IgG Activity Research Articles

Natural IgG against S-Protein and RBD of SARS-CoV-2 Do Not Bind and Hydrolyze DNA and Are Not Autoimmune.

Since the onset of the COVID-19 pandemic, numerous publications have appeared describing autoimmune pathologies developing after a coronavirus infection, with several papers reporting autoantibody production during the acute period of the disease. Several viral diseases are known to trigger autoimmune processes, and the appearance of catalytic antibodies with DNase activity is one of the earliest markers of several autoimmune pathologies. Therefore, we analyzed whether IgG antibodies from blood plasma of SARS-CoV-2 patients after recovery could bind and hydrolyze DNA. We analyzed how vaccination of patients with adenovirus Sputnik V vaccine influences the production of abzymes with DNase activity. Four groups were selected for the analysis, each containing 25 patients according to their relative titers of antibodies to S-protein: with high and median titers, vaccinated with Sputnik V with high titers, and a control group of donors with negative titers. The relative titers of antibodies against DNA and the relative DNase activity of IgGs depended very much on the individual patient and the donor, and no significant correlation was found between the relative values of antibodies titers and their DNase activity. Our results indicate that COVID-19 disease and vaccination with adenoviral Sputnik V vaccine do not result in the development or enhancement of strong autoimmune reactions as in the typical autoimmune diseases associated with the production of anti-DNA and DNA hydrolyzing antibodies.

Antibodies-Abzymes with Antioxidant Activities in Two Th and 2D2 Experimental Autoimmune Encephalomyelitis Mice during the Development of EAE Pathology.

The exact mechanisms of multiple sclerosis development are still unknown. However, the development of EAE (experimental autoimmune encephalomyelitis) in Th and 2D2 mice is associated with the infringement of the differentiation profiles of bone marrow hematopoietic stem cells which are bound with the production of compounds that are harmful for human autoantibodies-abzymes that hydrolyze myelin oligodendrocyte glycoprotein, myelin basic protein, and DNA. It showed that autoimmune patients' antioxidant IgG antibodies oxidise some compounds due to their peroxidase (H2O2-dependent) and oxidoreductase (H2O2-independent) activities more effectively than those in healthy humans can. It was interesting to identify whether the redox activities of the antibodies change during the development of autoimmune diseases. Here, we analyzed the change in these redox activities of the IgGs from the blood of Th and 2D2 mice, which corresponded to different stages of the EAE development. The peroxidase activity in the oxidation of ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) in the Th (4-fold) and 2D2 (2-fold) mice IgGs, on average, is higher than the oxidoreductase activity is. The peroxidase activity of the Th (1.9-fold) and 2D2 (3.5-fold) mice IgGs remarkably increased during the 40 days of the spontaneous development of EAE. Forty days after the immunization of the MOG peroxidase activity, the IgGs of the Th and 2D2 mice increased 5.6-6.0 times when they were compared with those that presented no increase (3 months of age). The mice IgGs were oxidized with 3,3'-diaminobenzidine (2.4-4.3-fold) and o-phenylenediamine (139-143-fold) less efficiently than they were with ABTS. However, the temper of the change in the IgG activity in the oxidation of these substrates during the spontaneous and MOG-induced development of EAE was close to that which occurred for ABTS. All of the data show that the IgG peroxidase and oxidoreductase activities of EAE mice can play an important role in their protection from toxic compounds and oxidative stress.

Effects of collagen peptides from Micropterus salmoides skin on oxidative damage induced by cyclophosphamide in mice

To investigate the protective effect of collagen peptide from Micropterus salmoides skin (CPMs) on oxidative damage induced by cyclophosphamide in mice. Balb/c female mice were divided into blank, model (cyclophosphamide, CTX), positive control (levamisole hydrochloride), and collagen peptide low-, medium-, and high-dose groups. The results showed that CPMs increase the body mass and immune-related organ indexes, such as liver and kidneys of immunosuppressed mice. The activities of ALT, AST, UA, BUN, and MDA in the liver and kidney tissues decreased significantly, while those of SOD and GSH-Px increased significantly. CPMs can relieve the pathological damage to immune organs. CPMs significantly increase the activities of IL-2, IgG, and TNF-α in serum and SOD activity, while the MDA content was decreased compared to the model group. CPMs can exert a protective effect on cyclophosphamide-induced oxidative damage and have application prospects in the field of health food.

The relationship between the intensity of Gasterophilus intestinalis larvae infection and the serum and salivary humoral immune response in horses

Infection with Gasterophilus intestinalis (botfly) larvae often occurs in horses. The aim of the study was to isolate the larvae of G. intestinalis and evaluate the serum and salivary humoral immune response using self-developed ELISA in G. intestinalis infected horses. Blood serum or saliva samples were taken from 125 infected horses and 54 uninfected slaughtered horses. The antigens from G. intestinalis larvae were used for development of ELISA in order to evaluate the intensity of G. intestinalis IgG, IgM, and IgA antibody reactivity in the serum or saliva of naturally infected horses and horses without larvae in the gastrointestinal tract (control group). Serum antibodies against second and third larvae’s stadium antigens reacted significantly more intensively in infected than in healthy horses in IgG (p ≤ 0.001; p ≤ 0.05, respectively) and IgA (p ≤ 0.05;p ≤ 0.001, respectively) classes. Salivary IgG and IgA specific’s antibody reactivity was significantly higher in horses with moderate (p ≤ 0.01) and severe infection (p ≤ 0.001) compared to the healthy horses. The determination of the G. intestinalis IgG and IgA antibody activity in saliva and serum may be used for detecting horses moderately and severely infested with larvae.

SARS-CoV-2-Neutralizing Humoral IgA Response Occurs Earlier but Is Modest and Diminishes Faster than IgG Response.

Secretory immunoglobulin A (IgA) plays a crucial role in mucosal immunity for preventing the invasion of exogenous antigens; however, little is understood about the neutralizing activity of serum IgA. Here, to examine the role of IgA antibodies against COVID-19 illnesses, we determined the neutralizing activity of serum/plasma IgG and IgA purified from previously SARS-CoV-2-infected and COVID-19 mRNA vaccine-receiving individuals. We found that serum/plasma IgA possesses substantial but rather modest neutralizing activity against SARS-CoV-2 compared to IgG with no significant correlation with the disease severity. Neutralizing IgA and IgG antibodies achieved the greatest activity at approximately 25 and 35 days after symptom onset, respectively. However, neutralizing IgA activity quickly diminished to below the detection limit approximately 70 days after onset, while substantial IgG activity was observed until 200 days after onset. The total neutralizing activity in sera/plasmas of those with COVID-19 largely correlated with those in purified IgG and purified IgA and levels of anti-SARS-CoV-2-S1-binding IgG and anti-SARS-CoV-2-S1-binding IgA. In individuals who were previously infected with SARS-CoV-2 but had no detectable neutralizing IgA activity, a single dose of BNT162b2 or mRNA-1273 elicited potent serum/plasma-neutralizing IgA activity, but the second dose did not further strengthen the neutralization antibody response. The present data show that the systemic immune stimulation with natural infection and COVID-19 mRNA-vaccines elicits both SARS-CoV-2-specific neutralizing IgG and IgA responses in serum, but the IgA response is modest and diminishes faster than the IgG response. IMPORTANCE Secretory dimeric immunoglobulin A (IgA) plays an important role in preventing the invasion of foreign objects by its neutralizing activity on mucosal surfaces, while monomeric serum IgA is thought to relate to the phagocytic immune system activation. Here, we report that individuals with the novel coronavirus disease (COVID-19) developed both systemic neutralizing IgG (nIgG) and IgA (nIgA) active against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the nIgA response was quick and reached the highest activity earlier than the nIgG response, nIgA activity was modest and diminished faster than nIgG activity. In individuals who recovered from COVID-19 but had no detectable nIgA activity, a single dose of COVID-19 mRNA vaccine elicited potent nIgA activity, but the second dose did not further strengthen the antibody response. Our study provides novel insights into the role and the kinetics of serum nIgA against the pathogen in both naturally infected and COVID-19 mRNA vaccine-receiving COVID-19-convalescent individuals.

A protective role of HTLV-1 gp46-specific neutralizing and antibody-dependent cellular cytotoxicity-inducing antibodies in progression to adult T-cell leukemia (ATL).

Human T-cell leukemia virus type-1 (HTLV-1) establishes a long-term persistent infection in humans and causes malignant T-cell leukemia, adult T-cell leukemia (ATL). HTLV-1-specific cytotoxic T lymphocytes have been suggested to play a major role in the immunosurveillance of HTLV-1-infected T cells. However, it remains unclear whether HTLV-1-specific functional antibodies are also involved in the host defense. To explore the role of antibodies in the course of HTLV-1 infection, we quantitated HTLV-1-specific neutralizing and antibody-dependent cellular cytotoxicity (ADCC)-inducing antibody levels in plasma from asymptomatic carriers (ACs) and ATL patients. The levels of neutralizing antibodies, as determined by a syncytium inhibition assay, were significantly lower in acute and chronic ATL patients than in ACs. The levels of ADCC-inducing activity were tested using an autologous pair of HTLV-1-producing cells and cultured natural killer (NK) cells, which showed that the ADCC-inducing activity of IgG at a concentration of 100 µg/ml was comparable between ACs and acute ATL patients. The anti-gp46 antibody IgG levels, determined by ELISA, correlated with those of the neutralizing and ADCC-inducing antibodies. In contrast, the proviral loads did not correlate with any of these antibody levels. NK cells and a monoclonal anti-gp46 antibody reduced the number of HTLV-1 Tax-expressing cells in cultured peripheral blood mononuclear cells from patients with aggressive ATL. These results suggest a protective role for HTLV-1 neutralizing and ADCC-inducing antibodies during the course of HTLV-1 infection.

Serial infection with SARS-CoV-2 Omicron BA.1 and BA.2 following three-dose COVID-19 vaccination.

SARS-CoV-2 Omicron infections are common among individuals who are vaccinated or have recovered from prior variant infection, but few reports have immunologically assessed serial Omicron infections. We characterized SARS-CoV-2 humoral responses in an individual who acquired laboratory-confirmed Omicron BA.1.15 ten weeks after a third dose of BNT162b2, and BA.2 thirteen weeks later. Responses were compared to 124 COVID-19-naive vaccinees. One month post-second and -third vaccine doses, the participant’s wild-type and BA.1-specific IgG, ACE2-displacement and virus neutralization activities were average for a COVID-19-naive triple-vaccinated individual. BA.1 infection boosted the participant’s responses to the cohort ≥95th percentile, but even this strong “hybrid” immunity failed to protect against BA.2. Reinfection increased BA.1 and BA.2-specific responses only modestly. Though vaccines clearly protect against severe disease, results highlight the continued importance of maintaining additional protective measures to counteract the immune-evasive Omicron variant, particularly as vaccine-induced immune responses naturally decline over time.

Immunoglobulins G of Patients with Schizophrenia Protects from Superoxide: Pilot Results.

This study aimed to evaluate the superoxide dismutase (SOD) activity of IgG in patients with schizophrenia. After signing informed consent, we included 67 patients with schizophrenia (34 people with acute schizophrenia and 33 individuals were on outpatient treatment in therapeutic remission) and 14 healthy volunteers. IgGs from blood serum were isolated by affinity chromatography. SOD activity of antibodies was determined spectrophotometrically. We have shown for the first time that IgGs from patients with schizophrenia have SOD activity and this activity is an intrinsic property of antibodies. The maximum increase in SOD activity was registered in the group of patients in therapeutic remission compared with acute schizophrenia (p = 0.005) and in healthy individuals (p = 0.001). Based on the data of inhibitory analysis using a specific SOD inhibitor enzyme, triethylenetetramine (TETA), we can assume that the mechanism of the SOD activity of IgG is similar to the mechanism of classical enzyme catalysis. According to the kinetic analysis, the affinity of the IgGs to the substrate is higher than that of the classical SOD enzyme.

Complement C3a and C3a Receptor Activation Mediates Podocyte Injuries in the Mechanism of Primary Membranous Nephropathy.

The complement system is highly activated in primary membranous nephropathy (MN). Identifying the complement components that damage podocytes has important therapeutic implications. This study investigated the role of C3a and the C3a receptor (C3aR) in the pathogenesis of MN. C3aR expression in kidneys and circulating levels of C3a of MN patients were examined. Human podocyte damage was assessed after exposure to MN plasma +/- C3aR blockade (SB290157, JR14a). C3aR antagonists were administered to rats with Heymann nephritis on day 0 or after proteinuria. Clinical and pathologic parameters, specific IgG and complement activation, and podocyte injuries were then assessed. In the glomeruli, C3aR staining merged well with podocin. Overexpression of C3aR correlated positively with proteinuria, serum creatinine, and no response to treatments. Human podocytes exposed to MN plasma showed increased expression of PLA2R, C3aR, and Wnt3/β-catenin, reduced expression of synaptopodin and migration function, downregulated Bcl-2, and decreased cell viability. C3aR antagonists could block these effects. In Heymann nephritis rats, C3aR blockade attenuated proteinuria, electron-dense deposition, foot process width, and glomerular basement membrane thickening in glomeruli. The increased plasma C3a levels and overexpression of C3aR were also alleviated. Specific, but not total, IgG levels decreased, with less deposition of rat IgG in glomeruli and subsequent reduction of C1q, factor B, and C5b-9. C3a anaphylatoxin is a crucial effector of complement-mediated podocyte damage in MN. The C3aR antagonist may be a potentially viable treatment for this disease.

Response to Oswald etal.: ST6Gal1 in plasma is dispensable for IgG sialylation.

The presence or absence of terminal sialic acid residues in the sugar moiety attached to the Fc-domain of IgG molecules modulates IgG activity and is associated with autoimmune or infection related inflammation. In a recent paper, Oswald and colleagues suggest that IgG sialylation may occur post IgG secretion from plasma cells, which would be a major issue for therapeutic antibodies injected into patients. In contrast, we argue that previous work rather demonstrates that IgG sialylation occurs within B cells and that the experimental system used by the authors is not suitable to address this critical question.

Rhizoma curcumae Longae ameliorates high dietary carbohydrate-induced hepatic oxidative stress, inflammation in golden pompano Trachinotus ovatus

In general, starch, as a complex carbohydrate, is the most economical energy source in aquaculture for its relatively low cost. However, excessive dietary levels of carbohydrate result in pathological conditions. An 8-week feeding trial with CT (control diet, containing 21% carbohydrate), HC (a high-carbohydrate diet, containing 50% carbohydrate) and HCR (a HC diet supplemented with 0.015% Rhizoma curcumae Longae) was performed to investigate the protective effect of curcumin on high-carbohydrate-induced hepatic oxidative stress and intestine lesion in juvenile Trachinotus ovatus. In the current study, HC group significantly decreased WGR, SGR, plasma CAT activity, intestinal C4 levels, hepatic Nrf2, Keap1, Bach1, HO1, CAT, and GPX mRNA expression as well as ZO-1, Occludin, and Claudin-3, TGF-β mRNA transcription levels, while the opposite was true for plasma AST activity, hepatic MDA contents, intestinal Claudin-15, NF-κB, IL-1β, IL-6, and TNF-α mRNA expression. In contrast with the HC group, the HCR group significantly increased the activities of hepatic CAT, SOD, intestinal C3, C4, IgG and LZM levels, hepatic Nrf2, Bach1, CAT, and GPX mRNA expression as well as intestinal ZO-1, Occludin, Claudin-3, TGF-β and IL-10 mRNA expression levels, but the opposite trend was found in plasma triglyceride content, hepatic lipid deposition, hepatic Keap1 mRNA level as well as intestinal NF-κB, IL-6. In conclusion, high-carbohydrate diet can cause detrimental effect on physiological health status in Trachinotus ovatus, while adding Rhizoma curcumae Longae can improve hepatic and intestinal health status via attenuating the oxidative stress, inflammation, and reducing lipid deposition.

Maternal Fc-mediated non-neutralizing antibody responses correlate with protection against congenital human cytomegalovirus infection.

Human cytomegalovirus (HCMV) is the most common congenital infection and a leading cause of stillbirth, neurodevelopmental impairment, and pediatric hearing loss worldwide. Development of a maternal vaccine or therapeutic to prevent congenital HCMV has been hindered by limited knowledge of the immune responses that protect against HCMV transmission in utero. To identify protective antibody responses, we measured HCMV-specific IgG binding and antiviral functions in paired maternal and cord blood sera from HCMV-seropositive transmitting (n = 41) and non-transmitting (n = 40) mother-infant dyads identified via a large, US-based, public cord blood bank. We found that high-avidity IgG binding to HCMV and antibody-dependent cellular phagocytosis (ADCP) were associated with reduced risk of congenital HCMV infection. We also determined that HCMV-specific IgG activation of FcγRI and FcγRII was enhanced in non-transmitting dyads and that increased ADCP responses were mediated through both FcγRI and FcγRIIA expressed on human monocytes. These findings suggest that engagement of FcγRI/FcγRIIA and Fc effector functions including ADCP may protect against congenital HCMV infection. Taken together, these data can guide future prospective studies on immune correlates against congenital HCMV transmission and inform HCMV vaccine and immunotherapeutic development.

Neutralization activity of sera/IgG preparations from fully BNT162b2 vaccinated individuals against SARS-CoV-2 Alpha, Beta, Gamma, Delta, and Kappa variants

In the present prospective study, 225 individuals in Kumamoto General Hospital, Japan, who received two-doses of BNT162b2 vaccine were enrolled/followed up over 150 days and neutralizing activity (NT50) of their sera and antiviral activity (EC50) of IgG purified from sera on day-60 post-1st-dose were determined against wild-type SARS-CoV-2 (SARS-CoV-2Wuhan) (n = 211) and 9 variants (Alpha, Beta, Gamma, Delta, and Kappa) (n = 45). Time-dependent changes of IgG-activity (n = 25) against SARS-CoV-2Wuhan and variants were also examined. Day-60 sera showed reduced NT50 by more than 50% against all variants examined, and greatest reduction was seen with Beta. IgG fractions of high-responders and moderate-responders showed similar fold-changes in EC50 against each variant compared to SARS-CoV-2Wuhan. Evaluation of EC50 of IgG obtained at different time-points (day-28 to -150) revealed time-dependent reduction of activity against all variants. However, against Delta, relatively long-lasting favorable antiviral activity (at least 150 days) was observed. Our data strongly suggest that the successful antecedent scale-up of mRNA-based vaccine administrations in Japan was the primary contributor to the lessening of the otherwise more devastating SARS-CoV-2 pandemic wave caused by the Delta variant. The present data that the effectiveness of vaccine against the then-dominant SARS-CoV-2 variant was likely associated with the moderation of the COVID-19 pandemic wave suggest that as in the case of influenza vaccines, the development of multivalent mRNA-based vaccines represent a generalizable approach to pre-emptively respond pandemic with mutable pathogens.

Catalytic Antibodies in Bipolar Disorder: Serum IgGs Hydrolyze Myelin Basic Protein

The pathogenesis of bipolar affective disorder is associated with immunological imbalances, a general pro-inflammatory status, neuroinflammation, and impaired white matter integrity. Myelin basic protein (MBP) is one of the major proteins in the myelin sheath of brain oligodendrocytes. For the first time, we have shown that IgGs isolated from sera of bipolar patients can effectively hydrolyze human myelin basic protein (MBP), unlike other test proteins. Several stringent criteria were applied to assign the studied activity to serum IgG. The level of MBP-hydrolyzing activity of IgG from patients with bipolar disorder was statistically significantly 1.6-folds higher than that of healthy individuals. This article presents a detailed characterization of the catalytic properties of MBP-hydrolyzing antibodies in bipolar disorder, including the substrate specificity, inhibitory analysis, pH dependence of hydrolysis, and kinetic parameters of IgG-dependent MBP hydrolysis, providing the heterogeneity of polyclonal MBP-hydrolyzing IgGs and their difference from canonical proteases. The ability of serum IgG to hydrolyze MBP in bipolar disorder may become an additional link between the processes of myelin damage and inflammation.

Catalytic activity of serum and immunoglobulins of classes G and A in patients with breast cancer

The objective of this study was to investigate DNase, various types of proteolytic and oxidoreductase serum and abzyme activities, as well as the serum contents of free DNA in patients with breast tumors in accordance with the clinical, pathological and immunohistochemical characteristics of the tumors. It was found that catalytic antibodies isolated from blood serum of patients with breast oncopathology exhibit proteolytic, DNase and oxidoreductase activity, which varies depending on the course of the disease. It is worth noting that catalytic activity of IgAs (per unit of Ig concentration) can be 1-2 orders of magnitude higher than the analogous activity of IgGs. It was found that DNase, proteolytic (cathepsin G, cathepsin B) serum enzymatic activities and cathepsin G-like activity of IgG and IgA differ in patients with malignant and benign breast tumors and in healthy individuals. These parameters depend on the advance of the tumor process, histological and immunohistochemical characteristics of the tumor, as well as on the probability of tumor progression. In particular, the progression of the tumor process is accompanied by an increase of the activity of serum DNase and cathepsin B, decline of the concentration of patients` serum DNA, being also followed by marked changes of the nuclease, proteolytic and oxidoreductase activity of IgG and IgA.

Immunoassay for quantification of antigen-specific IgG fucosylation.

SummaryBackgroundImmunoglobulin G (IgG) antibodies serve a crucial immuno-protective function mediated by IgG Fc receptors (FcγR). Absence of fucose on the highly conserved N-linked glycan in the IgG Fc domain strongly enhances IgG binding and activation of myeloid and natural killer (NK) cell FcγRs. Although afucosylated IgG can provide increased protection (malaria and HIV), it also boosts immunopathologies in alloimmune diseases, COVID-19 and dengue fever. Quantifying IgG fucosylation currently requires sophisticated methods such as liquid chromatography-mass spectrometry (LC-MS) and extensive analytical skills reserved to highly specialized laboratories.MethodsHere, we introduce the Fucose-sensitive Enzyme-linked immunosorbent assay (ELISA) for Antigen-Specific IgG (FEASI), an immunoassay capable of simultaneously quantitating and qualitatively determining IgG responses. FEASI is a two-tier immunoassay; the first assay is used to quantify antigen-specific IgG (IgG ELISA), while the second gives FcγRIIIa binding-dependent readout which is highly sensitive to both the IgG quantity and the IgG Fc fucosylation (FcγR-IgG ELISA).FindingsIgG Fc fucosylation levels, independently determined by LC-MS and FEASI, in COVID-19 responses to the spike (S) antigen, correlated very strongly by simple linear regression (R2=0.93, p < 0.0001). The FEASI method was then used to quantify IgG levels and fucosylation in COVID-19 convalescent plasma which was independently validated by LC-MS.InterpretationFEASI can be reliably implemented to measure relative and absolute IgG Fc fucosylation and quantify binding of antigen-specific IgG to FcγR in a high-throughput manner accessible to all diagnostic and research laboratories.FundingThis work was funded by the Stichting Sanquin Bloedvoorziening (PPOC 19-08 and SQI00041) and ZonMW 10430 01 201 0021.

Anti–Integrin αvβ6 Antibody as a Diagnostic Marker for Pediatric Patients With Ulcerative Colitis

Anti–Integrin αvβ6 Antibody as a Diagnostic Marker for Pediatric Patients With Ulcerative Colitis

Superoxide dismutase activity of serum IgG in acute illness and remission period of schizophrenia

IntroductionAccording to recent research violations of the oxidative-antioxidant balance may play an important role in the pathogenesis of schizophrenia, by changing generate, conduct and reproduce a nerve impulse. Antibodies with oxidoreductase activity may be involved in protection against oxidative stress in schizophrenia.ObjectivesThe study was to compare the superoxide dismutase (SOD) activity of IgG in patients with acute schizophrenia and during remission.MethodsThe study included 20 patients with acute schizophrenia (mean PANSS total score 94,3±14), 18 people with schizophrenia during remission (mean PANSS total score 54,7±9), and 10 healthy individuals. All participants signed informed consent for the research. Isolation of IgG from blood serum was performed using affinity chromatography on Protein-G-Sepharose columns. The homogeneity of the substances is confirmed by the SDS PAGE method. SOD activity of IgG was carried out spectrophotometrically. Statistical processing was conducted with Statistica v.10.ResultsIgG of schizophrenia patients and healthy individuals have a SOD activity and studied activity is proved to be antibodies intrinsic property. The activity of antibodies in acute schizophrenia was 1.7 times higher than in healthy individuals (p&lt;0.05). In patients with schizophrenia during remission SOD activity of IgG was 2.4 times higher than in healthy individuals (p&lt;0.05).ConclusionsWe can assume that in the conditions of oppression antioxidant activity in schizophrenia patients, antibodies partially take over the function of protecting the body from patients with generalized oxidative stress. This work is supported by the Russian Scientific Foundation, grant # 18-15-00053P.DisclosureNo significant relationships.

DNA-hydrolyzing catalytic IgGs from schizophrenia patients do not affect cell viability of the SH-SY5Y human neuroblastoma cell line

IntroductionDNA-hydrolyzing catalytic IgGs have caspase-dependent cytotoxic effects in autoimmune diseases. Recently, DNA-hydrolyzing IgGs have been discovered in schizophrenia. However, their cytotoxic properties have not been studied.ObjectivesTo assess the effect of serum IgGs with DNA-hydrolyzing activity of schizophrenia patients on the cell viability of the SH-SY5Y human neuroblastoma cell line.MethodsSerum of 8 patients with paranoid schizophrenia in the acute phase and 7 mentally and somatically healthy persons were used. IgG was purified from serum by affinity chromatography on Protein-G-Sepharose columns. The DNA hydrolyzing activity of IgG was assessed by the degree of hydrolysis of the pBluescript plasmid. The cell viability of the SH-SY5Y human neuroblastoma cell line after exposure to purified IgG preparations was assessed by high-throughput screening on the CellInsight CX7 platform (Thermo Scientific, USA) using the fluorescent dyes propidium iodide and Hoechst.ResultsOf the 8 IgG preparation obtained, 4 drugs had high DNA-hydrolyzing activity. All tested IgG preparations from healthy donors were inactive. One-way ANOVA analysis of the proportion of dead cells of the SH-SY5Y line after exposure to antibodies (0.1 mg/ml) showed no significant differences in the proportion of dead cells (p=0.688 after 24 hours; p=0.831 after 48 hours). Similar results were obtained at a higher concentration of antibodies - 0.2 mg/ml.ConclusionsThus, it has been shown in vitro that IgGs isolated from the serum of schizophrenia patients with or without DNA-hydrolyzing activity does not exhibit cytotoxic properties against the SH-SY5Y human neuroblastoma cell line. Support by Grant of RSF № 18-15-00053P.DisclosureNo significant relationships.

Twelve-Month Longitudinal Serology in SARS-CoV-2 Naïve and Experienced Vaccine Recipients and Unvaccinated COVID-19-Infected Individuals.

Longitudinal data comparing SARS-CoV-2 serology in individuals following infection and vaccination over 12 months are limited. This study compared the magnitude, decay, and variability in serum IgG, IgA, and neutralizing activity induced by natural infection (n = 218) or mRNA vaccination in SARS-CoV-2 naïve (n = 143) or experienced (n = 122) individuals over time using enzyme-linked immunosorbent assays and an in vitro virus neutralization assay. Serological responses were found to be highly variable after natural infection compared with vaccination but durable through 12 months. Antibody levels in vaccinated, SARS-CoV-2 naïve individuals peaked by 1 month then declined through 9 months, culminating in non-detectable SARS-CoV-2-specific serum IgA. Individuals with both infection and vaccination showed SARS-CoV-2-specific IgG and IgA levels that were more robust and slower to decline than the other groups; neutralizing activity remained highest in this group at 9 months past vaccination. These data reinforce the benefit of vaccination after SARS-CoV-2 recovery.