Next generation sequencing is used to determine full-length sequences of HLA genes at the 4-field (allelic) resolution. The study was aimed at determining frequency and diversity of HLA alleles in a cohort of blood donors from the Registry of the National Research Center for Hematology who design ated themselves as Russians (including some not routinely typed variations in HLA gene regions). The studied population consisted of 1510 donors. HLA typing was performed by next generation sequencing. Libraries were performed with AllType NGS Amplification Kits (One Lambda, USA) and sequenced using MiSeq (Illumina, USA). Data analysis used the TypeStream Visual Software V2.0.0.68 (One Lambda, USA) and IPD-IMGT/HLA database 3.40.0.1. Arlequin 3.5 software was used for estimation of allele and haplotype frequencies, deviation from Hardy-Weinberg equilibrium. 82 HLA-A, 156 HLA-В and 85 HLA-С alleles were identified with four-field resolution. 45 HLA-DRB1 and 18 HLA-DQB1 alleles were identified with 2-3-field resolution. Considerable HLA diversity was found among the donors self-designated as Russians: the population had large numbers of distinct alleles at each HLA gene, high percentage of alleles (25-32% of HLA class I) were revealed only once. Sufficient numbers of new alleles were registered which are absent in the IPD-IMGT/HLA database. Considerable allelic diversity in Russian population is due to low-incidence alleles. Despite this diversity, the majority of HLA alleles detected at each locus were common. Significant HLA diversity of the donors was connected with a large number of alleles with rare occurrence. The novel alleles identified in our study differed from the known alleles by single nucleotide substitutions. The most common alleles at the four-field level were as follows: A*02:01:01:01 (27.1%), C*07:02:01:03 (13.1%), A*03:01:01:01 (13.0%), B*07:02:01:01 (13.0%), A*01:01:01:01 (11.6%) and C*07:01:01:01/16 (10.4%). The HLA alleles, which are common for Russian populations, are not always common or well-documented alleles in present catalogues. The data obtained in this study may be used as a reference sample for estimation of HLA allele frequencies in Russian population, for proper frequency evaluation of specific alleles when searching donors for allogeneic hematopoietic stem cell transplantation, as well as for association studies between HLA alleles and different diseases, and for research in population genetics.

Background: Myelodysplastic syndromes (MDS) can present a challenge for clinicians. Multicolor flow cytometry (MFC) can aid in establishing a diagnosis. The aim of this study was to determine the optimal MFC approach for MDS. Methods:The study included 102 MDS (39 low-grade MDS), 83 cytopenic patients without myeloid neoplastic disorders (control group), and 35 healthy donors. Bone marrow was analyzed using a six-color MFC. Analysis was conducted according to the "Ogata score," "Wells score," and the integrated flow cytometry (iFC) score. Results:The respective sensitivity and specificity values were 77.5% and 90.4% for the Ogata score, 79.4% and 81.9% for the Wells score, and 87.3% and 87.6% for the iFC score. Specificity was not 100% due to deviations of MFC parameters in the control group. Patients with paroxysmal nocturnal hemoglobinuria (PNH) had higher levels of CD34 + CD7 + myeloid cells than donors. Aplastic anemia and PNH were characterized by a high proportion of CD56 + cells among CD34 + precursors and neutrophils. The proportion of MDS-related features increased with the progression of MDS. The highest number of CD34 + blasts was found in MDS with excess blasts.MDS with isolated del(5q) was characterized by a high proportion of CD34 + CD7 + cells and low granularity of neutrophils. In 39 low-grade MDS, the sensitivities were 53.8%, 61.5%, and 71.8% for Ogata score, Wells score, and iFC, respectively. Conclusion:The results support iFC as a useful diagnostic tool in MDS.

BACKGROUND Multipotent mesenchymal stromal cells (MSCs) are widely used in the clinic due to their unique properties, namely, their ability to differentiate in all mesenchymal directions and their immunomodulatory activity. Healthy donor MSCs were used to prevent the development of acute graft vs host disease (GVHD) after allogeneic bone marrow transplantation (allo-BMT). The administration of MSCs to patients was not always effective. The MSCs obtained from different donors have individual characteristics. The differences between MSC samples may affect their clinical efficacy. AIM To study the differences between effective and ineffective MSCs. METHODS MSCs derived from the bone marrow of a hematopoietic stem cells donor were injected intravenously into allo-BMT recipients for GVHD prophylaxis at the moment of blood cell reconstitution. Aliquots of 52 MSC samples that were administered to patients were examined, and the same cells were cultured in the presence of peripheral blood mononuclear cells (PBMCs) from a third-party donor or treated with the pro-inflammatory cytokines IL-1β, IFN and TNF. Flow cytometry revealed the immunophenotype of the nontreated MSCs, the MSCs cocultured with PBMCs for 4 d and the MSCs exposed to cytokines. The proportions of CD25-, CD146-, CD69-, HLA-DR- and PD-1-positive CD4+ and CD8+ cells and the distribution of various effector and memory cell subpopulations in the PBMCs cocultured with the MSCs were also determined. RESULTS Differences in the immunophenotypes of effective and ineffective MSCs were observed. In the effective samples, the mean fluorescence intensity (MFI) of HLA-ABC, HLA-DR, CD105, and CD146 was significantly higher. After MSCs were treated with IFN or cocultured with PBMCs, the HLA-ABC, HLA-DR, CD90 and CD54 MFI showed a stronger increase in the effective MSCs, which indicated an increase in the immunomodulatory activity of these cells. When PBMCs were cocultured with effective MSCs, the proportions of CD4+ and CD8+central memory cells significantly decreased, and the proportion of CD8+CD146+ lymphocytes increased more than in the subpopulations of lymphocytes cocultured with MSC samples that were ineffective in the prevention of GVHD; in addition, the proportion of CD8+effector memory lymphocytes decreased in the PBMCs cocultured with the effective MSC samples but increased in the PBMCs cocultured with the ineffective MSC samples. The proportion of CD4+CD146+ lymphocytes increased only when cocultured with the inefficient samples. CONCLUSION For the first time, differences were observed between MSC samples that were effective for GVHD prophylaxis and those that were ineffective. Thus, it was shown that the immunomodulatory activity of MSCs depends on the individual characteristics of the MSC population.

A lower chemotherapeutic load and a small number of allogeneic BMTs did not affect total positive treatment results in adult patients with ALL, by complying with the principle achieving the continuity of cytostatic effects and by preserving the total cytostatic loading dose. The results of the Russian investigation casts some doubt on the necessity of using very intensive consolidation cycles and performing a large number of allogeneic BMTs in adult patients with ALL.

Introduction In most cases, haploidentical stem cell transplantation (haplo-HSCT) with negative depletion of α/β(+) T cells and CD19+ B lymphocytes from the graft is used to treat pediatric patients. The results are promising. However, the results of this method in adult patients is controversial. The accumulation of experience in haplo-HSCT with TCRαβ / CD19 + depletion in the group of adult patients is relevant. Aim Evaluation of the effectiveness and characterization of the most frequent complications in adult patients with hematological malignancies who underwent allo-HSCT from a haploidentical donor with depletion of TCRαβ/CD19 + cells. Patients and methods The analysis included 32 patients (14 males/18 females) with acute myeloid leukemia (AML, n=12), acute lymphoblastic leukemia (ALL, n=11), myelodysplastic syndrome (MDS, n = 6), chronic myeloid leukemia (CML, n = 1), primary myelofibrosis (PMF, n = 1), lymphoproliferative disease (LPD, n = 1). Median age was 28 years (range, 17-58). Disease status of acute leukemia at the beginning of pre-transplant conditioning was first complete remission (CR1) in 14 patients, CR2 in 7 and active disease in 2 patients. Pre-transplant conditioning regimen: RIC (Treosulfan 42 g/m2, Melphalan 140 mg/m2, Fludarabine 150mg/m2), MAC (Treosulfan 42 g / m2, Thiophosphamide 10 mg / kg, Fludarabine 150 mg / m2). Immunosuppressive therapy: Rituximab, Bortezomib, Tocilizumab, Abatacept. Immunomagnetic separation was performed using a CliniMACS Plus device. Descriptive statistics methods were used for analysis. The probabilities of survival and graft versus host disease (GVHD) rate were estimated using the Kaplan-Meier method. Results Log of TCRαβ + depletion was 1.61-5.33 (Me = 3.66). The median dose of CD34+ cells in transplant was 6.8 * 106/kg (range, 2.0-10.8). The median time to white blood cells recovery was +13 days after haplo-HSCT (range, 9-26). Median follow-up was 6.4 months. Transplant related mortality was 3.1%. Primary engraftment - 96.8%. Graft hypofunction - 16.2%. The probabilities of overall and disease-free survival for 12 months were 94.1% and 70,5%, respectively. The probability of relapse was 24.4% (Fig. 1). The probability of developing acute GVHD was 25%, GVHD rate was 18,75% including grade I (n=1), grade II (n=2), grade III (n=3) (data not shown). In 4 cases complete response was achieved with administration of first line immunosuppression therapy. 1 case (grade III GVHD) required administration of second line immunosuppression therapy - methylprednisolone, and the response was complete. 1 patient developed chronic GVHD. Nonclassical infectious complications prevail: viral infections (CMV, HHV6 and EBV) was 58.8%, fever with an unverified infectious agent was 15.6%, and tuberculosis in two cases (6.2%). Immunological events not associated with GVHD - 21.8% (TMA, TTP, myasthenia gravis, AIHA, PRCA). Conclusion In some cases, haplo-HSCT is the only HSCT option for an adult patient. The frequency of viral infectious complications and relapses in adult patients after haplo-HSCT TCRαβ / CD19 + depletion is comparable to the results in the pediatric population. Haplo-HSCT with TCRαβ / CD19 + depletion is characterized by minimal toxicity and a short period of myelotoxic agranulocytosis. Among the undesirable phenomena in the first place are infectious complications and frequent immunological events that do not fit into the criteria for GVHD, but affect the patient's quality of life and length of hospital stay. Figure 1 Disclosures Maschan: Miltenyi Biotec: Other: lecture fee.