T-Cell Immunity in COVID-19-Recovered Individuals and Individuals Vaccinated with the Combined Vector Vaccine Gam-COVID-Vac.

The COVID-19 pandemic has required extensive research on the new coronavirus SARS-CoV-2 and the creation of new highly effective vaccines. The presence of T-cells in the body that respond to virus antigens suggests adequate antiviral immunity. We investigated T-cell immunity in individuals who recovered from mild and moderate COVID-19 and in individuals vaccinated with the Gam-COVID-Vac combined vector vaccine. The ELISPOT method was used to determine the number of T-cells responding with IFN-γ synthesis to stimulation by peptides containing epitopes of the S-protein or N-, M-, ORF3, and ORF7 proteins, using peripheral blood mononuclear cells (PBMCs). At the same time, the multiplex method was used to determine the accumulation of IFN-γ and other cytokines in the culture medium. According to the data obtained, the proportion of positive conclusions about the T-cell immune response to SARS-CoV-2 antigens in control, recovered, and vaccinated individuals was 12%, 70%, and 52%, respectively. At the same time, more than half of the vaccinated individuals with a T-cell response were sensitized to the antigens of N-, M-, ORF3, and ORF7 proteins not produced by Gam-COVID-Vac, indicating a high likelihood of asymptomatic SARS-CoV-2 infection. Increased IFN-γ release by single sensitized T-cells in response to specific stimulation in recovered and vaccinated individuals did not result in the accumulation of this and other cytokines in the culture medium. These findings suggest a balance between cytokine production and utilization by immunocompetent cells as a prerequisite for providing a controlled cytokine signal and avoiding a "cytokine storm".

Comparison of cord blood lactate measurement by gas analyzer and portable electrochemical devices.

Objective To compare the accuracy of cord blood lactate measurement using gas analyzer and portable devices in order to assess possibility of implementation of these devices in clinical practice. Methods We performed a prospective observational study using 30 umbilical cord samples which were obtained immediately after birth. Portable electrochemical devices Lactate Scout (SensLab GmbH, Leipzig, Germany) and StatStrip Lactate (NOVA Biomedical, Waltham, MA, USA) were used to determine lactate level. A gas analyzer ABL800 FLEX (Radiometer Medical ApS, Brønshøj-Husum, Denmark) was used as a reference. Base excess (BE), pH, partial oxygen (pO2) and carbon dioxide (pCO2) pressure, hemoglobin (ctHb) and bilirubin (ctBl) levels were measured. Results The mean umbilical cord blood lactate level determined by the gas analyzer was 5.85 ± 2.66 mmol/L (ranging from 1.4 mmol/L to 13.4 mmol/L). Lactate level estimated by Lactate Scout was 5.66 ± 2.65 mmol/L and did not significantly differ from the reference method level (P = 0.2547). The mean lactate level determined by StatStrip Lactate was significantly lower than by the gas analyzer - 4.81 ± 2.38 mmol/L (P < 0.0001). Umbilical cord blood pH, BE, pO2 and pCO2, ctHb and ctBl levels did not affect the accuracy of the lactate measurement in absolute units (mmol/L). Conclusion Umbilical cord blood lactate level measured by StatStrip Lactate was lower than estimated by the ABL800 FLEX gas analyzer. This shows the necessity to develop decision-making reference points separately for each device. Umbilical cord blood pH, BE, pO2 and pCO2, ctHb and ctBl levels did not affect the accuracy of measurements by electrochemical portable devices.

The role of abnormal hypermethylation of the HOXA10 and HOXA11 promoters in implantation failures in IVF programs.

Objective: The objective of this study is to investigate the association between methylation levels of HOXA10 and HOXA11 promoters, clinical parameters, and implantation outcomes after in vitro fertilization-embryo transfer (IVT-ET) cycles in women with repeated implantation failures and tubal infertility. Methods: Endometrium samples were collected from 34 women during implantation window before IVF-ET cycle to assess methylation status of HOXA10 and HOXA11 promoters using bisulfite sequencing. All participants had a tubal factor of infertility and at least two implantation failures in the anamnesis. A logistic regression model was used to predict the implantation outcome depending on methylation status and clinical parameters. Results: The methylation of CpG-islands of HOXA10 and HOXA11 promoters was identified in 76.5 and 100% of participants, respectively. The median methylation levels did not differ significantly between the groups with different implantation outcomes, but a logistic regression model based on HOXA10 and HOXA11 methylation and clinical parameters allowed to classify the implantation outcomes with the total percentage of correct predictions of 85.19%. Conclusions: Abnormal methylation levels of the HOXA10 and HOXA11 promoters were found in the endometrium of women with tubal infertility and repeated implantation failures. The findings suggest that methylation status could be an important factor of implantation failure during IVF-ET cycles.