ABSTRACT
Introduction. When studying COVID-19 pathology, considerable attention is paid to the damage to the respiratory and cardiovascular systems, which are associated with the manifestation of the infection. Data on changes in the organs of the lymphatic system are yet scarce. To date, COVID-19 is sure to cause the dysfunction of the immune system;however, information about the damage to the lymph nodes is ambigu-ous. The aim of the study was to characterize morphological changes in the hilar lymph nodes of patients who died from a new coronavirus infection COVID-19 in Vladivostok in 2021. Materials and methods. A morphological study of the lymph nodes was performed in 20 patients who died from the new coronavirus infection, diagnosed in vivo using a PCR test. The controls were patients who did not have diseases of the hematopoietic and lymphoid tissue in their medical histories but who died a violent death. The material for histological examination was processed according to generally accepted methods. Results. In all patients, we identified lymphadenopathy with hypoplasia of lymphoid tissue of varying se-verity. In the cortex, lymphatic follicles were detected, mainly without light (germinal) centers, as well as follicles with a pronounced rarefaction of cells and exposure to the reticular stroma, with no visualization of the paracortical zone. According to the severity of reactive changes in the T-and B-dependent zones of the lymph nodes, we distinguished two types of lymphadenopathy: 1) mixed follicular type;2) follicular involution with lymphoid depletion. Conclusion. Pathological changes in the hilar lymph nodes of the lungs in patients who died from COVID-19 indicated immunosuppressive effects of the SARS-CoV-2. The pathologic changes in lymph nodes mani-fested with lymphocytic depletion in T-and B-dependent zones. This indicates a deficiency of cellular and humoral immunity in moderate and severe COVID-19. © 2022, MDV Group. All rights reserved.
ABSTRACT
One of the most important requirements for the personnel of microbiological laboratories working with pathogenic and infectious agents is the observance of precautionary measures and the implementation of a set of preventive measures, collectively interpreted as biological safety (biosafety). To a large extent, biosafety problems are also relevant for all clinical laboratories working with biosubstrates, with the potential threat of containing pathogens of bloodborne infections in them. On December 30, 2020, the President of the Russian Federation signed Federal Law â 492 «On the Biological Safety of the Russian Federation¼ (â 492-FZ), which regulates the basic legal norms and regulation of biosafety issues, as well as a list of measures to prevent the risks of the spread of infections due to accidents, bioterrorist acts and sabotage. The current pandemic of the coronavirus infection COVID-19 has demonstrated, on the one hand, the epidemiological vulnerability of the single world space, and on the other hand, the decisive influence of biological emergencies on the emergence of negative political and economic processes in the world community. In this regard, the issues of ensuring biosafety in the work of microbiological laboratories in the context of protecting personnel and the environment from accidental or unintentional spread of infections are relevant. Working with pathogenic biological agents in microbiological laboratories is constantly associated with the risk of accidents and possible laboratory infection (laboratory-acquired infections) of employees, environmental pollution if the requirements of regulatory documents on biological safety are not met. In accordance with the requirements of â 492-FZ, in order to prevent biological threats, it is necessary to create a system for monitoring biological risks in microbiological laboratories when working with any infected material.
Subject(s)
COVID-19 , Laboratory Infection , COVID-19/epidemiology , COVID-19/prevention & control , Containment of Biohazards , Humans , Laboratories , Laboratory Infection/epidemiology , Laboratory Infection/prevention & control , PandemicsABSTRACT
Rapid development in 2020 of the COVID-19 pandemic caused by SARS-CoV-2 initially indicated signifi-cant involvement of the immune system. However, information on specific changes in organs of the immune system is still limited. A wide range of alterations was revealed in our study: from pronounced devastation of B-dependent and T-dependent zones of lymphoid tissue, reminiscent of changes in HIV infection at the AIDS stage, to hyperplasia of the tissue of lymph nodes and spleen of varying degrees. Analyzing the literature data, we focused on the fact that pathomorphological changes revealed in the autopsy studies of patients with a severe COVID-19 were accompanied by premortal lymphopenia in most cases. However, the cause of lymphopenia in COVID-19 has not yet been disclosed, authors of the review hypothesized that unregulated apoptosis of circulating lymphocytes is one of the potential lymphopenia inductors. Cytokine activation (“cytokine storm”) may be associated with lymphoid organs’ atrophy, which also contributes to a decrease in the circulating lymphocyte count. There is no doubt about the relevance of further identification of the immune cell apoptosis as one of the causes of lymphopenia and immune dysfunction in COVID-19 patients, which has prospects for pharmacological developments to manage lymphocytic apoptosis. © 2021, MDV Group. All rights reserved.