Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and its mechanisms have been thoroughly studied by researchers all over the world with the hope of finding answers that may aid the discovery of new treatment options or effective means of prevention. Still, over 2 years into the pandemic that is an immense burden on health care and economic systems, there seem to be more questions than answers. The character and multitude of immune responses elicited in coronavirus disease 2019 (COVID-19) vary from uncontrollable activation of the inflammatory system, causing extensive tissue damage and consequently leading to severe or even fatal disease, to mild or asymptomatic infections in the majority of patients, resulting in the unpredictability of the current pandemic. The aim of the study was to systematize the available data regarding the immune response to SARS-CoV-2, to provide some clarification among the abundance of the knowledge available. The review contains concise and current information on the most significant immune reactions to COVID-19, including components of both innate and adaptive immunity, with an additional focus on utilizing humoral and cellular responses as effective diagnostic tools. Moreover, the authors discussed the present state of knowledge on SARS-CoV-2 vaccines and their efficacy in cases of immunodeficiency.

Raynaud phenomenon (RP) may be the first manifestation of a systemic connective tissue disease (SCTD). Early detection of dysfunction of small vessels called microangiopathy is essential for the diagnostic process. The focus of this single-center, retrospective study was to investigate the potential dependencies between microvascular image and laboratory markers measured in children with RP. The study analyzed the nail-fold video-capillaroscopy (NVC) findings and laboratory results of 81 children between the ages 6 and 17 who were referred to pediatric rheumatologist with a suspicion of SCTD. Out of 52 patients presenting with RP at the time of evaluation, abnormalities in capillary microscopic imaging were found in 34. NVC findings were then compared to levels of specific biomarkers in serum. Vitamin D3 serum levels have been significantly decreased in patients with RP (23.4 ng/mL ± 8.76 vs. 30.0 ng/mL ± 12.66, P = 0.0148). There were positive significant correlations between levels of vitamin D3 and acute-phase reactants in serum, such as C-reactive protein ( P = 0.0292). Furthermore, free thyroxine levels (fT4) in patients with both RP ( P = 0.0126) and micro-angiopathy ( P = 0.05496) persisted in the lower range of the normal limit (< 1.0 ng/dL). Regular oral supplementation of vitamin D3 should be always considered in children with RP if deficiency is found. Additionally, low fT4 level (< 1.0 ng/dL) should be considered as an indication to perform NVC in patients suspected of SCTD even when they do not present RP.

BackgroundWhile serological assays detecting antibodies in blood serum remain the standard exam for evaluating immunity against SARS-CoV-2 infection, the latest publications reveal certain limitations to this broadly used method. Recent studies showing the decline of antibodies titers in time, together with scientific reports which detect SARS-CoV-2-specific T-cells in seronegative individuals, evoke questions with regard to the reliability of the sole assessment of the humoral response to SARS-CoV-2. A novel T-cell-based Interferon-γ Release Assay (IGRA) is proposed to adapt our approach to the individual immunity to the new coronavirus.ObjectivesThe objectives of this study were to assess T-cells and antibodies responses to the SARS-CoV-2 virus among pediatric patients at different stages of juvenile idiopathic arthritis (JIA) undergoing diverse treatment regimes. In addition, the authors aimed to evaluate humoral and cellular responses to the Covid-19 mRNA vaccine in the cohort of immunocompromised patients.MethodsThis prospective study included 30 pediatric patients between the ages 2-16 at different stages of JIA. The cohort group consisted of vaccinated and unvaccinated individuals and children with both positive and negative history of past Covid-19 infection. SARS-CoV-2 T-cell response was measured using a specific quantitative IGRA in whole blood, followed by anti-SARS-CoV-2 ELISA test measuring the presence and quantity of IgG, IgM and IgA antibodies in serum.ResultsThe magnitude of the SARS-CoV-2 specific T-cell response measured by the IGRA test correlated significantly with the levels of IgG (p<0.00005, R=0.653) and IgA antibodies (p<0.00001, R=0.675) in serum, while no correlation with IgM antibodies level in serum was found. All vaccinated patients developed a cellular response to the vaccine (p=0.0108), regardless of the number of administered doses. The T-cells response in children undergoing biological treatment (specifically: etanercept, adalimumab or tocilizumab) was recognizably weaker compared to the group not receiving such treatment. Nevertheless, the difference did not reach statistical significance (p=0.0715). Similar dependencies were found in children treated with hydroxychloroquine (n=6), however, due to the small study group, a statistical significance could not have been reached.ConclusionSuppression of cellular response observed in different drug protocols may prove to become a protective factor against SARS-CoV-2 infection. Additionally, the authors postulate that the strong correlation found between T-cell response and IgA antibodies titer can be related to SARS-CoV-2 strong affinity with mucosal membranes. Thus, the sole testing of IgG and IgM antibodies levels in serum with regard to Covid-19 may not be the most precise diagnostic method. The presented study group needs to be expanded with more patients, mainly children receiving biological agents or hydroxychloroquine to validate the demonstrated preliminary results.References[1]Prendecki M, Clarke C, Edwards H et al. Humoral and T-cell responses to SARS-CoV-2 vaccination in patients receiving immunosuppression. Ann Rheum Dis. 2021 Oct;80(10):1322-1329. doi: 10.1136/annrheumdis-2021-220626.Disclosure of InterestsNone declared