Duration of antibody response to the receptor binding domain of SARS-CoV-2 in infected or vaccinated individuals - A one year retrospective cohort study.

The 2019 coronavirus (COVID-19) pandemic raised many scientific and medical questions. Of interest are the duration and effectiveness of the humoral immune response, especially since part of the pandemic occurred in the presence of anti-SARS-CoV-2 vaccines. We retrospectively studied 564 serum samples from 393 post-infected and vaccinated individuals to investigate the longevity and magnitude of the anti-spike IgG response. Our results showed that SARS-CoV-2 anti-spike IgG antibodies are retained for nine-twelve months, in both groups. In the vaccinated group we found higher IgG levels, but with a steeper decrease in titer over the study period. The recovered group's antibody levels correlated well with the national infection trendline for 2021. Both groups showed different, but distinct neutralizing capabilities towards RBD. The anti-Spike IgG response was sustained and efficient, independently of the triggering event, infection or vaccination, with the adaptive capacity against new viral variants being more valuable after infection.

Decreased ratio of FOXP3+/FOXP3-CD45RA+CD4+ T cells in peripheral blood is associated with unexplained infertility and ART failure.

Unexplained infertility has a huge social impact and is a significant challenge for both clinicians and researchers. Previous studies have shown the involvement of multiple factors in infertility. Among these, the subset of regulatory T cells is of particular interest for the maternal tolerance towards the semi-allogenic fetus. We investigated circulating CD45RA+ regulatory and non-regulatory CD4+ T cells in healthy women and patients with unexplained infertility in the context of thymic output and peripheral proliferation. The proportion of FOXP3+ and FOXP3-CD45RA+CD4+ T cells in peripheral blood was studied in control groups of healthy parous and nulliparous (never-pregnant) women and in patients with unexplained infertility. In the same groups thymic output and peripheral proliferation were defined by the sj/ßTREC ratio, and signal joint T-cell receptor excision circles (sjTREC) and Ki67 expression, respectively. In parous women a decrease in sjTREC/105 cells and CD45RA+ T lymphocytes, compared to nulliparous group was found. At the same time, the proportion of FOXP3-CD45RA+CD4+ cells, but not FOXP3+CD45RA+ Tregs was reduced. In contrast, in patients with unsuccessful pregnancy, proportions of both regulatory and non-regulatory T cell counterparts were lower. Taken together, our results provide evidence for group-specific properties in the CD45RA+ T cell compartment between healthy parous, nulliparous and women with unexplained infertility.

Late Postpregnancy Modifications in the Subset of Peripheral Natural T Regulatory Cells in Healthy Women.

The establishment of a relevant regulatory T cell (Treg) pool in the periphery is of importance to ensure immune homoeostasis. Finely tuned signaling pathways in Tregs control the immune response during extreme endocrine changes in pregnancy and afterward. In this study, we investigate the population of Tregs and, in particular, the natural Tregs (nTregs) in healthy women divided into three groups according to the number of previous pregnancies, if any (Gr.1-one pregnancy, Gr.2-≥2 pregnancies, and Gr.0-no pregnancy). The overall analysis showed similar proportions in the entire Treg pool and nTregs (FoxP3+CD45RA+) in all the three groups (p > 0.05). However, the age-related trend of CD25+ nTregs was found to be different in parous and nonparous women. Analysis of phosphorylated ERK1/2, an important signaling molecule in T cell maintenance, showed a significantly higher percentage in CD25+ nTregs in the group of nonparous compared with parous women (p < 0.05). Thus, our results provide evidence that pregnancy may exert a long-lasting impact on the subset of nTregs due to the extreme changes in the hormonal status, which in turn, influences pre- and post-thymic maturation.