Features of the Immune Response in COVID-19

BACKGROUND This review is devoted to the analysis of the features of the immune response in COVID-19. The review indicates the clinical manifestations of COVID-19, modern data on the immunopathogenesis of the disease and its complications are considered. AIM OF STUDY To clarify some pathogenetic mechanisms of the immune response in COVID-19, which can help in creating an algorithm for examining patients for early prognosis and prevention of severe course and complications of the disease. MATERIAL AND METHODS To achieve this goal, the results of domestic and foreign scientific studies on the pathogenesis, diagnosis and treatment of COVID-19 were analyzed. The literature search was carried out in electronic search engines Scopus and PubMed. For the analysis, scientific articles published in the period from 2019 to 2021 were selected;88% of analyzed works are not older than 5 years. CONCLUSION The late production of type I IFN, an increase in the level of pro-inflammatory monocytes, a decrease in the expression of HLA-DR on monocytes, violation of the presentation of the virus and the formation of specific lymphocytes, the death of T-lymphocytes and profound immunosuppression are of greatest importance for the development of a severe form of COVID-19. © 2023 Sklifosovsky Research Institute for Emergency Medicine. All rights reserved.

Alterations in the CD56- and CD56+ T Cell Subsets during COVID-19.

The effectiveness of the antiviral immune response largely depends on the activation of cytotoxic T cells. The heterogeneous group of functionally active T cells expressing the CD56 molecule (NKT-like cells), that combines the properties of T lymphocytes and NK cells, is poorly studied in COVID-19. This work aimed to analyze the activation and differentiation of both circulating NKT-like cells and CD56- T cells during COVID-19 among intensive care unit (ICU) patients, moderate severity (MS) patients, and convalescents. A decreased proportion of CD56+ T cells was found in ICU patients with fatal outcome. Severe COVID-19 was accompanied by a decrease in the proportion of CD8+ T cells, mainly due to the CD56- cell death, and a redistribution of the NKT-like cell subset composition with a predominance of more differentiated cytotoxic CD8+ T cells. The differentiation process was accompanied by an increase in the proportions of KIR2DL2/3+ and NKp30+ cells in the CD56+ T cell subset of COVID-19 patients and convalescents. Decreased percentages of NKG2D+ and NKG2A+ cells and increased PD-1 and HLA-DR expression levels were found in both CD56- and CD56+ T cells, and can be considered as indicators of COVID-19 progression. In the CD56- T cell fraction, increased CD16 levels were observed in MS patients and in ICU patients with lethal outcome, suggesting a negative role for CD56-CD16+ T cells in COVID-19. Overall, our findings suggest an antiviral role of CD56+ T cells in COVID-19.

INTERRELATIONS BETWEEN VIRAL LOAD AND CELLULAR IMMUNITY IN PATIENTS WITH COVID-19 OF VARYING SEVERITY.

Assessment of viral load levels in various biological samples taken from the respiratory tract can be an indicator of an ongoing process of active viral replication and may be used to monitor severe respiratory viral infections. The study of the relationship between SARS-CoV-2 viral load and immunological laboratory parameters is an important step in the search for clinical markers of COVID-19. The aim of this research was to quantify viral load in patients with COVID-19 and to identify the relationship between viral load and changes in the parameters of the cellular component of the immune system. A laboratory examination was carried out on 74 patients diagnosed with COVID-19, they were divided into 3 groups based on the severity of the disease: mild, moderate, severe. Total viral load in clinical samples was determined by the number of SARS-CoV-2 RNA copies per 100 copies of the reference RNaseP gene. A comprehensive assessment of the cellular component of the immune system was performed using flow cytometry and direct monoclonal antibodies, and the IL-6, and C-reactive protein concentrations were determined. We revealed a relationship between the development of serious clinical conditions in the patients with COVID-19, and the levels of viral load. High levels of viral RNA in biological samples correlate with main indicators of the T cell component of the immune system associated with disease severity. In a subgroup of patients with an extremely high viral load, strong positive correlations were found between the relative numbers of cytotoxic lymphocytes (CD3+CD8+), activated T lymphocytes (CD3+HLA-DR+), as well as absolute and relative numbers of activated B lymphocytes and NK cells (CD3-CD25+). Laboratory monitoring of the cellular component of the immune system, along with the assessment of viral loads, should improve early assessment of clinical condition in the patients with COVID-19. Changes in expression levels of activation markers on immune cells can be potentially viewed as indicators of recovery during COVID-19.Copyright © Nikitin Yu.V. et al., 2023 The article can be used under the Creative Commons Attribution 4.0 License.

HIGH RNAemia ASSOCIATES WITH SKEWED T-CELL RESPONSE IN PLWH HOSPITALIZED FOR COVID-19

Background: Severe COVID-19 outcomes have been reported in people living with HIV (PLWH). High SARS-CoV-2 RNAemia has emerged as a hallmark of severe COVID-19, yet its pathogenic role in the context of COVID-19 in PLWH is currently unknown. We hereby measured SARS-CoV-2 RNAemia and explored its association with T-cell/humoral responses and clinical severity in PLWH. Method(s): Unvaccinated PLWH and age/sex-matched people living without HIV (PLWOH) hospitalized for radiologically-confirmed COVID-19 pneumonia were consecutively enrolled (March 2020-January 2021). We measured: SARS-CoV-2 RNAemia (RT-qPCR);T-cell activation (HLA-DR+CD-38+), cytotoxic T-cells [granzyme-B(GRZB)+perforin(PRF)+], GRZB/PRF production (MFI) by cytotoxic T-cells (flow cytometry);SARS-CoV-2-specific cytokines (IFN-gamma/ TNF-alpha/IL-2/IL-4/IL-17A)-producing T-cells, after SARS-CoV-2 spike peptides challenge (flow cytometry);anti-RBD antibodies (ELISA), Spike-ACE2 binding inhibition (receptor binding inhibition assay). Statistics: Mann-Whitney test and Spearman's correlation. Result(s): 18 PLWH (16 on cART;median CD4 361.5/mL;HIV-RNA< 50 cp/ mL in 15/18) and 18 PLWOH were included at a median of 10 days from symptoms onset (Fig.1A). PLWH had lower PaO2/FiO2 [140 (122-151.5) vs. 207 (156.3-309.3);P=0.0005] and higher SARS-CoV-2 RNAemia (Fig.1B). While humoral responses were comparable between groups ( Fig.1C-D), as was T-cell activation, PLWH showed skewed T-cell responses: higher perforin production by cytotoxic T-cells (Fig.1E);fewer SARS-CoV-2-specific IFN-gamma+ and IL-4+ CD4 T-cells (Fig.1F);lower Th1 tri-functional (IFN-gamma+TNF-alpha+IL-2+) and bi-functional (IFN-gamma+TNF-alpha+) CD4 T-cells (Fig.1G);reduced TNF-alpha+ CD8 T-cells (Fig.1H). Interestingly, SARS-CoV-2 RNAemia correlated negatively with PaO2/FiO2 nadir and SARS-CoV-2-specific T-cells, yet positively with perforin production by cytotoxic T-cells (Fig.1I-M). No correlations between RNAemia and humoral responses were found. Conclusion(s): As compared to HIV-uninfected patients, PLWH hospitalized for COVID-19 pneumonia feature high SARS-CoV-2 RNAemia which is linked to respiratory failure and skewed T-cell responses, with higher perforin production by cytotoxic T-cells, and yet fewer polyfunctional SARS-CoV-2-specific T-cells. Our data suggest a link between HIV-related T-cell dysfunction and poor control over circulating SARS-CoV-2 that may in turn influence COVID-19 severity in PLWH. (Figure Presented).

Immune dysregulation in hospitalized COVID-19 patients is associated with worse clinical outcome

Background: COVID-19 is a viral disease affecting mostly respiratory system with variable severity of the clinical course. Several clinical and laboratory parameters are associated with poor outcome. Progression of the clinical stage is associated with the exaggerated immune response and the cytokine storm. Method(s): We focused on the search of potential prognostic markers of fatal outcome among immune parameters. To this end, we examined the immune profile in 823 COVID-19 patients hospitalized in University Teaching Hospital in Martin (Slovakia) on admission and its changes over time during the first week of hospitalization. The examined immune profile consisted of the differential blood cell counts, serum concentration of immunoglobulins and basic complement compounds C4 and C3, flow cytometric lymphocyte subsets phenotyping and the measurement of selected activation and inhibition markers. Result(s): Although none of examined parameters alone had sufficient AUC value to be considered as a marker of (un)favourable outcome, we found several significant differences among different severity groups of patients, as well as between survivors and non-survivors. Severity of COVID-19 correlated with the severity of neutrophilia, thrombocytopenia, depletion of leukocyte (except for neutrophils) and lymphocyte subsets. In comparison to the fatal outcome, survival was associated with higher concentration of C3 and IgM, lower proportion of CD8+CD38+ cells, higher proportion of CD8+NKG2A+ and NK NKG2A+ cells on admission and with the significant increase in the expression on HLA-DR on both CD3+ and CD8+ cells over the first week. Conclusion(s): Our results point out to the dysregulated functional status of depleted CD8+ cells with their over-activation and possibly insufficient compensatory inhibition in COVID-19 non-survivors. Based on our results, the increase in HLA-DR expression on CD3+ and CD8+ cells is necessary for recovery.

HLA binding-groove motifs are associated with myocarditis induction after Pfizer-BioNTech BNT162b2 vaccination

We found a higher incidence of myocarditis in young males who had received Pfizer-BioNTech BNT162b2 vaccinations as compared with historical controls and unvaccinated individuals. The analyses focused on risk following the first and second vaccine in adults and adolescents, as well as risk in adults following the third (booster) vaccine. Males, mainly aged 12-30 years, were found to be at higher risk. However, the question remains what causes lead one specific young male, but not another, to develop post-vaccination myocarditis. The HLA molecule is known to play an important role in infectious and auto-inflammatory diseases. We hypothesized that differences in HLA alleles could lead to either protection or susceptibility to vaccination-induced myocarditis. On this basis, HLA typing was performed using next-generation sequencing technology for the HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1 loci, in 21 wellcharacterized patients who developed myocarditis after the second Pfizer BNT162b2 vaccination. The HLA genotypes were compared with high-resolution HLA data of 272 healthy controls from the Hadassah Bone Marrow registry samples, who are representative of HLA frequencies in the Israeli population. Our findings demonstrated that in HLA class II, DRB1*14:01 (19.04% vs. 5.3%, Pcorr = 0.028, OR = 4.17), HLA-DQB1*05:03 (19.04% vs. 6.06%, Pcorr = 0.034, OR = 3.64) and DRB1*15:03 (7.14% vs. 0.0%, Pcorr = 0.003, OR = 41.76) were significantly associated with disease susceptibility. We further discovered susceptibility motifs in the HLA-DR peptidebinding grooves: His60 (Pcorr0.01, OR = 3.52) and Arg70 (Pcorr = 0.0047, OR = 3.43). Our findings suggest that immunogenetic fingerprints in HLA peptide-binding grooves may have changed the binding affinity of different peptides derived from the Pfizer-BioNTech BNT162b2 vaccination, and induced myocarditis.

Impact of SARS-CoV-2 on HLA serological phenotyping level in southern Portuguese solid organ donors

HLA molecules play a key role in transplant medicine and disease pathogenesis, being a useful tool in predicting disease progression and identifying potential solid organ donors (SOD). The Coronavirus disease 2019 (SARS-CoV-2) pandemic had a huge worldwide impact, which strongly affected the activity of different transplant programs. So far, it has been shown that HLA type may be a crucial differentiator between individuals who have varying occurrence, morbidity, and mortality response to SARS-CoV-2. In this work, we investigated if differences in the frequency of SOD HLA alleles, were impacted during SARS-CoV-2 pandemic. We performed a retrospective file audit of all HLA-typings done in 2 subsets of SOD pre-pandemic period (ppp) (n = 379) and pandemic period (pp) (n = 351), collected in equivalent timeframes. We discuss data for the major HLA-A, HLA-B, HLA-C, and HLA-DRB1 allele groups at serological phenotyping level. Overall, there was a 7% SOD decrease in the pp. Considering both periods, the most common allele groups were HLA-A2, HLA-B35, HLA-Cw7, HLA-DR7 and HLA-DQ2. For the ppp group, the most common alleles were HLA-A2, HLA-B35, HLA-Cw7, HLADR13 and HLA-DQ2, while in the pp group the most common alleles were HLA-A2, HLA-B44, HLA-Cw7, HLA-DR4 and HLA-DQ2. When comparing both populations at the serological phenotyping level an increased in relative frequency was found for 10, 12, 8, 8 and 2, and a decreased was found for 10, 24, 8, 6 and 5 for HLA-A, -B, -C, -DR and -DQ, respectively. The significant variation within the HLA frequencies between the different pre-pandemic and pandemic groups highlights the value of population-specific HLA-typing. Furthermore, the identification of different frequencies among both populations will impact in patients HLA compatibility with SOD thus impacting their transplantability.

SUBPOPULATION COMPOSITION OF PERIPHERAL BLOOD LYMPHOCYTES IN COVID-19.

The pathogenesis of severe coronavirus infection COVID-19 is associated with activation of immune system, cytokine storm, impaired blood clotting, microvascular thrombosis, organ ischemia and multiple organ dysfunction syndrome. The role of various lymphocyte subpopulations in COVID-19 is still debated. The aim of our study was to analyze the subpopulational profile of peripheral blood lymphocytes in COVID-19 patients as compared with healthy donors. The study included 20 COVID-19 patients (11 males and 9 females,) and 26 healthy donors. Average age of the patients was 52 and 56 years, respectively. Clinical examinations were performed by standard laboratory methods. Peripheral blood lymphocytes were isolated in the Ficoll gradient. The cells were stained with antibodies to specific antigens of main lymphocyte populations, endothelial cells, and apoptotic cell markers. The analysis was performed by flow cytometry. The results showed that all patients had elevated C-reactive protein (14- to 35-fold), ferritin (1.2- to 13-fold), D-dimers (1.2- to 90-fold). 55% of men had a decrease in the absolute number of lymphocytes, in women this index was at the low normal limit. Cytometric analysis showed that, among peripheral blood lymphocytes, the proportion of functional cells expressing the CD45 marker ranged from 2 to 12% in 70% of patients, as compared with 80-99% among the donors. The proportion of CD45+ lymphocytes significantly correlated with the level of hemoglobin, but not with the levels of inflammatory biochemical markers. Among the functional lymphocytes of patients, there was a decrease in the proportion of CD3+, CD4+, CD8+T cells, increased proportion of natural killer CD56+ and the apoptotic (AnnexinV+) cell contents, but the proportion of CD19 and HLA-DR+B cells was not changed. Analysis of the lymphocyte (LC) subpopulations that did not express CD45 marker showed that this fraction contained different lymphocyte subsets with reduced expression of CD4, CD8, CD19, CD56 etc. in the blood of patients and donors. Higher percentage of endothelial cells expressing CD62P marker made the difference between patients and donors. Laboratory determination of lymphocyte subsets in blood samples of COVID-19 patients does not reflect the real severity pattern of the disease, thus requiring studies of the CD45-expressing functional cell populations.Copyright © Svirshchevskaya E.V. et al., 2023 The article can be used under the Creative Commons Attribution 4.0 License.

INTERRELATIONS BETWEEN VIRAL LOAD AND CELLULAR IMMUNITY IN PATIENTS WITH COVID-19 OF VARYING SEVERITY.

Assessment of viral load levels in various biological samples taken from the respiratory tract can be an indicator of an ongoing process of active viral replication and may be used to monitor severe respiratory viral infections. The study of the relationship between SARS-CoV-2 viral load and immunological laboratory parameters is an important step in the search for clinical markers of COVID-19. The aim of this research was to quantify viral load in patients with COVID-19 and to identify the relationship between viral load and changes in the parameters of the cellular component of the immune system. A laboratory examination was carried out on 74 patients diagnosed with COVID-19, they were divided into 3 groups based on the severity of the disease: mild, moderate, severe. Total viral load in clinical samples was determined by the number of SARS-CoV-2 RNA copies per 100 copies of the reference RNaseP gene. A comprehensive assessment of the cellular component of the immune system was performed using flow cytometry and direct monoclonal antibodies, and the IL-6, and C-reactive protein concentrations were determined. We revealed a relationship between the development of serious clinical conditions in the patients with COVID-19, and the levels of viral load. High levels of viral RNA in biological samples correlate with main indicators of the T cell component of the immune system associated with disease severity. In a subgroup of patients with an extremely high viral load, strong positive correlations were found between the relative numbers of cytotoxic lymphocytes (CD3+CD8+), activated T lymphocytes (CD3+HLA-DR+), as well as absolute and relative numbers of activated B lymphocytes and NK cells (CD3-CD25+). Laboratory monitoring of the cellular component of the immune system, along with the assessment of viral loads, should improve early assessment of clinical condition in the patients with COVID-19. Changes in expression levels of activation markers on immune cells can be potentially viewed as indicators of recovery during COVID-19.Copyright © Nikitin Yu.V. et al., 2023 The article can be used under the Creative Commons Attribution 4.0 License.

T HELPER CELL SUBSETS AND RELATED TARGET CELLS IN ACUTE COVID-19.

Current review presents a brief overview of the immune system dysregulation during acute COVID-19 and illustrates the main alterations in peripheral blood CD4+ T-cell (Th) subsets as well as related target cells. Effects of dendritic cell dysfunction induced by SARS-CoV-2 exhibited decreased expression of cell-surface HLA-DR, CCR7 as well as co-stimulatory molecules CD80 and CD86, suggesting reduced antigen presentation, migratory and activation capacities of peripheral blood dendritic cells. SARS-CoV-2-specific Th cells could be detected as early as days 2-4 post-symptom onset, whereas the prolonged lack of SARS-CoV-2-specific Th cells was associated with severe and/or poor COVID-19 outcome. Firstly, in acute COVID-19 the frequency of Th1 cell was comparable with control levels, but several studies have reported about upregulated inhibitory immune checkpoint receptors and exhaustion-associated molecules (TIM3, PD-1, BTLA, TIGIT etc.) on circulating CD8+ T-cells and NK-cells, whereas the macrophage count was increased in bronchoalveolar lavage (BAL) samples. Next, type 2 immune responses are mediated mainly by Th2 cells, and several studies have revealed a skewing towards dominance of Th2 cell subset in peripheral blood samples from patients with acute COVID-19. Furthermore, the decrease of circulating main Th2 target cells - basophiles and eosinophils - were associated with severe COVID-19, whereas the lung tissue was enriched with mast cells and relevant mediators released during degranulation. Moreover, the frequency of peripheral blood Th17 cells was closely linked to COVID-19 severity, so that low level of Th17 cells was observed in patients with severe COVID-19, but in BAL the relative number of Th17 cells as well as the concentrations of relevant effector cytokines were dramatically increased. It was shown that severe COVID-19 patients vs. healthy control had higher relative numbers of neutrophils if compared, and the majority of patients with COVID-19 had increased frequency and absolute number of immature neutrophils with altered ROS production. Finally, the frequency of Tfh cells was decreased during acute COVID-19 infection. Elevated count of activated Tfh were found as well as the alterations in Tfh cell subsets characterized by decreased "regulatory" Tfh1 cell and increased "pro-inflammatory" Tfh2 as well as Tfh17 cell subsets were revealed. Descriptions of peripheral blood B cells during an acute SARS-CoV-2 infection werev reported as relative B cell lymphopenia with decreased frequency of "naive" and memory B cell subsets, as well as increased level of CD27hiCD38hiCD24- plasma cell precursors and atypical CD21low B cells. Thus, the emerging evidence suggests that functional alterations occur in all Th cell subsets being linked with loss-of-functions of main Th cell subsets target cells. Furthermore, recovered individuals could suffer from long-term immune dysregulation and other persistent symptoms lasting for many months even after SARS-CoV-2 elimination, a condition referred to as post-acute COVID-19 syndrome.Copyright © 2022 Saint Petersburg Pasteur Institute. All rights reserved.

Characterization of Mesenchymal Cell from BAL of post COVID-19 patient whit fibrosis

Increasing number of severe COVID 19 patients develop pulmonary Fibrosis, but the management of this complication is still unclear due to a lack of clinical trials. Aim of this study was to characterize mesenchymal cells (MC) isolated from 10 broncho-alveolar lavage (BAL, at 2 months after discharge) from patients with COVID19 fibrosis (COVID19-f) and to compare them with those isolated from 8 patients with collagen tissue diseaseassociated interstitial fibrosis(CTD-ILD). BAL fluid (BALf) levels of TGFbeta, VEGF, TIMP2, RANTES, IL6, IL8, and PAI1 were assessed by ELISA. Primary MC foci were cultured and expanded in D-MEM +10% FBS, characterized by flow cytometry and osteogenic and adipogenic differentiation. Collagen 1 production (+/-TGF-beta) was tested by WB and mRNA expression. BALf cytokine and GF levels were comparable in the two groups. Efficiency of MC isolation from BAL was 100% in COVID-f compared to 65% in CTD-ILD. MC antigen surface expression of CD105, CD73, CD90 (>90%, respectively), CD45, CD34, CD19 and HLA-DR (<5%, respectively) was comparable. None of MC samples differentiated in adipocytes, while COVID19-f were positive for calcium deposition. COVID19-f MC showed at WB, higher Collagen 1 production with respect to CTD-ILD with TGF-beta stimulation. Our preliminary data suggest MC from COVID19-f share several features with CTD-ILD but might have a higher response to fibrogenic and differentiation signals.

A case of subacute thyroiditis after influenza vaccination

A 40-year-old Japanese woman presented to the outpatient clinic with fever and palpitations 2 days after receiving the influenza vaccine (Influenza HA Vaccine 'KMB') following the second dose of coronavirus disease 2019 (COVID-19) vaccine (COVID-19 vaccine Moderna intramuscular injection). At the first visit, the patient presented with a swollen thyroid gland with mild tenderness, and she was diagnosed with subacute thyroiditis (SAT) based on the presence of thyrotoxicosis (free T3: 5.42 pg/mL;free T4: 2.34 ng/dL;and thyroid-stimulating hormone (TSH): <0.01 muIU/mL), a high C-reactive protein level (5.77 mg/dL), a negative TSH receptor antibody, and characteristic ultrasound findings. The patient's human leukocyte antigen types were A2, A11, B35, B51, DR4, and DR1403. Prednisolone (15 mg/day) was given as an initial dose, after which the fever subsided, and the dose was tapered and discontinued after 6 weeks. The patient was thought to have developed SAT due to influenza vaccination. SAT after influenza vaccination may be overlooked. For patients with SAT, it is necessary to obtain information regarding their vaccination history.Copyright © 2023 The authors.

Kinetics of CD169, HLA-DR, and CD64 expression as predictive biomarkers of SARS-CoV2 outcome.

INTRODUCTION: Discriminating between virus-induced fever from superimposed bacterial infections is a common challenge in intensive care units. Superimposed bacterial infections can be detected in severe SARS-CoV2-infected patients, suggesting the important role of the bacteria in COVID-19 evolution. However, indicators of patients' immune status may be of help in the management of critically ill subjects. Monocyte CD169 is a type I interferon-inducible receptor that is up-regulated during viral infections, including COVID-19. Monocyte HLA-DR expression is an immunologic status marker, that decreases during immune exhaustion. This condition is an unfavorable prognostic biomarker in septic patients. Neutrophil CD64 upregulation is an established indicator of sepsis. METHODS: In this study, we evaluated by flow cytometry the expression of cellular markers monocyte CD169, neutrophil CD64, and monocyte HLA-DR in 36 hospitalized patients with severe COVID-19, as possible indicators of ongoing progression of disease and of patients' immune status. Blood testings started at ICU admission and were carried on throughout the ICU stay and extended in case of transfer to other units, when applicable. The marker expression in mean fluorescence intensity (MFI) and their kinetics with time were correlated to the clinical outcome. RESULTS: Patients with short hospital stay (≤15 days) and good outcome showed higher values of monocyte HLA-DR (median 17,478 MFI) than long hospital stay patients (>15 days, median 9590 MFI, p= 0.04) and than patients who died (median 5437 MFI, p= 0.05). In most cases, the recovery of the SARS-CoV2 infection-related signs was associated with the downregulation of monocyte CD169 within 17 days from disease onset. However in three surviving long hospital stay patients, a persistent upregulation of monocyte CD169 was observed. An increased neutrophil CD64 expression was found in two cases with a superimposed bacterial sepsis. CONCLUSION: Monocyte CD169, neutrophil CD64, and monocyte HLA-DR expression can be used as predictive biomarkers of SARS-CoV2 outcome in acutely infected patients. The combined analysis of these indicators can offer a real-time evaluation of patients' immune status and of viral disease progression versus superimposed bacterial infections. This approach allows to better define the patients' clinical status and outcome and may be useful to guide clinicians' decisions. Our study focused on the discrimination between the activity of viral and bacterial infections and on the detection of the development of anergic states that may correlate with an unfavorable prognosis.

T HELPER CELL SUBSETS AND RELATED TARGET CELLS IN ACUTE COVID-19

Current review presents a brief overview of the immune system dysregulation during acute COVID-19 and illustrates the main alterations in peripheral blood CD4+ T-cell (Th) subsets as well as related target cells. Effects of dendritic cell dysfunction induced by SARS-CoV-2 exhibited decreased expression of cell-surface HLA-DR, CCR7 as well as co-stimulatory molecules CD80 and CD86, suggesting reduced antigen presentation, migratory and activation capacities of peripheral blood dendritic cells. SARS-CoV-2-specific Th cells could be detected as early as days 2–4 post-symptom onset, whereas the prolonged lack of SARS-CoV-2-specific Th cells was associated with severe and/or poor COVID-19 outcome. Firstly, in acute COVID-19 the frequency of Th1 cell was comparable with control levels, but several studies have reported about upregulated inhibitory immune checkpoint receptors and exhaustion-associated molecules (TIM3, PD-1, BTLA, TIGIT etc.) on circulating CD8+ T-cells and NK-cells, whereas the macrophage count was increased in bronchoalveolar lavage (BAL) samples. Next, type 2 immune responses are mediated mainly by Th2 cells, and several studies have revealed a skewing towards dominance of Th2 cell subset in peripheral blood samples from patients with acute COVID-19. Furthermore, the decrease of circulating main Th2 target cells — basophiles and eosinophils — were associated with severe COVID-19, whereas the lung tissue was enriched with mast cells and relevant mediators released during degranulation. Moreover, the frequency of peripheral blood Th17 cells was closely linked to COVID-19 severity, so that low level of Th17 cells was observed in patients with severe COVID-19, but in BAL the relative number of Th17 cells as well as the concentrations of relevant effector cytokines were dramatically increased. It was shown that severe COVID-19 patients vs. healthy control had higher relative numbers of neutrophils if compared, and the majority of patients with COVID-19 had increased frequency and absolute number of immature neutrophils with altered ROS production. Finally, the frequency of Tfh cells was decreased during acute COVID-19 infection. Elevated count of activated Tfh were found as well as the alterations in Tfh cell subsets characterized by decreased "regulatory” Tfh1 cell and increased "pro-inflammatory” Tfh2 as well as Tfh17 cell subsets were revealed. Descriptions of peripheral blood B cells during an acute SARS-CoV-2 infection werev reported as relative B cell lymphopenia with decreased frequency of "naïve” and memory B cell subsets, as well as increased level of CD27hiCD38hiCD24– plasma cell precursors and atypical CD21low B cells. Thus, the emerging evidence suggests that functional alterations occur in all Th cell subsets being linked with loss-of-functions of main Th cell subsets target cells. Furthermore, recovered individuals could suffer from long-term immune dysregulation and other persistent symptoms lasting for many months even after SARS-CoV-2 elimination, a condition referred to as post-acute COVID-19 syndrome.

A CASE OF LONG-TERM TOLERANCE AFTER KIDNEY TRANSPLANTATION.

We present a case of long-term organ functioning (ca.10 years) after allografting of a cadaveric kidney without usage of immunosuppressing drugs. In 2005, a patient suffering from a hypertensive form of chronic glomerulonephritis, have received an allogeneic graft of cadaveric kidney compatible for AB0 system, HLA antigens (A19, B07, DR04), and negative results of cross-match test. The graft function was immediately restored, with normalization of creatinine levels achieved 4-5 days after surgery. Immunosuppression with cyclosporine, solumedrol, cellcept, metypred and simulect was performed in the hospital. Pulse therapy with solumedrol was performed on the day +20 due to the development of initial rejection signs. The postoperative period proceeded without infectious complications. The patient was discharged being recommended to take cyclosporine, Cell-Sept and Metypred. Within a year after transplantation, the patient claimed for pain in the hip joint, and, therefore, metypred was completely canceled. Subsequently, the Cellcept was replaced with a Mayfortic. In 2007, the signs of coxarthrosis were revealed at computed tomography, followed by aseptic necrosis of the the right femur head. Deforming osteoarthritis of the right hip joint was detected, and the hip replacement surgery was suggested. In 2010, due to risk of side effects from ongoing immunosuppressive therapy, e.g., joint damage, the Mayfortic was canceled. In 2012, being in fear of original Sandimmun Neoral replacement by a generic drug, the patient completely refused cyclosporine therapy. In 2021, the endoprosthetics of the right hip joint was performed, and the surgical wound healed initially. Since 2012, the patient has not completely taken immunosuppressive therapy. Over this time period, the patient has never been admitted to the hospital for impaired functioning of the organ graft. Meanwhile, he monitored his graft function on regular basis undergoing biochemical analyses, clinical examination, ultrasound studies of the graft and made regular visits to the outpatient department. In 2021, a week after hip replacement, there was a slight increase in serum creatinine, followed by further increase to 230 mmol/L in 2021, and to 310 mmol/L in March 2022. In February 2022, the patient suffered mild respiratory infection (confirmed COVID-19). In March 2022, the first clinical signs of increasing nephropathy appeared, i.e., swelling of both lower extremities, with leukocytes in urine upon routine analysis, increased blood flow resistance in the main artery of the transplant shown by ultrasound study. Due to worsening of the patient's condition, he resumed taking the prescribed immunosuppressants. Copyright © 2022, SPb RAACI.

EFFECT OF COVID-19 VACCINATION ON THE IMMUNE STATUS AND AUTOANTIBODY PROFILE IN WOMEN OF REPRODUCTIVE AGE.

In the context of the COVID-19 pandemic, scientific interest is growing in studying the impact of the proposed vaccination on women's reproductive health. As is known, alterations in the state of the immune system and activation of an autoimmune response can lead to reproductive failure in women and potential complications of subsequent pregnancy. Objective(s): to evaluate the effect of the "Gam-COVID-Vac" on the immune status parameters, the relationship of their changes and the specific immune response to vaccination with the dynamics of the level of autoantibodies in women of reproductive age. The prospective study included 120 women who were vaccinated against COVID-19 with the "Gam-COVID-Vac". The criteria for inclusion in the study were: the age from 18 to 49 years, the absence of COVID-19 in the anamnesis, a negative result of a study on SARS-CoV-2 by PCR and negative results of tests for antibodies of classes G and M to SARS-CoV-2 before vaccination, the absence of pregnancy and serious somatic diseases. The patients were examined twice: immediately before vaccination and 90-100 days after the introduction of the 1st component of the vaccine. The level of IgG antibodies to SARS-CoV-2 after vaccination was assessed using ELISA. Before and after vaccination, the levels of antiphospholipid, anti-nuclear, organ-specific and antihormonal autoantibodies were determined, peripheral blood lymphocytes were immunophenotyped to determine the main subpopulations (CD3, CD4, CD8, CD19, CD5, CD16, CD56), as well as the expression of activation markers of lymphocytes (HLA-DR, CD25, CD147) using monoclonal antibodies. The effectiveness and safety of the combined vector vaccine against COVID-19 were high. Specific IgG antibodies to SARS-CoV-2 were produced in 98.3% of vaccinated women, no serious adverse reactions were observed. After vaccination, there was an increase in the level of some autoantibodies within the reference ranges, only IgM antibodies to phosphatidylethanolamine (PE) and IgG antibodies to DNA increased above the reference values. However, this increase was transient. After vaccination, the following changes in the parameters of the immunogram were observed: an increase in the content of cells with CD3+CD25+, CD19+ phenotype in peripheral blood and a decrease in the content of cells with CD56+CD16+ phenotype within the reference ranges, a decrease in CD147+/CD3+. Weak correlations were noted between these changes in immunogram parameters and the levels of some autoantibodies. The specific antiviral immune response to vaccination did not correlate with the autoimmune response. Vaccination with "Gam-COVID-Vac" is effective and safe and does not lead to disorders in the immune system. The observed increase in the level of autoantibodies to PE and DNA is transient. Changes in the parameters of the immune status within the reference ranges may be due to vaccination and the development of a specific antiviral immune response. Copyright © 2022, SPb RAACI.

Monocytic HLA-DR Expression in Immune Responses of Acute Pancreatitis and COVID-19.

Acute pancreatitis is a common gastrointestinal disease with increasing incidence worldwide. COVID-19 is a potentially life-threatening contagious disease spread throughout the world, caused by severe acute respiratory syndrome coronavirus 2. More severe forms of both diseases exhibit commonalities with dysregulated immune responses resulting in amplified inflammation and susceptibility to infection. Human leucocyte antigen (HLA)-DR, expressed on antigen-presenting cells, acts as an indicator of immune function. Research advances have highlighted the predictive values of monocytic HLA-DR (mHLA-DR) expression for disease severity and infectious complications in both acute pancreatitis and COVID-19 patients. While the regulatory mechanism of altered mHLA-DR expression remains unclear, HLA-DR-/low monocytic myeloid-derived suppressor cells are potent drivers of immunosuppression and poor outcomes in these diseases. Future studies with mHLA-DR-guided enrollment or targeted immunotherapy are warranted in more severe cases of patients with acute pancreatitis and COVID-19.

EFFECT OF COVID-19 VACCINATION ON THE IMMUNE STATUS AND AUTOANTIBODY PROFILE IN WOMEN OF REPRODUCTIVE AGE

In the context of the COVID-19 pandemic, scientific interest is growing in studying the impact of the proposed vaccination on women's reproductive health. As is known, alterations in the state of the immune system and activation of an autoimmune response can lead to reproductive failure in women and potential complications of subsequent pregnancy. Objective: to evaluate the effect of the "Gam-COVID-Vac” on the immune status parameters, the relationship of their changes and the specific immune response to vaccination with the dynamics of the level of autoantibodies in women of reproductive age. The prospective study included 120 women who were vaccinated against COVID-19 with the "Gam-COVID-Vac”. The criteria for inclusion in the study were: the age from 18 to 49 years, the absence of COVID-19 in the anamnesis, a negative result of a study on SARS-CoV-2 by PCR and negative results of tests for antibodies of classes G and M to SARS-CoV-2 before vaccination, the absence of pregnancy and serious somatic diseases. The patients were examined twice: immediately before vaccination and 90-100 days after the introduction of the 1st component of the vaccine. The level of IgG antibodies to SARS-CoV-2 after vaccination was assessed using ELISA. Before and after vaccination, the levels of antiphospholipid, anti-nuclear, organ-specific and antihormonal autoantibodies were determined, peripheral blood lymphocytes were immunophenotyped to determine the main subpopulations (CD3, CD4, CD8, CD19, CD5, CD16, CD56), as well as the expression of activation markers of lymphocytes (HLA-DR, CD25, CD147) using monoclonal antibodies. The effectiveness and safety of the combined vector vaccine against COVID-19 were high. Specific IgG antibodies to SARS-CoV-2 were produced in 98.3% of vaccinated women, no serious adverse reactions were observed. After vaccination, there was an increase in the level of some autoantibodies within the reference ranges, only IgM antibodies to phosphatidylethanolamine (PE) and IgG antibodies to DNA increased above the reference values. However, this increase was transient. After vaccination, the following changes in the parameters of the immunogram were observed: an increase in the content of cells with CD3+CD25+, CD19+ phenotype in peripheral blood and a decrease in the content of cells with CD56+CD16+ phenotype within the reference ranges, a decrease in CD147+/CD3+. Weak correlations were noted between these changes in immunogram parameters and the levels of some autoantibodies. The specific antiviral immune response to vaccination did not correlate with the autoimmune response. Vaccination with "Gam-COVID-Vac” is effective and safe and does not lead to disorders in the immune system. The observed increase in the level of autoantibodies to PE and DNA is transient. Changes in the parameters of the immune status within the reference ranges may be due to vaccination and the development of a specific antiviral immune response. © 2022, SPb RAACI.

Perspectivas Inovadoras Na Abordagem Na Doenca Do Olho Seco (Dos) E O Interfaceamento Com Bancos De Sangue De Cordao Umbilical Humano

Os bancos de sangue de cordao umbilical e placentario (BSCUP), os laboratorios de processamento de medula ossea/ sangue periferico para transplante e os centros de tecnologia celular, passaram a receber a denominacao comum de Centros de Processamento Celular - CPC. O pais tem BSCUP 14 unidades publicas e 19 de natureza privada, totalizando 33 BSCUP. Uma analise retrospectiva dos relatorios da ANVISA identifica que em 2003 foram coletadas 26 unidades, com desqualificacao de 15,38% delas, o crescimento da coleta foi exponencial e dez anos depois, em 2013, foram coletadas 13.995 unidades (5,82% de desqualificacao). Em 2020, houve uma diminuicao expressiva de coletas, reflexo da pandemia de COVID-19: 4.918 unidades (desqualificacao de 12,69%). Este tipo de produtividade compromete a viabilidade financeira destes servicos, e encontrar formas de otimizar bolsas desqualificadas por volume ou quantidade de celulas para demais finalidades e uma vertente de gestao que deve ser estabelecida. O objetivo deste projeto foi a coleta de segmentos de cordao umbilical das unidades ja previamente validadas pelos BSCUP para extracao de celulas tronco, caracterizacao imunofenotipica e producao de meio condicionado isento de soro fetal bovino. A obtencao do meio condicionado (MC) da cultura de celulas tronco. Tem crescido cada vez mais o interesse pelo uso dos fatores de crescimento, citocinas e moleculas sinalizadoras livres no MC alem das vesiculas extracelulares, que se tornaram relevantes, tanto para diagnostico como para terapeutica, inclusive para aplicacoes oftalmologicas. Neste campo, identificamos a DOS que impacta profundamente a qualidade de vida das pessoas. Ha 15 anos o Laboratorio de Biologia Celular tem desenvolvido o soro autologo, para atendimento dos pacientes refratarios aos tratamentos convencionais e farmacologicos disponiveis, em especial aqueles pacientes submetidos ao Transplante de Medula Ossea e que desenvolveram DOS2ario a doenca de enxerto versus hospedeiro. No entanto, existem pacientes com impossibilidade de acesso venoso ou com sorologias reagentes para doencas infecciosas que sao impedidos de utilizar o produto. Diante disto, optou-se por produzir o MC de celulas tronco de cordao umbilical de parturientes jovens e sem comorbidades para obtencao do secretoma das celulas para avaliacao terapeutica na DOS. Um segmento do cordao umbilical foi retirado e processado seguido de plaqueamento e expansao para posterior identificacao de adesao ao plastico, caracterizacao imunofenotipica por citometria de fluxo utilizando marcadores como CD11b, CD13, CD14, CD34, CD31, CD36, CD45,CD73, CD90, CD 105, CD106 e HLA-DR. Todas as amostras tiveram adesao ao plastico com aspecto fibroblastoides e perfil imunofenpotipico corrobora com o determinado pela SITC. Para a obtencao de MC foram semeadas CTMcup ate 70% de confluencia e foram submetidas ao wash out, recebendo meio de cultura DMEM-F12 aditivado por 48 horas. Apos isto, foi coletado 60mL do secretoma das celulas para o experimento especificos in vitro. Copyright © 2022

Eficacia Do Tratamento Baseado Em Venetoclax Em Paciente Jovem Com Leucemia Mieloide Aguda Recidivada Candidato a Transplante De Medula Ossea Alogenico

Introducao: A Leucemia Mieloide Aguda (LMA) e uma doenca agressiva, e em geral, de prognostico reservado. O tratamento com intuito curativo e realizado com altas doses de quimioterapia, seguido ou nao por transplante de medula ossea (TMO) alogenico. Porem, a recidiva ainda representa um desafio a ser superado, levando a busca de novas opcoes terapeuticas, como o inibidor de bcl-2, Venetoclax. Objetivo: Relatar o caso de um paciente jovem com LMA recidivada com resposta ao tratamento baseado em Venetoclax, seguido por TMO alogenico. Metodo: Levantamento de dados do prontuario e revisao da literatura. Relato do caso: VSV, sexo masculino, 21 anos, diagnosticado com LMA em 18/02/2020, mielograma com 60,4% blastos, com fenotipo CD45+ intermediario;CD34+;CD13+;CD33 parcial;CD64 parcial;HLA-DR parcial;MPO parcial e cariotipo 46, XY [20]. Sem possibilidade de avaliacao molecular da doenca. O paciente recebeu tratamento de inducao padrao (D3A7) atingindo remissao completa apos um ciclo e seguindo com consolidacao com 3 ciclos de ARA-C 3g/m2 ate maio de 2020 (optou-se por nao realizar o 4ciclo devido a pandemia por COVID19). Apresentava doenca residual minima (DRM) negativa em reavaliacao medular de agosto de 2020, mantendo-se ate junho de 2021, quando apresentou recidiva com 33,8% de blastos em imunofenotipagem de reavaliacao. Internado em julho de 2021 para QT de resgate com FLAG, evoluiu com choque septico e insuficiencia respiratoria, sendo necessario suporte em unidade de terapia intensiva. Apos recuperacao clinica, obteve novamente DRM negativa, sendo encaminhado para TMO alogenico aparentado (irma "full match"). Entretanto, enquanto aguardava o transplante, apresentou nova recidiva (IF com 5,4% de blastos), sendo optado por tratamento com Venetoclax + Azacitidina, com reducao de DRM para 1,5%. Recebeu o segundo ciclo de Venetoclax combinado com citarabina, devido a indisponibilidade da Azacitidina, seguido por DRM negativa. O paciente foi submetido ao TMO alogenico em 31/03/22, com avaliacao medular no D+60 com quimerismo de 100%, mantendo DRM negativa no D+120. Discussao: O uso do inibidor de BCL-2 (Venetoclax), em combinacao com agentes hipometilantes ou doses baixas de citarabina, foi aprovado para pacientes recem-diagnosticados com LMA inelegiveis para quimioterapia intensiva, revolucionando o tratamento da doenca. Publicacoes recentes vem demonstrando novos beneficios dessa associacao, tanto previamente ao TMO (em primeira linha ou com doenca recidivada), como na terapia de resgate para recidiva pos-TMO. Tambem tendo sido evidenciado sucesso terapeutico em faixas etarias menores (incluindo criancas). Esses novos estudos motivaram o uso de terapia baseada em venetoclax nesse paciente jovem, com doenca recidivada, conseguindo atingir e manter DRM negativa. Conclusao: O caso relatado demonstra eficacia do Venetoclax (em combinacao com hipometilante ou citarabina) em promover remissao profunda da doenca, tornando o paciente habil para o transplante e aumentando a probabilidade de sobrevida a longo prazo. Copyright © 2022