRD status determined in MM patients who have achieved CR after auto-HSCT is an important factor for deciding on the use of maintenance therapy.

Aim. To identify a parameter predicting a collection of at least 2·106 CD34+ hematopoietic stem cells (HSC)/kg body weight per leukapheresis (LA) procedure. Subjects and methods. The investigation included 189 patients with hematological malignancies and 3 HSC donors, who underwent mobilization of stem cells with their subsequent collection by LA. Absolute numbers of peripheral blood leukocytes and CD34+ cells before a LA procedure, as well as a number of CD34+ cells/kg body weight (BW) in the LA product stored on the same day were determined in each patient (donor). Results. There was no correlation between the number of leukocytes and that of stored CD34+ cells/kg BW. There was a close correlation between the count of peripheral blood CD34+ cells prior to LA and that of collected CD34+ cells calculated with reference to kg BW. Conclusion. The optimal absolute blood CD34+ cell count was estimated to 20 per µl, at which a LA procedure makes it possible to collect 2·106 or more CD34+ cells/kg BW.