We evaluated the antibody responses in 259 potential convalescent plasma donors for Covid-19 patients. Different assays were used: a commercial ELISA detecting antibodies against the recombinant spike protein (S1); a multiplex assay detecting total and specific antibody isotypes against three SARS-CoV-2 antigens (S1, basic nucleocapsid (N) protein and receptor-binding domain (RBD)); and an in-house ELISA detecting antibodies to complete spike, RBD and N in 60 of these donors. Neutralizing antibodies (NAb) were also evaluated in these 60 donors. Analyzed samples were collected at a median time of 62 (14–104) days from the day of first symptoms or positive PCR (for asymptomatic patients). Anti-SARS-CoV-2 antibodies were detected in 88% and 87.8% of donors using the ELISA and the multiplex assay, respectively. The multivariate analysis showed that age ≥50 years (p < 0.001) and need for hospitalization (p < 0.001) correlated with higher antibody titers, while asymptomatic status (p < 0.001) and testing >60 days after symptom onset (p = 0.001) correlated with lower titers. Interestingly, pseudotype virus-neutralizing antibodies (PsNAbs) significantly correlated with spike and with RBD antibodies by ELISA. Sera with high PsNAb also showed a strong ability to neutralize active SARS-CoV-2 virus, with hospitalized patients showing higher titers. Therefore, convalescent plasma donors can be selected based on the presence of high RBD antibody titers.

Graphical SARS-CoV-2 infection has significant effects on red blood cells that seems to be associated with disease severity in these patients.(A)Non-Intensive care unit hospitalized patients due to severe COVID-19 disease were included in this study (n= 36).(B)The control group included healthy subjects without renal or hepatic impairment, no diagnosis of anemia or myeloid malignancy, and no blood transfusion over the past 3 months (n= 18).(C)Demographic data, clinical, laboratory and chest Computed Tomography (CT) findings at time of admission were recorded. Hematological tests, standard biochemical analysis of serum components were performed both in the patient and in the control group and coagulation analysis were evaluated in the patient group. A peripheral blood smear examination was also performed in all patients and control samples.(D)Plasma free hemoglobin and red blood cell (RBC) osmotic fragility and free hemoglobin (Free-Hb) after mechanical stress (MECH) by mechanical hemolysis were assesed in both patients and controls. Intracellular (i) calcium (iCa2 +) levels, RBCs phosphatidylserine exposure (PS), RBC membrane-bound immunoglobulins G (IgGs), and activate RBC caspase-3 levels as cell clearance and apoptotic markers were measured by flow cytometry. A spectrophotometric assay was used to quantify the activity of G6PD enzyme. Intracellular RBC reactive oxidative species (iROS) were assesed in both patients and controls.(E)Elevated hemolysis markers (Free-Hb) and Lactate Dehydrogenase (LDH) were observed in patients compared to the control group. Patients’ RBCs were more vulnerable to mechanical stress, and exhibited significantly elevated apoptotic markers (iCa2 + and RBC-PS+). Erythrocyte iROS levels were significantly lower in the patients’ group compared to healthy controls. This finding possibly correlates with the increased G6PDH activity levels in this group, suggesting a compensatory mechanism against the virus.(F)Patients’ D-Dimers correlated with RBC-PS +, implying a possible contribution of the erythrocytes in the thrombotic diathesis associated with the SARS-CoV-2 disease.(G)Free-Hb levels correlated with the extend of pulmonary infiltrates on chest CT in COVID-19 patients. RBC-IgGs+ correlated with the severity of pulmonary CT imaging features as well as the abnormality of lung function, expressed by the PO2/FiO 2 ratio. This finding suggests that hypoxia may lead to RBC senescence.

The term epigenetics refers to the heritable changes in gene expression that do not represent changes in DNA sequence. DNA methylation and histone modification are the best studied epigenetic mechanisms. However, microRNAs, which affect gene expression at the posttranscriptional level, should be considered as members of the epigenetic machinery too. Myelodysplastic syndromes (MDS) are clone disorders of the hematopoietic stem cell with increased risk of leukemic transformation. Over the years, increased number of studies indicates the role of epigenetic mechanisms, including microRNAs, in MDS pathogenesis and prognosis. Indeed, epigenetic therapy with demethylating agents has already been applied to MDS. In this review we summarize current knowledge on the role of epigenetic alterations in MDS pathogenesis and treatment.