IL-33 and Soluble ST2 Are Associated With Recurrent Spontaneous Abortion in Early Pregnancy

Normal pregnancy is related to the successful transition from type 1 cellular immunity to type 2 cellular immunity. Therefore, this study aimed to investigate whether there is abnormal expression of cytokines in the process of inducing Recurrent spontaneous abortion (RSA). Interleukin (IL)-33 is a new member of the IL-1 family, and ST2, as IL-33’s receptor, induced the production of type 2 cytokines. In this study, blood samples were collected from 19 non-pregnant women of normal childbearing age, 28 normal pregnant women, and 33 women with RSA. The serum concentrations of IL-33 and ST2 were detected by flow cytometry. Our results showed that the serum concentrations of IL-33 and ST2 in the RSA group were significantly higher than those in the healthy control group (IL-33: P < 0.05; ST2: P < 0.0001), and IL-33 and ST2 had a higher level in the process of RSA predictive value. In addition, this study initially found that the serum concentrations of IL-33 and ST2 were not significantly correlated with the number of weeks of pregnancy, and there was a lower correlation between IL-33 and ST2 during RSA. This result may be related to the small number of cases. This study is the first time to correlate the changes in serum concentrations of IL-33 and ST2 with RSA, which may be a novel biomarker for the prediction and treatment of RSA.

Successful outcome of pre-engraftment COVID-19 in an HCT patient: impact of targeted therapies and cellular immunity

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has emerged as a global pandemic that upended existing protocols and practices, including those for allogeneic hematopoietic stem cell transplantation (HCT). Here we describe the successful clinical course and multiple key interventions administered to an acute lymphoblastic leukemia patient, who tested SARS-CoV-2 positive by RT-PCR on day -1 of matched unrelated donor (SARS-CoV-2 IgG negative) T-cell-replete HCT. This experience allowed for implementing a virologic and immunomonitoring panel to characterize the impact of SARS-CoV-2 on the recipient's nascent humoral and cellular immune response. The finding of robust, functional, and persistent levels of SARS-CoV-2 specific T-cells, starting early after transplant was unexpected, and in combination with the clinical strategy may have contributed to the favorable outcome. Additionally, it is plausible that pre-existing cross-reactive endemic coronavirus immunity in the allogeneic graft reduced recipient susceptibility to COVID-19 disease. This case supports the critical role that T-cell responses may play in mitigating SARS-CoV-2 infection, even in the context of transplant immunosuppression, in which reconstitution of humoral response is commonly delayed. Interventional approaches to transfer SARS-CoV-2-specific cellular immunity such as HCT donor vaccination and adaptive cellular therapy could be of benefit.

Vaccines Elicit Highly Cross-Reactive Cellular Immunity to the SARS-CoV-2 Omicron Variant

The highly mutated SARS-CoV-2 Omicron (B.1.1.529) variant has been shown to evade a substantial fraction of neutralizing antibody responses elicited by current vaccines that encode the WA1/2020 Spike immunogen, resulting in increased breakthrough infections and reduced vaccine efficacy. Cellular immune responses, particularly CD8+ T cell responses, are likely critical for protection against severe SARS-CoV-2 disease. Here we show that cellular immunity induced by current SARS-CoV-2 vaccines is highly cross-reactive against the SARS-CoV-2 Omicron variant. Individuals who received Ad26.COV2.S or BNT162b2 vaccines demonstrated durable CD8+ and CD4+ T cell responses that showed extensive cross-reactivity against both the Delta and Omicron variants, including in central and effector memory cellular subpopulations. Median Omicron-specific CD8+ T cell responses were 82-84% of WA1/2020-specific CD8+ T cell responses. These data suggest that current vaccines may provide considerable protection against severe disease with the SARS-CoV-2 Omicron variant despite the substantial reduction of neutralizing antibody responses.

Long-lasting cellular immunity to SARS-CoV-2 following infection or vaccination and implications for booster strategies

Immunization against SARS-CoV-2, the causative agent of coronavirus disease-19 (COVID-19) occurs via natural infection or vaccination. However, it is currently unknown how long infection- or vaccination-induced immunological memory will last. We performed a longitudinal evaluation of immunological memory to SARS-CoV-2 following mRNA vaccination in naïve and COVID-19 recovered individuals. We found that cellular immunity is still detectable 8 months after vaccination, while antibody levels decline significantly especially in naïve subjects. We also found that a booster injection is more efficacious in reactivating immunological memory to spike protein in naïve than in previously SARS-CoV-2 infected subjects. Finally, we observed a similar kinetics of decay of humoral and cellular immunity to SARS-CoV-2 up to one year following natural infection in a cohort of unvaccinated individuals. Short-term persistence of humoral immunity may account for reinfections and breakthrough infections, although long-lived memory B and CD4+ T cells may protect from severe disease. A booster dose restores optimal anti-spike immunity in naïve subjects, while the need for vaccinated COVID-19 recovered subjects has yet to be defined.

Children develop robust and sustained cross-reactive spike-specific immune responses to SARS-CoV-2 infection

SARS-CoV-2 infection is generally mild or asymptomatic in children but a biological basis for this outcome is unclear. Here we compare antibody and cellular immunity in children (aged 3–11 years) and adults. Antibody responses against spike protein were high in children and seroconversion boosted responses against seasonal Beta-coronaviruses through cross-recognition of the S2 domain. Neutralization of viral variants was comparable between children and adults. Spike-specific T cell responses were more than twice as high in children and were also detected in many seronegative children, indicating pre-existing cross-reactive responses to seasonal coronaviruses. Importantly, children retained antibody and cellular responses 6 months after infection, whereas relative waning occurred in adults. Spike-specific responses were also broadly stable beyond 12 months. Therefore, children generate robust, cross-reactive and sustained immune responses to SARS-CoV-2 with focused specificity for the spike protein. These findings provide insight into the relative clinical protection that occurs in most children and might help to guide the design of pediatric vaccination regimens.

Role of the cellular immunity in the formation of the immune response in coronavirus infections

The data obtained during previous epidemics caused by coronaviruses, and current pandemic indicate that assessing the role of certain immune interactions between these viruses and the microorganism is the main pre-requisite for development of diagnostic test systems as well as effective medical drugs and preventive measures. The review summarizes the results of studying patho– and immunogenesis of SARSCoV, MERS-CoV, and SARS-CoV-2 infections. These coronaviruses were proven to suppress development of adaptive immune response at the stage of its induction, affecting the number and functional activity of lymphocytes, effectors of cellular immunity, causing impairment of lymphopoiesis, apoptosis and «depletion» of these cells, thus leading to longer duration of the disease and increased viral load. Information about the role of cellular immunity in development of immune response to coronaviruses is presented. It was proven that the causative agents of SARS, MERS and COVID-19 trigger adaptive immune response in the microorganism according to both humoral and cellular types. Moreover, the synthesis of specific immunoglobulins does not yet point to presence of protective immune response. Activation of the cellular link of immunity is also important. A high degree of antigenic epitope homology in SARS-CoV, MERS-CoV and SARS-CoV-2 is described, thus suggesting an opportunity for cross-immunity to coronaviruses. The review addresses issues related to the terms of specific memory immune cells to SARS-CoV, MERS-CoV and SARS-CoV-2, and their role in providing long-term protection against these infections. Given that specific antibodies to SARS and MERS pathogens persisted for a year, were often not detected or briefly registered in patients with mild and asymptomatic infections, we can talk about important role of the cellular immune response in providing immunity to these coronaviruses. It was shown that, in contrast to antibodies, the antigen-specific memory T cells were registered in patients with SARS virus for 4 to 11 years, and Middle East Respiratory Syndrome – up to two years. Further research is needed to determine presence and number of memory T cells in COVID-19. A comparative analysis of data obtained during previous epidemics with respect to formation of adaptive immunity to coronaviruses. Description of proteins and epitopes recognized by human T lymphocytes will be useful in monitoring immune responses in COVID-19 patients, as well as in developing informative tests to study T cell immune response to SARS-CoV-2 and new preventive drugs.

Anti-SARS-CoV-2 cellular immunity in 571 vaccinees assessed using an interferon-γ release assay

Generation of antigen-specific memory T cells has been analyzed only for few coronavirus disease 2019 (COVID-19) vaccinees, whereas antibody titers have been serologically measured for a large number of individuals. Here, we assessed the anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cellular immune response in a large cohort using interferon (IFN)-γ release assays (IGRAs) based on short-term whole blood culture. The study included 571 individuals who received the viral spike (S) protein-expressing BNT162b2 mRNA SARS-CoV-2 vaccine. Serum IgG titers against the receptor-binding domain (RBD) of S protein were measured. Samples of 28 vaccinees were subjected to flow cytometry analysis of T cells derived from short-term whole blood culture. IFN-γ production triggered by S antigens was observed in most individuals 8 weeks after receiving the second dose of the vaccine, indicating acquisition of T cell memory responses. The frequencies of activated T cell subsets were strongly correlated with IFN-γ levels, supporting the usability of our approach. S antigen-stimulated IFN-γ levels were weakly correlated with anti-RBD IgG titers and associated with pre-vaccination infection and adverse reactions after the second dose. Our approach revealed cellular immunity acquired after COVID-19 vaccination, providing insights regarding the effects and adverse reactions of vaccination.