The titers of antinuclear antibodies are associated with the degree of inflammation and organ damage in Primary Sjögren's Syndrome.

Primary Sjögren's Syndrome (pSS) falls within the category of connective tissue diseases, characterized by the presence of autoantibodies such as antinuclear antibodies (ANA). However, according to the classification criteria for pSS, some patients may exhibit a negative result for autoantibodies. Patients with a negative result for autoantibodies may lack typical features of connective tissue diseases, and the immunological state as well as the extent of organ involvement and damage may differ from those with positive autoantibodies. This study aims to compare the clinical phenotypes of patients with positive and negative autoantibodies, providing insights for disease classification and treatment selection for clinicians. Patients with pSS were grouped based on the presence and titers of their autoantibodies. Subsequently, differences in organ damage and laboratory indicators were compared between these groups, aiming to analyze the value of autoantibody titers in assessing the condition of pSS. (1) Patients with positive ANA exhibited elevated levels of inflammatory indicators, including ESR, IgG levels, lip gland biopsy pathology grade, and overall organ involvement, in comparison with patients with negative ANA (P < 0.05). Furthermore, ANA-positivity correlated with a higher occurrence of multi-organ damage, particularly affecting the skin, mucous membranes, and the hematological system (P < 0.05). (2) As ANA titers increased, patients demonstrated elevated levels of IgG and an escalation in organ involvement (P < 0.05). (3) Patients in the positive autoantibody group (positive for antinuclear antibodies, anti-SSA, or anti-SSB antibodies) had higher IgG levels compared to the negative group (P < 0.05). (4) Patients with positive anti-SSA and anti-SSB antibodies exhibited higher levels of inflammatory indicators and IgG compared to other patients (P < 0.05); however, no significant differences were observed in terms of organ involvement and organ damage. Patients with positive ANA in pSS typically exhibit higher levels of inflammation and an increased likelihood of experiencing multi-organ damage. Furthermore, as the ANA titers increase, both inflammation levels and the risk of multi-organ damage also escalate. Additionally, the presence of anti-SSA and anti-SSB antibodies may contribute to an elevated risk of increased inflammation levels, but does not increase the risk of organ damage.

Evaluation of SARS-CoV-2 interferon gamma release assay in BNT162b2 vaccinated healthcare workers.

To predict protective immunity to SARS-CoV-2, cellular immunity seems to be more sensitive than humoral immunity. Through an Interferon-Gamma (IFN-γ) Release Assay (IGRA), we show that, despite a marked decrease in total antibodies, 94.3% of 123 healthcare workers have a positive cellular response 6 months after inoculation with the 2nd dose of BNT162b2 vaccine. Despite the qualitative relationship found, we did not observe a quantitative correlation between IFN-γ and IgG levels against SARS-CoV-2. Using stimulated whole blood from a subset of participants, we confirmed the specific T-cell response to SARS-CoV-2 by dosing elevated levels of the IL-6, IL-10 and TNF-α. Through a 20-month follow-up, we found that none of the infected participants had severe COVID-19 and that the first positive cases were only 12 months after the 2nd dose inoculation. Future studies are needed to understand if IGRA-SARS-CoV-2 can be a powerful diagnostic tool to predict future COVID-19 severe disease, guiding vaccination policies.

Efficient transplacental transfer of SARS-CoV-2 antibodies between naturally exposed mothers and infants in Accra, Ghana.

We aimed to determine SARS-CoV-2 antibody seropositivity among pregnant women and the transplacental transfer efficiency of SARS-CoV-2-specific antibodies relative to malaria antibodies among SARS-CoV-2 seropositive mother-cord pairs. This cross-sectional study was conducted in Accra, Ghana, from March to May 2022. Antigen- specific IgG antibodies against SARS-CoV-2 (nucleoprotein and spike-receptor binding domain) and malarial antigens (circumsporozoite protein and merozoite surface protein 3) in maternal and cord plasma were measured by ELISA. Plasma from both vaccinated and unvaccinated pregnant women were tested for neutralizing antibodies using commercial kit. Of the unvaccinated pregnant women tested, 58.12% at antenatal clinics and 55.56% at the delivery wards were seropositive for both SARS-CoV-2 nucleoprotein and RBD antibodies. Anti-SARS-CoV-2 antibodies in cord samples correlated with maternal antibody levels (N antigen rs = 0.7155, p < 0.001; RBD rs = 0.8693, p < 0.001). Transplacental transfer of SARS-CoV-2 nucleoprotein antibodies was comparable to circumsporozoite protein antibodies (p = 0.9999) but both were higher than transfer rates of merozoite surface protein 3 antibodies (p < 0.001). SARS-CoV-2 IgG seropositivity among pregnant women in Accra is high with a boost of SARS-CoV-2 RBD-specific IgG in vaccinated women. Transplacental transfer of anti-SARS-CoV-2 and malarial antibodies was efficient, supporting vaccination of mothers as a strategy to protect infants against SARS-CoV-2.

Autoimmune hepatitis displays distinctively high multi-antennary sialylation on plasma N-glycans compared to other liver diseases.

BACKGROUND: Changes in plasma protein glycosylation are known to functionally affect proteins and to associate with liver diseases, including cirrhosis and hepatocellular carcinoma. Autoimmune hepatitis (AIH) is a liver disease characterized by liver inflammation and raised serum levels of IgG, and is difficult to distinguish from other liver diseases. The aim of this study was to examine plasma and IgG-specific N-glycosylation in AIH and compare it with healthy controls and other liver diseases. METHODS: In this cross-sectional cohort study, total plasma N-glycosylation and IgG Fc glycosylation analysis was performed by mass spectrometry for 66 AIH patients, 60 age- and sex-matched healthy controls, 31 primary biliary cholangitis patients, 10 primary sclerosing cholangitis patients, 30 non-alcoholic fatty liver disease patients and 74 patients with viral or alcoholic hepatitis. A total of 121 glycans were quantified per individual. Associations between glycosylation traits and AIH were investigated as compared to healthy controls and other liver diseases. RESULTS: Glycan traits bisection (OR: 3.78 [1.88-9.35], p-value: 5.88 × 10- 3), tetraantennary sialylation per galactose (A4GS) (OR: 2.88 [1.75-5.16], p-value: 1.63 × 10- 3), IgG1 galactosylation (OR: 0.35 [0.2-0.58], p-value: 3.47 × 10- 5) and hybrid type glycans (OR: 2.73 [1.67-4.89], p-value: 2.31 × 10- 3) were found as discriminators between AIH and healthy controls. High A4GS differentiated AIH from other liver diseases, while bisection associated with cirrhosis severity. CONCLUSIONS: Compared to other liver diseases, AIH shows distinctively high A4GS levels in plasma, with potential implications on glycoprotein function and clearance. Plasma-derived glycosylation has potential to be used as a diagnostic marker for AIH in the future. This may alleviate the need for a liver biopsy at diagnosis. Glycosidic changes should be investigated further in longitudinal studies and may be used for diagnostic and monitoring purposes in the future.

Exploiting the neonatal crystallizable fragment receptor to treat kidney disease.

The neonatal Fc receptor (FcRn) was initially discovered as the receptor that allowed passive immunity in newborns by transporting maternal IgG through the placenta and enterocytes. Since its initial discovery, FcRn has been found to exist throughout all stages of life and in many different cell types. Beyond passive immunity, FcRn is necessary for intrinsic albumin and IgG recycling and is important for antigen processing and presentation. Given its multiple important roles, FcRn has been utilized in many disease treatments including a new class of agents that were developed to inhibit FcRn for treatment of a variety of autoimmune diseases. Certain cell populations within the kidney also express high levels of this receptor. Specifically, podocytes, proximal tubule epithelial cells, and vascular endothelial cells have been found to utilize FcRn. In this review, we summarize what is known about FcRn and its function within the kidney. We also discuss how FcRn has been used for therapeutic benefit, including how newer FcRn inhibiting agents are being used to treat autoimmune diseases. Lastly, we will discuss what renal diseases may respond to FcRn inhibitors and how further work studying FcRn within the kidney may lead to therapies for kidney diseases.

Maternal immunoglobulin G affects brain development of mouse offspring.

Maternal immunoglobulin (Ig)G is present in breast milk and has been shown to contribute to the development of the immune system in infants. In contrast, maternal IgG has no known effect on early childhood brain development. We found maternal IgG immunoreactivity in microglia, which are resident macrophages of the central nervous system of the pup brain, peaking at postnatal one week. Strong IgG immunoreactivity was observed in microglia in the corpus callosum and cerebellar white matter. IgG stimulation of primary cultured microglia activated the type I interferon feedback loop by Syk. Analysis of neonatal Fc receptor knockout (FcRn KO) mice that could not take up IgG from their mothers revealed abnormalities in the proliferation and/or survival of microglia, oligodendrocytes, and some types of interneurons. Moreover, FcRn KO mice also exhibited abnormalities in social behavior and lower locomotor activity in their home cages. Thus, changes in the mother-derived IgG levels affect brain development in offsprings.

Hybrid response to SARS-CoV-2 and Neisseria meningitidis C after an OMV-adjuvanted immunization in mice and their offspring.

COVID-19, caused by SARS-CoV-2, and meningococcal disease, caused by Neisseria meningitidis, are relevant infectious diseases, preventable through vaccination. Outer membrane vesicles (OMVs), released from Gram-negative bacteria, such as N. meningitidis, present adjuvant characteristics and may confer protection against meningococcal disease. Here, we evaluated in mice the humoral and cellular immune response to different doses of receptor binding domain (RBD) of SARS-CoV-2 adjuvanted by N. meningitidis C:2a:P1.5 OMVs and aluminum hydroxide, as a combined preparation for these pathogens. The immunization induced IgG antibodies of high avidity for RBD and OMVs, besides IgG that recognized the Omicron BA.2 variant of SARS-CoV-2 with intermediary avidity. Cellular immunity showed IFN-γ and IL-4 secretion in response to RBD and OMV stimuli, demonstrating immunologic memory and a mixed Th1/Th2 response. Offspring presented transferred IgG of similar levels and avidity as their mothers. Humoral immunity did not point to the superiority of any RBD dose, but the group immunized with a lower antigenic dose (0.5 µg) had the better cellular response. Overall, OMVs enhanced RBD immunogenicity and conferred an immune response directed to N. meningitidis too.

A case report of IgG4-related hepatic inflammatory pseudotumor in a 3-year old boy.

Background: Hepatic Inflammatory Pseudotumor (IPT) is an infrequent condition often masquerading as a malignant tumor, resulting in misdiagnosis and unnecessary surgical resection. The emerging concept of IgG4-related diseases (IgG4-RD) has gained widespread recognition, encompassing entities like IgG4-related hepatic IPT. Clinically and radiologically, corticosteroids and immunosuppressive therapies have proven effective in managing this condition. Case Presentation: A 3-year-old Chinese boy presented to the clinic with an 11-month history of anemia, fever of unknown origin, and a tender hepatic mass. Blood examinations revealed chronic anemia (Hb: 6.4 g/L, MCV: 68.6 fl, MCH: 19.5 pg, reticulocytes: 1.7%) accompanied by an inflammatory reaction and an elevated serum IgG4 level (1542.2 mg/L). Abdominal contrast-enhanced computed tomography unveiled a 7.6 cm low-density mass in the right lateral lobe, while magnetic resonance imaging demonstrated slight hypointensity on T1-weighted images and slight hyperintensity on T2-weighted images, prompting suspicion of hepatic malignancy. A subsequent liver biopsy revealed a mass characterized by fibrous stroma and dense lymphoplasmacytic infiltration. Immunohistochemical analysis confirmed the presence of IgG4-positive plasma cells, leading to the diagnosis of IgG4-related hepatic IPT. Swift resolution occurred upon initiation of corticosteroid and mycophenolate mofetil therapies. Conclusion: This study underscores the diagnostic approach to hepatic IPT, utilizing histopathology, immunostaining, imaging, serology, organ involvement, and therapeutic response. Early histological examination plays a pivotal role in clinical guidance, averting misdiagnosis as a liver tumor and unnecessary surgical interventions.

Baseline immunoglobulin G and immune function in non-Hodgkin lymphoma: a retrospective analysis.

Introduction: Non-Hodgkin's lymphoma (NHL) encompasses a diverse group of lymphoma subtypes with a wide range in disease course. Previous studies show that hypogammaglobulinemia in treatment-naïve patients is associated with poorer survival in high grade B-cell non-Hodgkin's lymphomas, though it is not known how this applies across all B-cell lymphoid malignancies. Methods: We conducted a retrospective study of immunoglobulin levels and clinical outcomes including survival, hospitalization, and infection rates in patients diagnosed with B-cell non-Hodgkin lymphomas of all grades at our institution. Results: Two-hundred twenty-three adults (aged = 18 years) with available pre-treatment IgG levels were selected, with hypogammaglobulinemia defined as IgG< 500 mg/mL. For this analysis, we grouped DLBCL (n=90), Primary CNS (n=5), and Burkitt lymphoma (n=1) together as high-grade, while CLL (n=52), mantle cell (n=20), marginal zone (n=25), follicular (n=21), and Waldenstrom macroglobulinemia (n=5) were low-grade. The incidence of hypogammaglobulinemia in our cohort of both high and low-grade lymphoma patients was 13.5% (n=30). Across all NHL subtypes, individuals with baseline IgG< 500 mg/dL showed an increased rate of hospitalization (4.453, CI: 1.955-10.54, p= 0.0005) and higher mortality (3.325, CI: 1.258, 8.491, p= 0.013), yet no association in number of infections when compared with those with IgG=500 mg/dL. There was a higher hospitalization rate (3.237, CI: 1.77-6.051, p=0.0017) in those with high-grade lymphoma with hypogammaglobulinemia when compared with low-grade. There was no statistically significant difference in individuals who were alive after three years in those with baseline IgG<500 mg/dL. Discussion: Our study is the first to analyze incidence of hypogammaglobulinemia at the time of diagnosis of NHL as a potential biomarker of interest for future outcomes including hospitalization and infection.

Inter-assay diagnostic accuracy of cerebrospinal fluid kappa free light chains for the diagnosis of multiple sclerosis.

Background: Cerebrospinal fluid (CSF) kappa free light chain (κFLC) measures gained increasing interest as diagnostic markers in multiple sclerosis (MS). However, the lack of studies comparing assay-dependent diagnostic cutoff values hinders their use in clinical practice. Additionally, the optimal κFLC parameter for identifying MS remains a subject of ongoing debate. Objectives: The aim of this study was to compare same-sample diagnostic accuracies of the κFLC index, κIgG index, CSF κFLC/IgG ratio, and isolated CSF κFLC (iCSF-κFLC) between two reference centers using different methods. Methods: Paired serum and CSF samples were analyzed for κFLC and albumin concentrations by Freelite®-Optilite (Sint-Jan Bruges hospital) and N Latex®-BNII (Ghent University hospital). Diagnostic performance to differentiate MS from controls was assessed using ROC curve analysis. Results: A total of 263 participants were included (MS, n = 80). Optimal diagnostic cutoff values for the κFLC index (Freelite®-Optilite: 7.7; N Latex®-BNII: 4.71), κIgG index (Freelite®-Optilite: 14.15, N Latex®-BNII: 12.19), and CSF κFLC/IgG ratio (Freelite®-Optilite: 2.27; N Latex®-BNII: 1.44) differed between the two methods. Sensitivities related to optimal cutoff values were 89.9% (Freelite®-Optilite) versus 94.6% (N Latex®-BNII) for the κFLC index, 91% (Freelite®-Optilite) versus 92.2% (N Latex®-BNII) for the κIgG index, and 81.3% (Freelite®-Optilite) versus 91.4% (N Latex®-BNII) for the CSF κFLC/IgG ratio. However, for iCSF-κFLC, optimal diagnostic cutoff values (0.36 mg/L) and related specificities (81.8%) were identical with a related diagnostic sensitivity of 89.9% for Freelite®-Optilite and 90.5% for N Latex®-BNII. The diagnostic performance of the κFLC index [area under the curve (AUC) Freelite®-Optilite: 0.924; N Latex®-BNII: 0.962] and κIgG index (AUC Freelite®-Optilite: 0.929; N Latex®-BNII: 0.961) was superior compared to CSF oligoclonal bands (AUC: 0.898, sensitivity: 83.8%, specificity: 95.9%). Conclusions: The κFLC index and the κIgG index seem to be excellent markers for identifying MS, irrespective of the method used for κFLC quantification. Based on the AUC, they appear to be the measures of choice. For all measures, optimal cutoff values differed between methods except for iCSF-κFLC. iCSF-κFLC might therefore serve as a method-independent, more cost-efficient, initial screening measure for MS. These findings are particularly relevant for clinical practice given the potential future implementation of intrathecal κFLC synthesis in MS diagnostic criteria and for future multicentre studies pooling data on κFLC measures.

Establishment of two serological methods for detecting IgG and neutralizing antibodies against Crimean-Congo hemorrhagic fever virus glycoprotein.

Introduction: The Crimean-Congo hemorrhagic fever virus (CCHFV), the most geographically widespread tick-borne virus, is endemic in Africa, Eastern Europe and Asia, with infection resulting in mortality in up to 30% of cases. Currently, there are no approved vaccines or effective therapies available for CCHF. The CCHFV should only be manipulated in the BSL-4 laboratory, which has severely hampered basic seroprevalence studies. Methods: In the present study, two antibody detection methods in the forms of an enzyme-linked immunosorbent assay (ELISA) and a surrogate virus neutralization test (sPVNT) were developed using a recombinant glycoprotein (rGP) and a vesicular stomatitis virus (VSV)-based virus bearing the CCHFV recombinant glycoprotein (rVSV/CCHFV) in a biosafety level 2 (BSL-2) laboratory, respectively. Results: The rGP-based ELISA and rVSV/CCHFV-based sVNT were established by using the anti-CCHFV pre-GC mAb 11E7, known as a broadly cross-reactive, potently neutralizing antibody, and their applications as diagnostic antigens were validated for the specific detection of CCHFV IgG and neutralizing antibodies in experimental animals. In two tests, mAb clone 11E7 (diluted at 1:163840 or 512) still displayed positive binding and neutralization, and the presence of antibodies (IgG and neutralizing) against the rGP and rVSV/CCHFV was also determined in the sera from the experimental animals. Both mAb 11E7 and animal sera showed a high reactivity to both antigens, indicating that bacterially expressed rGP and rVSV/CCHFV have good immunoreactivity. Apart from establishing two serological testing methods, their results also demonstrated an imperfect correlation between IgG and neutralizing antibodies. Discussion: Within this limited number of samples, the rGP and rVSV/CCHFV could be safe and convenient tools with significant potential for research on specific antibodies and serological samples.

Salivary immunoglobulin levels and periodontal indices in Brazilian children with and without type 1 diabetes.

This cross-sectional study evaluated the association between salivary immunoglobulins, plaque index, and gingival index in Brazilian children with and without type 1 diabetes mellitus (DM1). The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist for the reporting of observational studies was followed. The DM1 group had 38 children, and an equal number of volunteers matched by sex and age were recruited as controls. Clinical examination was performed for plaque index and gingival index determination. Non-stimulated whole saliva was collected. Concentrations of IgA, IgG, and IgM were determined by ELISA test. Data were tested by the Kolmogorov-Smirnov, Mann-Whitney, and Spearman tests and a multiple linear regression model (p<0.05) was performed. Gingival index was higher in the Control (DM1: 0.16±0.17; Control: 0.24±0.23, p=0.040). In DM1, there was a correlation between IgA and age (rho=0.371, p=0.024), IgM and IgG (rho=0.459, p=0.007), and IgM and gingival index (rho=0.394, p=0.014). In DM1, multiple linear regression showed that age (p=0.041; ß=0.363), gingival index (p=0.041; ß=0.398), and plaque index (p=0.008; ß=-0.506) were good predictors of IgA levels in saliva. Thus, IgA was the only researched immunoglobulin that was directly associated with plaque and gingival indices in Brazilian children with DM1, but not in control subjects.

Development of an antibody against EtpA from enterotoxigenic Escherichia coli and evaluation of its use for bacterial isolation using magnetic beads.

The enterotoxigenic Escherichia coli (ETEC) strain is one of the most frequent causative agents of childhood diarrhea and travelers' diarrhea in low-and middle-income countries. Among the virulence factors secreted by ETEC, the exoprotein EtpA has been described as an important. In the present study, a new detection tool for enterotoxigenic E. coli bacteria using the EtpA protein was developed. Initially, antigenic sequences of the EtpA protein were selected via in silico prediction. A chimeric recombinant protein, corresponding to the selected regions, was expressed in an E. coli host, purified and used for the immunization of mice. The specific recognition of anti-EtpA IgG antibodies generated was evaluated using flow cytometry. The tests demonstrated that the antibodiesdeveloped were able to recognize the native EtpA protein. By coupling these antibodies to magnetic beads for the capture and detection of ETEC isolates, cytometric analyses showed an increase in sensitivity, specificity and the effectiveness of the method of separation and detection of these pathogens. This is the first report of the use of this methodology for ETEC separation. Future trials may indicate their potential use for isolating these and other pathogens in clinical samples, thus accelerating the diagnosis and treatment of diseases.

Immunoglobulin G4 (IgG4) Positive Associated Liver Disease.

BACKGROUND: The goal was to explore the cognition of diagnosis and treatment level of IgG4-related diseases mainly involving lymph nodes. METHODS: The clinical manifestations, laboratory indicators, histopathology, and therapeutic effects of a patient with IgG4-RD suspected of lymphoma were analyzed and the relevant literature was reviewed. RESULTS: Lymph node biopsy showed reactive hyperplasia of lymph node tissue. The liver biochemical indexes were abnormal and the bone marrow smear showed atypical lymphocytes. Lymph node section: IgG4+ cells > 100/HPF (IgG4/IgG > 40%). The serum IgG4 level was 17,200 mg/L, and the diagnosis was IgG4-RD. Oral glucocorticoids took effect after 2 weeks, and no significant enlargement of lymph nodes was observed. CONCLUSIONS: For the diagnosis of IgG4-RD, at present, histopathology is still the gold standard, but a single result cannot diagnose the disease. Comprehensive judgment should be made by combining clinical symptoms, serum IgG4 level and imaging results to prevent misdiagnosis and missed diagnosis, and to avoid over-diagnosis. Short-term hormonal diagnostic therapy may be used in highly suspected patients who cannot be diagnosed. Once diagnosed, standardized medication, adhere to follow-up, regular review, to prevent recurrence and adverse drug reactions.

Measles IgG Avidity Assay.

Measles IgG avidity assays determine the overall strength of molecular binding between measles-specific IgG antibodies and measles virus antigens. Avidity results can distinguish recent from distant measles virus infections. Individuals who are immunologically naïve to measles virus develop low-avidity antibodies upon measles virus infection or first-time vaccination. Within 4-6 months, antibodies mature to high avidity. Measles avidity assays are most useful in the context of measles elimination. In such settings, avidity and epidemiological and clinical information are used to classify measles breakthrough infections for control and surveillance purposes and to assist in case confirmation when other laboratory results are inconclusive or nonexistent. We present a highly accurate end-titer measles avidity assay that delivers results based on IgG quality (avidity) that are independent of IgG concentration.

Multiplex Bead Assay for the Serological Surveillance of Measles and Rubella.

There is increasing interest in evaluating antibody responses to multiple antigen targets in a single assay. Immunity to measles and rubella are often evaluated together because immunity is provided through combined vaccines and because routine immunization efforts and surveillance for measles and rubella pathogens are combined in many countries. The multiplex bead assay (MBA) also known as the multiplex immunoassay (MIA) described here combines the measurement of measles- and rubella-specific IgG antibodies in serum quantitatively according to international serum standards and has been successfully utilized in integrated serological surveillance.

Identification and characterization of a nonbiological small-molecular mimic of a Zika virus conformational neutralizing epitope.

Antigenic similarities between Zika virus (ZIKV) and other flaviviruses pose challenges to the development of virus-specific diagnostic tools and effective vaccines. Starting with a DNA-encoded one-bead-one-compound combinatorial library of 508,032 synthetic, non-natural oligomers, we selected and characterized small molecules that mimic ZIKV epitopes. High-throughput fluorescence-activated cell sorter-based bead screening was used to select molecules that bound IgG from ZIKV-immune but not from dengue-immune sera. Deep sequencing of the DNA from the "Zika-only" beads identified 40 candidate molecular structures. A lead candidate small molecule "CZV1-1" was selected that correctly identifies serum specimens from Zika-experienced patients with good sensitivity and specificity (85.3% and 98.4%, respectively). Binding competition studies of purified anti-CZV1-1 IgG against known ZIKV-specific monoclonal antibodies (mAbs) showed that CZV1-1 mimics a nonlinear, neutralizing conformational epitope in the domain III of the ZIKV envelope. Purified anti-CZV1-1 IgG neutralized infection of ZIKV in cell cultures with potencies comparable to highly specific ZIKV-neutralizing mAbs. This study demonstrates an innovative approach for identification of synthetic non-natural molecular mimics of conformational virus epitopes. Such molecular mimics may have value in the development of accurate diagnostic assays for Zika, as well as for other viruses.

IgG subclass levels in referred hemochromatosis probands with HFE p.C282Y/p.C282Y.

BACKGROUND: IgG subclass levels in hemochromatosis are incompletely characterized. METHODS: We characterized IgG subclass levels of referred hemochromatosis probands with HFE p.C282Y/p.C282Y (rs1800562) and human leukocyte antigen (HLA)-A and -B typing/haplotyping and compared them with IgG subclass levels of eight published cohorts of adults unselected for hemochromatosis. RESULTS: There were 157 probands (82 men, 75 women; mean age 49±13 y). Median serum ferritin, mean body mass index (BMI), median IgG4, and median phlebotomy units to achieve iron depletion were significantly higher in men. Diabetes, cirrhosis, and HLA-A*03,-B*44, -A*03,B*07, and -A*01,B*08 prevalences and median absolute lymphocyte counts in men and women did not differ significantly. Mean IgG subclass levels [95% confidence interval] were: IgG1 5.31 g/L [3.04, 9.89]; IgG2 3.56 g/L [1.29, 5.75]; IgG3 0.61 g/L [0.17, 1.40]; and IgG4 0.26 g/L [<0.01, 1.25]. Relative IgG subclasses were 54.5%, 36.6%, 6.3%, and 2.7%, respectively. Median IgG4 was higher in men than women (0.34 g/L [0.01, 1.33] vs. 0.19 g/L [<0.01, 0.75], respectively; p = 0.0006). A correlation matrix with Bonferroni correction revealed the following positive correlations: IgG1 vs. IgG3 (p<0.01); IgG2 vs. IgG3 (p<0.05); and IgG2 vs. IgG4 (p<0.05). There was also a positive correlation of IgG4 vs. male sex (p<0.01). Mean IgG1 was lower and mean IgG2 was higher in probands than seven of eight published adult cohorts unselected for hemochromatosis diagnoses. CONCLUSIONS: Mean IgG subclass levels of hemochromatosis probands were 5.31, 3.56, 0.61, and 0.26 g/L, respectively. Median IgG4 was higher in men than women. There were positive associations of IgG subclass levels. Mean IgG1 may be lower and mean IgG2 may be higher in hemochromatosis probands than adults unselected for hemochromatosis.

DNA Nanostructure-Templated Antibody Complexes Provide Insights into the Geometric Requirements of Human Complement Cascade Activation.

The classical complement pathway is activated by antigen-bound IgG antibodies. Monomeric IgG must oligomerize to activate complement via the hexameric C1q complex, and hexamerizing mutants of IgG appear as promising therapeutic candidates. However, structural data have shown that it is not necessary to bind all six C1q arms to initiate complement, revealing a symmetry mismatch between C1 and the hexameric IgG complex that has not been adequately explained. Here, we use DNA nanotechnology to produce specific nanostructures to template antigens and thereby spatially control IgG valency. These DNA-nanotemplated IgG complexes can activate complement on cell-mimetic lipid membranes, which enabled us to determine the effect of IgG valency on complement activation without the requirement to mutate antibodies. We investigated this using biophysical assays together with 3D cryo-electron tomography. Our data revealed the importance of interantigen distance on antibody-mediated complement activation, and that the cleavage of complement component C4 by the C1 complex is proportional to the number of ideally spaced antigens. Increased IgG valency also translated to better terminal pathway activation and membrane attack complex formation. Together, these data provide insights into how nanopatterning antigen-antibody complexes influence the activation of the C1 complex and suggest routes to modulate complement activation by antibody engineering. Furthermore, to our knowledge, this is the first time DNA nanotechnology has been used to study the activation of the complement system.