Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal stem cell disorder characterized by partial or absolute deficiency of glycophosphatidyl-inositol (GPI) anchor-linked surface proteins on blood cells. A lack of precise diagnostic standards for flow cytometry has hampered useful comparisons of data between laboratories. We report data from the first study evaluating the reproducibility of high-sensitivity flow cytometry for PNH in Russia. PNH clone sizes were determined at diagnosis in PNH patients at a central laboratory and compared with follow-up measurements in six laboratories across the country. Analyses in each laboratory were performed according to recommendations from the International Clinical Cytometry Society (ICCS) and the more recent 'practical guidelines'. Follow-up measurements were compared with each other and with the values determined at diagnosis. PNH clone size measurements were determined in seven diagnosed PNH patients (five females, two males: mean age 37 years); five had a history of aplastic anemia and three (one with and two without aplastic anemia) had severe hemolytic PNH and elevated plasma lactate dehydrogenase. PNH clone sizes at diagnosis were low in patients with less severe clinical symptoms (0.41-9.7% of granulocytes) and high in patients with severe symptoms (58-99%). There were only minimal differences in the follow-up clone size measurement for each patient between the six laboratories, particularly in those with high values at diagnosis. The ICCS-recommended high-sensitivity flow cytometry protocol was effective for detecting major and minor PNH clones in Russian PNH patients, and showed high reproducibility between laboratories.

The aggressive infectious nature of SARS-CoV-2, its rapid spread, and the emergence of mutations necessitate investigation of factors contributing to differences in SARS-CoV-2 susceptibility and severity. The role of genetic variations in the human HLA continues to be studied in various populations in terms of both its effect on morbidity and clinical manifestation of illness. The study included 484 COVID-19 convalescents (northwest Russia residents of St. Petersburg). Cases in which the responsible strain was determined were divided in two subgroups: group 1 (n = 231) had illness caused by genovariants unrelated to variant of concern (VOC) strains; and group 2 (n = 80) had illness caused by the delta (B.1.617.2) VOC; and a control group (n = 1456). DNA typing (HLA-A, B, DRB1) was performed at the basic resolution level. HLA-A*02 was associated with protection against infection caused by non-VOC SARS-CoV-2 genetic variants only but not against infection caused by delta strains. HLA-A*03 was associated with protection against infection caused by delta strains; and allele groups associated with infection by delta strains were HLA-A*30, B*49, and B*57. Thus, in northwest Russia, HLA-A*02 was associated with protection against infection caused by non-VOC SARS-CoV-2 genetic variants but not against delta viral strains. HLA-A*03 was associated with a reduced risk of infection by delta SARS-CoV-2 strains. HLA-A*30, HLA-B*49, and HLA-B*57 allele groups were predisposing factors for infection by delta (B.1.617.2) strains.

During the pandemic, a large number of works devoted to COVID infection have appeared, which have made it possible to understand the pathogenetic features of the disease and to accumulate significant clinical experience. However, the question remains about the degree of participation of humoral and cellular (primarily T-cell) immunity in the mechanisms of immune defense and resistance to COVID-19, the individual features of the immune response in different subjects. Post-COVID syndrome is currently a separate diagnosis included in the ICD-10 International Classification of Diseases, but the long-term effects of the SARS-CoV-2 on the immune system are not yet well established. At the same time, a long-term increased activity of the immune system can contribute to the development of autoimmune reactions. The review of the literature presents the results of studies, mainly devoted to immune system disorders after COVID infection. The changes in subpopulations of T-lymphocytes, B-lymphocytes, their functional properties, the complement system and other factors of humoral immunity, as well as the production of a number of cytokines are described. Data on immune disorders in post-COVID syndrome and during the convalescence period are presented in detail. Since COVID-19 is an infection that has a significant impact on the hematopoietic system and hemostasis, special attention is paid to the category of subjects with an increased risk of severe complications. Among the latter are elderly patients, persons suffering from diabetes mellitus, oncological and oncohematological patients, in particular, with hematopoietic and lymphoid tissue neoplasia, such as chronic lymphocytic leukemia, lymphoma, multiple myeloma. The review pays special attention to the peculiarities of the course of COVID-19 and the response of the immune system to vaccination in patients with oncohematological diseases. Deciphering the significance of individual links of cellular and humoral immunity in patients who have undergone COVID-19 is an important issue in creating effective vaccines and improving therapeutic methods.

Annually a number of tissue typing laboratories (HLA-laboratories) of Russian Federation, performing examinations of potential donors and recipients of organs and tissues, participate in the implementation of international external professional testing of HLA-typing organized by the European Federation for Immunogenetics (EFI), since the external control program currently do not exist in our country. The aim of this study was to analyze the effectiveness of the implementation of external professional testing of HLA-typing by laboratories of Russian Federation from 2017 to 2022. Materials and methods. During this period, from 10 to 16 laboratories of our country took part in the external professional testing of HLA-typing annually. The control trials were organized by the Department of Transfusion Medicine of the Medical University of Vienna (Austria) performing this function under the auspices of the EFI. For research, 10 DNA samples isolated from nucleated peripheral blood cells of healthy blood donors were provided. According to the standards of the EFI, the typing of HLA genes must be performed by all molecular methods used in the laboratory. Participating laboratories presented the low and (or) high/allelic resolution results. Results. Our analysis showed that during 2017—2019 11.1—28.6% of Russian laboratories failed to perform the low resolution HLA-typing. From 2020 to 2022, the results of all laboratories were considered satisfactory in accordance with EFI standards. Successful implementation of the high/allelic resolution HLA typing by all laboratories was noted only in 2018. During the remaining five years of observation, the results from 10% to 33.3% of Russian laboratories were not successful according to EFI quality standards. Conclusion. The analysis identified the need for the constant participation of HLA typing laboratories in the external professional testing of HLA-typing, as well as the development and implementation of Russian system of external HLA typing quality control and the organization of continuous education of tissue typing laboratory specialists in our country.