Detection of specific RBD+ IgG+ memory B cells by flow cytometry in healthcare workers and patients with inborn errors of immunity after BNT162b2 m RNA COVID-19 vaccination.

Introduction: Inborn errors of immunity (IEI) are a heterogeneous group of diseases caused by intrinsic defects of the immune system. Estimating the immune competence of immunocompromised patients for an infection risk assessment or after SARS-CoV-2 vaccination constituted a challenge. Methods: The aim of this study was to determine the humoral responses of patients with IEI through a comprehensive analysis of specific receptor-binding domain-positive (RBD+) IgG+ memory B cells (MBCs) by flow cytometry, together with routine S-specific IgG antibodies and QuantiFERON SARS-CoV-2 (T-cell response), before the vaccine and 3 weeks after a second dose. Results and discussion: We first analyzed the percentage of specific RBD+ IgG+ MBCs in healthy healthcare workers. Within the control group, there was an increase in the percentage of specific IgG+ RBD+ MBCs 21 days after the second dose, which was consistent with S-specific IgG antibodies.Thirty-one patients with IEI were included for the pre- and post-vaccination study; IgG+ RBD+ MBCs were not evaluated in 6 patients due to an absence of B cells in peripheral blood. We detected various patterns among the patients with IEI with circulating B cells (25, 81%): an adequate humoral response was observed in 12/25, consider by the detection of positive S-specific IgG antibodies and the presence of specific IgG+ RBD+ MBCs, presenting a positive T-cell response; in 4/25, very low S-specific IgG antibody counts correlated with undetectable events in the IgG+ RBD+ MBC compartment but with positive cellular response. Despite the presence of S-specific IgG antibodies, we were unable to detect a relevant percentage of IgG+ RBD+ MBCs in 5/25; however, all presented positive T-cell response. Lastly, we observed a profound failure of B and T-cell response in 3 (10%) patients with IEI, with no assessment of S-specific IgG antibodies, IgG+ RBD+ MBCs, and negative cellular response. The identification of specific IgG+ RBD+ MBCs by flow cytometry provides information on different humoral immune response outcomes in patients with IEI and aids the assessment of immune competence status after SARS-CoV-2 mRNA vaccine (BNT162b2), together with S-specific IgG antibodies and T-cell responses.

Epigenetic profiling linked to multisystem inflammatory syndrome in children (MIS-C): A multicenter, retrospective study.

Background: Most children and adolescents infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain asymptomatic or develop a mild coronavirus disease 2019 (COVID-19) that usually does not require medical intervention. However, a small proportion of pediatric patients develop a severe clinical condition, multisystem inflammatory syndrome in children (MIS-C). The involvement of epigenetics in the control of the immune response and viral activity prompted us to carry out an epigenomic study to uncover target loci regulated by DNA methylation that could be altered upon the appearance of MIS-C. Methods: Peripheral blood samples were recruited from 43 confirmed MIS-C patients. 69 non-COVID-19 pediatric samples and 15 COVID-19 pediatric samples without MIS-C were used as controls. The cases in the two groups were mixed and divided into discovery (MIS-C = 29 and non-MIS-C = 56) and validation (MIS-C = 14 and non-MIS-C = 28) cohorts, and balanced for age, gender and ethnic background. We interrogated 850,000 CpG sites of the human genome for DNA methylation variants. Findings: The DNA methylation content of 33 CpG loci was linked with the presence of MIS-C. Of these sites, 18 (54.5%) were located in described genes. The top candidate gene was the immune T-cell mediator ZEB2; and others highly ranked candidates included the regulator of natural killer cell functional competence SH2D1B; VWA8, which contains a domain of the Von Willebrand factor A involved in the pediatric hemostasis disease; and human leukocyte antigen complex member HLA-DRB1; in addition to pro-inflammatory genes such as CUL2 and AIM2. The identified loci were used to construct a DNA methylation profile (EPIMISC) that was associated with MIS-C in both cohorts. The EPIMISC signature was also overrepresented in Kawasaki disease patients, a childhood pathology with a possible viral trigger, that shares many of the clinical features of MIS-C. Interpretation: We have characterized DNA methylation loci that are associated with MIS-C diagnosis. The identified genes are likely contributors to the characteristic exaggerated host inflammatory response observed in these patients. The described epigenetic signature could also provide new targets for more specific therapies for the disorder. Funding: Unstoppable campaign of Josep Carreras Leukaemia Foundation, Fundació La Marató de TV3, Cellex Foundation and CERCA Programme/Generalitat de Catalunya.

Humoral and cellular immune responses to Pfizer-BioNTech BNT162b2 SARS-CoV-2 vaccine in adolescents with liver transplantation: Single center experience

Background Immune responses to vaccines against severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 are variable. In the absence of disease, youngsters are expected to better react to vaccines than adults. Nevertheless, chronic immunosuppression in transplant recipients may impair their capability to generate protection. We aim to explore immune responses after BNT162b2 SARS-CoV-2 vaccination in our cohort of young liver-transplanted patients. Methods A prospective study of adolescent liver-transplanted patients (n=33) in the long-term follow-up was performed. Immune responses after receiving Pfizer-BioNTech BNT162b2 vaccine were analyzed at two time-points: baseline and 30 days after the second dose. Humoral responses were measured by fluoroenzyme-immunoassay and T-cell responses by interferon-γ-release assay. Post-vaccine coronavirus disease (COVID-19) events were recorded by a survey. Results Pre-vaccine SARS-CoV-2-specific antibodies were undetectable in 27/32 (84.4%), negative/indeterminate in 3/32 (9.4%) and positive in 2/32 (6.3%) patients. Cellular responses at baseline were negative in 12/18 (66.6%), positive in 3/18 (16.6%) and indeterminate in 3/18 (16.6%) recipients. None of the baseline positives recalled any symptoms. Post-vaccine antibodies were detected in all patients and 92.6% showed levels >816 BAU/mL. Twenty (71.4%) recipients had positive T-cell responses. Regarding post-vaccine SARS-Cov-2 infection, 10 (30.3%) patients reported COVID-19 without hospitalization and 21 (63.6%) did not notify any infection. Negative and positive cell-response groups after vaccination showed statistically significant differences regarding COVID-19 cases (62.5% vs 22.2%, respectively;p=0.046). Conclusions Adolescents and young adults with liver transplantation responded to SARS-Cov-2 vaccine, generating both humoral and cellular responses. Recipients developing cellular responses after vaccination had a lower incidence of COVID-19.

Cytokine Profile in Children with Severe Multisystem Inflammatory Syndrome Related to the Coronavirus Disease 2019

The multisystem inflammatory syndrome in children (MIS-C) is a novel and concerning entity related to severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection. Although MIS-C has been the subject of intensive research efforts, its pathophysiology and optimal treatment remain elusive. We studied the clinical features, laboratory findings, and immunoinflammatory profiles of seven children prospectively admitted to a pediatric intensive care unit (PICU) during the first wave of the pandemic. All patients had immunoglobulin (Ig)-G against SARS-CoV-2, four of seven patients had both IgM and IgG, and in one of the 7 SARS-CoV-2 was detected in a respiratory sample. All patients received intravenous fluid boluses (median: 15 mL/kg) and norepinephrine. The most common form of respiratory support was supplemental oxygen via nasal cannula. None of the patients needed mechanical ventilation. The cardiovascular system was frequently involved. All patients had an elevated troponin-I (median: 107.3 ng/L). Four out of seven patients had coronary artery abnormalities, and two of seven had both abnormal electrocardiogram (EKG) findings and evidence of left ventricular dysfunction on echocardiogram. Ig levels and complement function were normal. Peripheral blood phenotyping with flow cytometry showed decreased T-cell numbers at the expense of CD8+ T-cells. Cytokine profiling showed a heterogeneous increase in interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-18, IL-2Ra, IL-10, and IL-1Ra that tended to normalize after treatment. Our study shows that children with MIS-C have elevated plasma levels of pro- and anti-inflammatory cytokines in the acute phase of the disease without other relevant immunologic disturbances. These findings suggest the presence of a mixed antagonist response syndrome (MARS) similar to that present in pediatric sepsis. Combining a meticulous differential diagnosis with cautiously coordinated immunomodulatory therapy and high-quality supportive care can help clinicians avoid causing iatrogenic harm in patients with MIS-C.

Rapid, scalable assessment of SARS-CoV-2 cellular immunity by whole-blood PCR.

Fast, high-throughput methods for measuring the level and duration of protective immune responses to SARS-CoV-2 are needed to anticipate the risk of breakthrough infections. Here we report the development of two quantitative PCR assays for SARS-CoV-2-specific T cell activation. The assays are rapid, internally normalized and probe-based: qTACT requires RNA extraction and dqTACT avoids sample preparation steps. Both assays rely on the quantification of CXCL10 messenger RNA, a chemokine whose expression is strongly correlated with activation of antigen-specific T cells. On restimulation of whole-blood cells with SARS-CoV-2 viral antigens, viral-specific T cells secrete IFN-γ, which stimulates monocytes to produce CXCL10. CXCL10 mRNA can thus serve as a proxy to quantify cellular immunity. Our assays may allow large-scale monitoring of the magnitude and duration of functional T cell immunity to SARS-CoV-2, thus helping to prioritize revaccination strategies in vulnerable populations.

Differential effects of the second SARS-CoV-2 mRNA vaccine dose on T cell immunity in naive and COVID-19 recovered individuals.

The rapid development of mRNA-based vaccines against the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) led to the design of accelerated vaccination schedules that have been extremely effective in naive individuals. While a two-dose immunization regimen with the BNT162b2 vaccine has been demonstrated to provide a 95% efficacy in naive individuals, the effects of the second vaccine dose in individuals who have previously recovered from natural SARS-CoV-2 infection has not been investigated in detail. In this study, we characterize SARS-CoV-2 spike-specific humoral and cellular immunity in naive and previously infected individuals during and after two doses of BNT162b2 vaccination. Our results demonstrate that, while the second dose increases both the humoral and cellular immunity in naive individuals, COVID-19 recovered individuals reach their peak of immunity after the first dose. These results suggests that a second dose, according to the current standard regimen of vaccination, may be not necessary in individuals previously infected with SARS-CoV-2.

COVID-19 and Pembrolizumab-Induced Secondary Hemophagocytic Lymphohistiocytosis: a Case Report.

Our case highlights SARS-CoV-2 and pembrolizumab as trigger of secondary hemophagocytic lymphohistiocytosis. Although it is a rare complication, it must be suspected in order to start specific treatment. In this context, intravenous immunoglobulins could be a therapeutic option.

Cytokine Profile in Children with Severe Multisystem Inflammatory Syndrome Related to the Coronavirus Disease 2019.

The multisystem inflammatory syndrome in children (MIS-C) is a novel and concerning entity related to severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection. Although MIS-C has been the subject of intensive research efforts, its pathophysiology and optimal treatment remain elusive. We studied the clinical features, laboratory findings, and immunoinflammatory profiles of seven children prospectively admitted to a pediatric intensive care unit (PICU) during the first wave of the pandemic. All patients had immunoglobulin (Ig)-G against SARS-CoV-2, four of seven patients had both IgM and IgG, and in one of the 7 SARS-CoV-2 was detected in a respiratory sample. All patients received intravenous fluid boluses (median: 15 mL/kg) and norepinephrine. The most common form of respiratory support was supplemental oxygen via nasal cannula. None of the patients needed mechanical ventilation. The cardiovascular system was frequently involved. All patients had an elevated troponin-I (median: 107.3 ng/L). Four out of seven patients had coronary artery abnormalities, and two of seven had both abnormal electrocardiogram (EKG) findings and evidence of left ventricular dysfunction on echocardiogram. Ig levels and complement function were normal. Peripheral blood phenotyping with flow cytometry showed decreased T-cell numbers at the expense of CD8+ T-cells. Cytokine profiling showed a heterogeneous increase in interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, IL-18, IL-2Ra, IL-10, and IL-1Ra that tended to normalize after treatment. Our study shows that children with MIS-C have elevated plasma levels of pro- and anti-inflammatory cytokines in the acute phase of the disease without other relevant immunologic disturbances. These findings suggest the presence of a mixed antagonist response syndrome (MARS) similar to that present in pediatric sepsis. Combining a meticulous differential diagnosis with cautiously coordinated immunomodulatory therapy and high-quality supportive care can help clinicians avoid causing iatrogenic harm in patients with MIS-C.

SARS-CoV-2 Cysteine-like Protease Antibodies Can Be Detected in Serum and Saliva of COVID-19-Seropositive Individuals.

Currently, there is a need for reliable tests that allow identification of individuals that have been infected with SARS-CoV-2 even if the infection was asymptomatic. To date, the vast majority of the serological tests for SARS-CoV-2-specific Abs are based on serum detection of Abs to either the viral spike glycoprotein (the major target for neutralizing Abs) or the viral nucleocapsid protein that is known to be highly immunogenic in other coronaviruses. Conceivably, exposure of Ags released from infected cells could stimulate Ab responses that might correlate with tissue damage and, hence, they may have some value as a prognostic indicator. We addressed whether other nonstructural viral proteins, not incorporated into the infectious viral particle, specifically the viral cysteine-like protease, might also be potent immunogens. Using ELISA tests, coating several SARS-CoV-2 proteins produced in vitro, we describe that COVID-19 patients make high titer IgG, IgM, and IgA Ab responses to the Cys-like protease from SARS-CoV-2, also known as 3CLpro or Mpro, and it can be used to identify individuals with positive serology against the coronavirus. Higher Ab titers in these assays associated with more-severe disease, and no cross-reactive Abs against prior betacoronavirus were found. Remarkably, IgG Abs specific for Mpro and other SARS-CoV-2 Ags can also be detected in saliva. In conclusion, Mpro is a potent Ag in infected patients that can be used in serological tests, and its detection in saliva could be the basis for a rapid, noninvasive test for COVID-19 seropositivity.

Coronavirus disease 2019 in patients with inborn errors of immunity: An international study.

BACKGROUND: There is uncertainty about the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in individuals with rare inborn errors of immunity (IEI), a population at risk of developing severe coronavirus disease 2019. This is relevant not only for these patients but also for the general population, because studies of IEIs can unveil key requirements for host defense. OBJECTIVE: We sought to describe the presentation, manifestations, and outcome of SARS-CoV-2 infection in IEI to inform physicians and enhance understanding of host defense against SARS-CoV-2. METHODS: An invitation to participate in a retrospective study was distributed globally to scientific, medical, and patient societies involved in the care and advocacy for patients with IEI. RESULTS: We gathered information on 94 patients with IEI with SARS-CoV-2 infection. Their median age was 25 to 34 years. Fifty-three patients (56%) suffered from primary antibody deficiency, 9 (9.6%) had immune dysregulation syndrome, 6 (6.4%) a phagocyte defect, 7 (7.4%) an autoinflammatory disorder, 14 (15%) a combined immunodeficiency, 3 (3%) an innate immune defect, and 2 (2%) bone marrow failure. Ten were asymptomatic, 25 were treated as outpatients, 28 required admission without intensive care or ventilation, 13 required noninvasive ventilation or oxygen administration, 18 were admitted to intensive care units, 12 required invasive ventilation, and 3 required extracorporeal membrane oxygenation. Nine patients (7 adults and 2 children) died. CONCLUSIONS: This study demonstrates that (1) more than 30% of patients with IEI had mild coronavirus disease 2019 (COVID-19) and (2) risk factors predisposing to severe disease/mortality in the general population also seemed to affect patients with IEI, including more younger patients. Further studies will identify pathways that are associated with increased risk of severe disease and are nonredundant or redundant for protection against SARS-CoV-2.