Evaluation of hematological parameters and inflammatory markers in children with COVID-19.

BACKGROUND: The aim of this study was to evaluate hematological parameters in children with COVID-19 and determine the effects of inflammatory biomarkers on the assessment of hospitalization. METHODS: This retrospective single-center study was performed on 633 children with COVID-19 between March 2020 and January 2021. The study population was separated into two groups: inpatients (n = 83) and outpatients (n = 550). Univariate and multivariate logistic regression was applied to identify risk factors for hospitalization. RESULTS: Lymphopenia (n = 228, 36%) was found mainly to be a hematological abnormality in all cases. Compared with outpatients, inpatients had significantly higher white blood cell (WBC) (p = 0.005), lymphocyte (p < 0.001), and platelet counts (p = 0.036), and significantly higher red cell distribution width (p = 0.001), C-reactive protein (CRP) (p = 0.003), procalcitonin (p = 0.001), D-dimer (p < 0.001), and lymphocyte to monocyte ratio values (p = 0.004). On the other hand, they had significantly lower values of hemoglobin (p < 0.001), neutrophil to lymphocyte ratio (p = 0.024), platelet lymphocyte ratio (p = 0.001), derivated neutrophil to lymphocyte ratio (p = 0.037), and mean platelet volume to lymphocyte ratio (p < 0.001). ROC analysis showed that WBC, CRP, and procalcitonin cutoff values were the best discriminated between inpatients and outpatients. The results for the areas under the curve of WBC, CRP, and procalcitonin used to assess patients' hospitalization were 0.595 (95% CI 0.519-0.670, p = 0.005), 0.599 (95% CI 0.527-0.672, p = 0.003), and 0.599 (95% CI 0.525-0.673, p = 0.004), respectively. CONCLUSION: We suggest that high WBC and procalcitonin levels can be used as independent predictors of hospitalization in children with COVID-19.

The role of CD8+ regulatory T cells and B cell subsets in patients with COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has a wide clinical spectrum from asymptomatic to mild, moderate, and severe cases. There are still many unknowns about the role of immunoregulatory mechanisms in COVID-19. We aimed to study regulatory T cells (Tregs) and B cell subsets and evaluate their correlations with severity of COVID-19. METHODS: In total, 50 patients with COVID-19 confirmed by PCR (mean age = 49.9 ± 12.8 years) and 40 healthy control (mean age = 47.9 ± 14.7 years) were included in this study. The patients were classified as 14 mild (median age = 35.5 [24-73] years), 22 moderate (median age = 51.5 [28-67] years) and 14 severe (median age = 55.5 [42-67] years). Within 24 h of admission, flow cytometry was used to assess the lymphocyte subsets, Tregs and Bregs without receiving any relevant medication. RESULTS: In all patients with COVID-19, the proportion of CD3+CD8+ T cells was reduced (p = 0.004) and the CD8+ Tregs were increased compared with control (p = 0.001). While the levels of regulatory B cells, plasmablasts, and mature naive B cells were found to be significantly high, primarily memory B-cell levels were low in all patients compared with controls (p < 0.05). Total CD3+ T cells were negatively correlated with the length of stay in the hospital (r = -0.286, p = 0.044). DISCUSSION: The changes in T and B cell subsets may show the dysregulation in the immunity of patients with COVID-19. In this context, the association between CD8+ Tregs and COVID-19 severity may help clinicians to predict severe and fatal COVID-19 in hospitalized patients.

Correlation of myeloid-derived suppressor cells with C-reactive protein, ferritin and lactate dehydrogenase levels in patients with severe COVID-19.

The novel coronavirus disease 2019 (COVID-19) remains a global health emergency, and understanding the interactions between the virus and host immune responses is crucial to preventing its lethal effects. The expansion of myeloid-derived suppressor cells (MDSCs) in COVID-19, thereby suppressing immune responses, has been described as responsible for the severity of the disease, but the correlation between MDSC subsets and COVID-19 severity remains elusive. Therefore, we classified patients according to clinical and laboratory findings-aiming to investigate the relationship between MDSC subsets and laboratory findings such as high C-reactive protein, ferritin and lactate dehydrogenase levels, which indicate the severity of the disease. Forty-one patients with COVID-19 (26 mild and 15 severe; mean age of 49.7 ± 15 years) and 26 healthy controls were included in this study. MDSCs were grouped into two major subsets-polymorphonuclear MDSCs (PMN-MDSCs) and monocytic MDSCs-by flow cytometric immunophenotyping, and PMN-MDSCs were defined as mature and immature, according to CD16 expressions, for the first time in COVID-19. Total MDSCs, PMN-MDSCs, mature PMN-MDSCs and monocytic MDSCs were significantly higher in patients with COVID-19 compared with the healthy controls (P < .05). Only PMN-MDSCs and their immature PMN-MDSC subsets were higher in the severe subgroup than in the mild subgroup. In addition, a significant correlation was found between C-reactive protein, ferritin and lactate dehydrogenase levels and MDSCs in patients with COVID-19. These findings suggest that MDSCs play a role in the pathogenesis of COVID-19, while PMN-MDSCs, especially immature PMN-MDSCs, are associated with the severity of the disease.

The Relationship between COVID-19 Severity and Bacillus Calmette-Guérin (BCG)/ Mycobacterium tuberculosis exposure history in healthcare workers: a multi-center study.

The COVID-19 pandemic has brought countries' health services into sharp focus. It was drawn to our group's attention that healthcare workers (HCWs) had a lower mortality rate against higher COVID-19 incidence compared to the general population in Turkey. Since risk of exposure to tuberculosis bacillus among healthcare workers are higher than the population, we aimed to investigate if there is a relationship between BCG and Mycobacterium tuberculosis exposure history with COVID-19 severity in infected HCWs. This study was conducted with 465 infected HCWs from thirty-three hospitals to assess the relationship between COVID-19 severity (according to their hospitalization status and the presence of radiological pneumonia) and BCG and Mycobacterium tuberculosis exposure history. HCWs who required hospital admission had significantly higher rates of chronic diseases, radiological pneumonia, and longer working hours in the clinics. Higher rates of history of contact and care to tuberculosis patients, history of tuberculosis, and BCG vaccine were observed in hospitalized HCWs. HCWs who had radiological pneumonia had a significantly increased ratio of history of care to tuberculosis patients and a higher family history of tuberculosis. The findings from our study suggest that the lower mortality rate despite the more severe disease course seen in infected HCWs might be due to frequent exposure to tuberculosis bacillus and the mortality-reducing effects of the BCG vaccine.