IgG Activity Research Articles

Extreme Diversity of IgGs Against Histones, DNA, and Myelin Basic Protein in the Cerebrospinal Fluid and Blood of Patients with Multiple Sclerosis.

It was recently shown that IgGs from sera of multiple sclerosis (MS) patients are active in the hydrolysis of DNA and myelin basic protein (MBP). We first analyzed the relative concentration of antibodies against five histones (H1, H2a, H2b, H3, and H4) in the cerebrospinal fluid (CSF) and serum of patients with MS. The relative concentrations of blood and CSF IgGs against histones and their activity in the hydrolysis of five histones varied greatly from patient to patient. However, all 28 IgG preparations were hydrolyzed from one to five histones. Relative activities and correlation coefficients among the activities of IgGs from serum and CSF in the hydrolysis of five histones (H1, H2a, H2b, H3, and H4), DNA, and MBP were calculated. It was shown that auto-IgGs from CSF and sera of MS patients are extremely heterogeneous in their affinity to histones, MBP, and DNA. The heterogeneity of IgG-abzymes hydrolyzing DNA, MBP, and histones from CSF and sera was also demonstrated using their isoelectrofocusing. The isofocusing profiles DNase, MBP-, and histone-hydrolyzing activities of IgGs may be very different for various individuals, but the total IgG subfractions with all their activities are distributed from pH 3 to 10.

High-throughput single-cell activity-based screening and sequencing of antibodies using droplet microfluidics.

Mining the antibody repertoire of plasma cells and plasmablasts could enable the discovery of useful antibodies for therapeutic or research purposes1. We present a method for high-throughput, single-cell screening of IgG-secreting primary cells to characterize antibody binding to soluble and membrane-bound antigens. CelliGO is a droplet microfluidics system that combines high-throughput screening for IgG activity, using fluorescence-based in-droplet single-cell bioassays2, with sequencing of paired antibody V genes, using in-droplet single-cell barcoded reverse transcription. We analyzed IgG repertoire diversity, clonal expansion and somatic hypermutation in cells from mice immunized with a vaccine target, a multifunctional enzyme or a membrane-bound cancer target. Immunization with these antigens yielded 100-1,000 IgG sequences per mouse. We generated 77 recombinant antibodies from the identified sequences and found that 93% recognized the soluble antigen and 14% the membrane antigen. The platform also allowed recovery of ~450-900 IgG sequences from ~2,200 IgG-secreting activated human memory B cells, activated ex vivo, demonstrating its versatility.

Effect of curcumin on laying performance, egg quality, endocrine hormones, and immune activity in heat-stressed hens

This study was conducted to evaluate the effect of curcumin on laying performance, egg quality, biochemical indicators, hormone levels, and immune activity in hens under heat stress. Hy-Line brown hens (280-day-old) were fed with 0, 100, 150, and 200 mg/kg of curcumin during a 42-D experiment. Compared with the control treatment, supplementation with 150 mg/kg of curcumin improved laying performance and egg quality by significantly increasing egg production, eggshell thickness, eggshell strength (P < 0.01), and albumen height (P < 0.05) while decreasing the feed-to-egg ratio. Antioxidant activity was improved by significantly increasing the activity of superoxide dismutase and glutathione peroxidase but decreasing malondialdehyde levels in serum (P < 0.05) and significantly increasing the levels of follicle-stimulating hormone, luteinizing hormone, estradiol, IgG, IgA, and complement C3 activity in serum (P < 0.05). These results indicated that supplemental 150 mg/kg curcumin can improve productive performance, antioxidant enzyme activity, and immune function in laying hens under the heat stress conditions applied in the present study.

IgG-Dependent Dismutation of Superoxide in Patients with Different Types of Multiple Sclerosis and Healthy Subjects.

This work is the first to demonstrate that class G immunoglobulins (IgGs) in patients with multiple sclerosis and healthy individuals have the ability to catalyze the dismutation reaction of the superoxide anion radical. Thus, superoxide dismutase (SOD) activity is an intrinsic property of antibodies, which is confirmed by a number of stringent criteria. SOD activity of IgGs in patients with multiple sclerosis statistically significantly exceeds such activity in healthy individuals by 2-4 times. Moreover, the maximum activity has been registered in patients with relapsing remitting multiple sclerosis. The kinetic characteristics of the SOD reaction of IgGs are several orders of magnitude lower than those for the SOD enzyme but do not differ between patients with multiple sclerosis and healthy individuals. Consequently, abzymes with SOD activity have a lower catalysis rate than that of the enzymes and form a stronger complex with the substrates. Inhibitory analysis showed that this activity is inhibited by classical metal-dependent SOD inhibitors. The activity of IgGs was inhibited by classical metal-dependent inhibitors EDTA and TETA (triethylenetetramine). Also, high catalase activity of IgGs was detected in these patients. We suggest that these abzymes help protect the body from oxidative stress.

The Immunological Organ Environment Dictates the Molecular and Cellular Pathways of Cytotoxic Antibody Activity

Cytotoxic immunoglobulin G antibodies are an essential component of therapeutic approaches aimed at depleting self-reactive or malignant cells. More recent evidence suggests that the tissue in which the target cell resides influences the underlying molecular and cellular pathways responsible for cytotoxic antibody activity. By studying cytotoxic IgG activity directed against natural killer cells in primary and secondary immunological organs, we show that distinct organ-specific effector pathways are responsible for target cell depletion. While in the bone marrow, the classical complement pathway and the high-affinity Fcγ-receptor I expressed on organ-resident macrophages were both involved in removing opsonized target cells; in the spleen and blood, all activating FcγRs but not the classical complement pathway were critical for target cell killing. Our study suggests that future strategies aimed at optimizing overall cytotoxic antibody activity may need to consider organ-specific pathways to achieve a maximal therapeutic effect.

Antibodies from the Sera of Multiple Sclerosis Patients Efficiently Hydrolyze Five Histones.

It is known that intranuclear histones can be pernicious after entering to the extracellular space. In addition, the immunization of animals with exogenous histones leads to systemic inflammatory and toxic reactions. Abzymes—autoantibodies with enzymatic activities—are the distinctive feature of autoimmune diseases and they can be especially dangerous to humans. Here, electrophoretically homogeneous IgGs were isolated from sera of patients with multiple sclerosis (MS) by chromatography on several affinity sorbents. We present evidence that sera of all MS patients contain autoantibodies against histones and 73% of IgGs purified from the sera of 59 MS patients efficiently hydrolyze from one to five histones: H1, H2a, H2b, H3, and H4. The relative average efficiency of the histones hydrolysis was ~3.9-fold higher than that for healthy donors. The relative average activity of IgGs depends on the type of MS and decreased approximately in the following order: debut of MS, secondary progressive multiple sclerosis, remitting multiple sclerosis, remittent progressive multiple sclerosis. Similar to proteolytic abzymes of patients with several autoimmune diseases, histone-hydrolyzing IgGs from MS patients were inhibited in the presence of specific inhibitors of serine and of metal-dependent proteases, but an unexpected significant inhibition of the activity by inhibitors of thiol-like and especially acidic proteases was observed. Since IgGs can efficiently hydrolyze histones, a negative role of abzymes in the development of MS cannot be excluded.

Application of volumetric absorptive microsampling (VAMS) to measure multidimensional anti-influenza IgG antibodies by the mPlex-Flu assay.

Introduction: Recently, volumetric absorptive microsampling (VAMS) has been used for accurate sampling of a fixed peripheral blood volume (10 µL) on a volumetric swab, and long-term sample storage. The mPlex-Flu assay is a novel, high-throughput assay that simultaneously measures the concentration of antibodies against the hemagglutinin (HA) proteins from multiple influenza virus strains with ≤5 µL of serum. Here we describe combining these two methods to measure multidimensional anti-influenza IgG activity in whole blood samples collected by a finger stick and VAMS, with correction for serum volume based on simultaneous hemoglobin measurement. Methods: We compared capillary blood samples obtained from a finger stick using a VAMS device with serum samples collected by traditional phlebotomy from 20 subjects, with the influenza antibody profiles measured by the mPlex-Flu assay. Results: We found that results with the two sampling methods were highly correlated within subjects and across all influenza strains (mean R 2 = 0.9470). Adjustment for serum volume, based on hemaglobin measurement, was used to estimate serum volume of samples and improved the accuracy. IgG measurements were stable over 3 weeks when VAMS samples were stored at room temperature or transported using a variety of shipping methods. Additionally, when volunteers performed finger-stick VAMS at-home by themselves, the comparison results of anti-HA antibody concentrations were highly consistent with sampling performed by study personnel on-site (R 2 = 0.9496). Conclusions: This novel approach can provide a simple, accurate, and low-cost means for monitoring the IgG anti-influenza HA antibody responses in large population studies and clinical trials.

Substrate specificity of IgGs with peroxidase and oxidoreductase activities from sera of patients with systemic lupus erythematosus and multiple sclerosis.

The analysis of IgGs to protect humans from oxidative stress through oxidation of harmful compounds was carried out. We have compared here for the first time peroxidase (in the presence of H2 O2 ) and oxidoreductase (in the absence of H2 O2 ) activities of IgGs from sera of healthy humans and patients with systemic lupus erythematosus (SLE) and multiple sclerosis (MS). In addition, substrate specificity of SLE and MS IgG preparations in the oxidation of different compounds was analyzed: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 3,3'-diaminobenzidine (DAB), homovanillic acid (HVA), o-phenylenediamine (OPD), α-naphthol, 3-amino-9-ethylcarbazole (AEC), p-hydroquinone (pHQ), and adrenaline. IgGs of healthy humans and SLE and MS patients oxidized DAB, ABTS, and OPD due to their peroxidase and oxidoreductase activities, while other compounds were substrates of IgGs only in the presence of H2 O2 : adrenaline was not oxidized by both activities of IgGs. The average SLE IgGs peroxidase activity increased statistically significant in comparison with abzymes from healthy humans in the order (-fold): OPD (1.2)< DAB (1.7)<α-naphtol (2.2)≤AEC (2.4)<ABTS (4.5)<5-ASA (10.6), while with oxidoreductase activity: OPD (1.8)≤DAB (2.1-fold)<ABTS (5.0). Only HVA was oxidized by IgGs with peroxidase activity of healthy donors faster than by SLE (1.3-fold) and MS abzymes (2.4-fold). In the oxidation of several substrates, only three IgGs of MS patients were used. The data speak of a tendency to increase the peroxidase and oxidoreductase activities of MS IgGs in comparison with healthy donors, but to a lesser extent: OPD (1.1 to 1.2-fold)≤ABTS (1.2 to 1.8-fold). It was shown that development of SLE and MS leads to increase in peroxidase and oxidoreductase activities of IgGs toward most of classical substrates. Thus, abzymes can serve as an additional factor of reactive oxygen species detoxification protecting of patients with SLE and MS from some harmful compounds somewhat better than healthy peoples.

Comparison of Serum IgG Concentration, Total Protein, Glutaraldehyde Coagulation 2 Test and Gamma Glutamyl Transferase Activity in Neonatal Foals

The purpose of the present study was to detect the passive transfer status in healthy neonatal foals by comparing serum immunoglobulin G (sIgG) concentration, serum total protein (STP), gamma glutamyl transferase (GGT) activity and glutaraldehyde test (GCT) duration. Fifteen (15) neonatal foals (0-15 days old)’ blood samples were collected before suckling (day 0), 12th hour(hr), 24th hr (1st day), 7th and 15th days. Serum IgG and STP activity significantly increased after the 12th hr. Conversely, serum GCT duration significantly decreased in neonatal foals after the 12th hr. The results of the present study was shown that measurements of sIgG, STP concentration and GCT duration are useful to detect Failure of Passive Transport (FPT) in neonatal foals. While GCT and STP provide a simple and inexpensive field test, serum GGT measurement is not a beneficial test to determine colostrum intake in newborn foals.

Antibody Reactivity to Merozoite Antigens in Ghanaian Adults Correlates With Growth Inhibitory Activity Against Plasmodium falciparum in Culture.

Background Plasmodium falciparum uses a repertoire of merozoite-stage proteins for invasion of erythrocytes. Antibodies against some of these proteins halt the replication cycle of the parasite by preventing erythrocyte invasion and are implicated as contributors to protective immunity against malaria.MethodsWe assayed antibody reactivity against a panel of 9 recombinant antigens based on erythrocyte-binding antigen (EBA) and reticulocyte-like homolog (Rh) proteins in plasma from children with malaria and healthy adults residing in 3 endemic areas in Ghana using enzyme-linked immunosorbent assay. Purified immunoglobulin (Ig)G from adult plasma samples was also tested for invasion inhibition against 7 different P falciparum culture lines, including clinical isolates.ResultsAntibodies against the antigens increased in an age-dependent manner in children. Breadth of reactivity to the different antigens was strongly associated with in vitro parasite growth inhibitory activity of IgG purified from the adults. The strongest predictors of breadth of antibody reactivity were age and transmission intensity, and a combination of reactivities to Rh2, Rh4, and Rh5 correlated strongly with invasion inhibition.ConclusionsGrowth inhibitory activity was significantly associated with breadth of antibody reactivity to merozoite antigens, encouraging the prospect of a multicomponent blood-stage vaccine.

433 Pemphigus vulgaris patient disease severity correlates with in vitro assessments of desmosomal function

Pemphigus vulgaris (PV) is an autoimmune bullous skin disease characterized by severe epidermal blistering and mucous membrane erosions. PV is caused by antibodies directed against the desmosomal cadherin desmoglein 3 (Dsg3), and in cases involving the skin, both Dsg3 and Dsg1. PV can be assessed clinically using the Pemphigus Disease Area Index (PDAI) and using an ELISA for Dsg IgG titers in patient sera. In vitro, PV IgG activity can be investigated by incubating normal human keratinocytes with PV patient IgG and monitoring changes in desmosomal protein organization and overall strength of cell-cell adhesion using a dispase-based cell-cell dissociation assay. However, the relationship between clinical PV assessments and in vitro activity of patient IgG have not been reported. In the present study, we compared the relationship between the in vitro pathogenicity of PV IgG from 23 patients to their PDAI score and ELISA titers. Overall, Dsg1 ELISA values showed a stronger correlation with PDAI scores (p<0.01) when compared to Dsg3 ELISA (p<0.02). However, the sum of Dsg3 and Dsg1 ELISA values exhibited a highly significant correlation to PDAI (p<0.0005). In vitro, treatment of keratinocytes with patient IgG resulted in a range of alterations in desmosomal protein organization that included Dsg3 clustering, the formation of linear array-like structures, and endocytosis of Dsg3-PV IgG complexes. Interestingly, the loss of cell-cell adhesion strength as assessed using in vitro dispase cell dissociation assays exhibited a positive correlation with Dsg3 ELISA titers (p<0.005), supporting the validity of the dispase assay as a measure of PV pathogenicity . These findings confirm the association of Dsg ELISA values with PDAI and establish a relationship between Dsg IgG titers in patients and loss of adhesion in cultured keratinocytes.

Effect of Selenium and Bee Pollen Against Immunotoxicity and Hepatotoxicity Induced by Cadmium in Male Albino Rats.

Cadmium is a toxic naturally occurring element that affects numerous organ systems in humans, the present study was designed to study the role of bee pollen and selenium against cadmium chloride induced immunotoxicity and Hepatotoxicity in male albino rats. Forty (40) male albino rats were used for the experiment. Group I was intraperitoneal (i.p.) Injected with saline solution, G2 (i.p.) Injected with CdCl2 (1 mg/kg b.w.), G3 were (i.p.) Injected with CdCl2 (1 mg/kg b.w.) and then receive selenium (i.p.) Injection at a dose of (0.5 mg/kg/day). G4 (i.p.) Injected with CdCl2 (1 mg/kg b.w. day by day) and then received bee pollen orally at a dose of (10 g/kg/day). Animals were exposed to treatment once daily for 10weeks. After the last day of treatment, animals were sacrificed and blood samples collected for hematological analysis and serum separated for serum liver enzymes analysis and the liver separated for oxidative stress analysis. Results obtained in this present study revealed a significant increased at (p>0.05) in WBCs, Monocyte , Lymphocyte , Granulocyte and The activities of IgG and IgM, aspartate aminotransferase (AST), alanine transferase (ALT) ,alkaline phosphatase (ALP), (Total- Direct) bilirubin and Malondialdehyde (MAD), while showed a significant decreased at (p>0.05) in albumin and protein, Glutathione (GSH), Superoxide dismutase (SOD) and Catalase (CAT) in group treated with CdCl2 only when compared with normal group. However, Effects of bee pollen and selenium on immunotoxicity and hepatic injury due to cadmium-induced oxidative stress revealed a significant decreased at (p>0.05) in WBCs, Monocyte, Granulocyte and The activities of IgG except Lymphocyte and IgM are not affected also aspartate aminotransferase(AST), alanine transferase (ALT) ,alkaline phosphatase (ALP), (Total- Direct) bilirubin and Malondialdehyde (MAD) showed a significant decreased at (p>0.05), while Total protein, Albumin, Glutathione (GSH), Superoxide dismutase (SOD) and Catalase (CAT) showed a significant increased at (p>0.05) when compared with control group. It is concluded that the bee pollen and selenium have antioxidant properties

Serum Immunoglobulin Levels and Complement Function of Tannery Workers in Bangladesh.

Background.Occupational exposures to chromium (Cr), which can have adverse effects on immune function, have not yet been extensively investigated. Hexavalent chromium (Cr (VI)), used in mineral tanning processes, poses a threat to the health of workers in the leather tanning industry.Objectives.The aim of the present study was to evaluate the effects of long-term Cr exposure on the physical health and immunological parameters of male tannery workers in Bangladesh compared with a control group.Methods.A health examination was performed with tannery workers (N=195) and control subjects (N=125) by physicians, demographic data were recorded in questionnaires and peripheral blood samples were collected. Serum Cr levels were analyzed by an atomic absorption spectrophotometer (AAS), immunoglobulin (Ig)G, IgA, and complement components C3 and C4 were determined by nephelometry, IgE was measured by sandwich enzyme-linked immunosorbent assay and complement function was assayed by bactericidal activity.Results.The mean duration of work exposure for the tanners was 9.4±7.1 years. Their body mass index (21.8±3.0 kg/m2), was not significantly different from the controls (22.7±3.2 kg/m2). The mean serum level of Cr in 30 long-term exposed tannery workers (26.97±21.11 μg/dL) was significantly higher than that of 30 randomly selected control subjects (7.38±6.81 μg/dL). The tannery workers had rough skin, rashes, itchy and decolorized skin, allergic diseases and respiratory illness, and had significantly lower levels of serum IgG, IgA, C3 and C4, but significantly higher levels of IgE than the controls. IgG, IgA and C3 levels were all inversely associated with Cr, while IgG, IgE and bactericidal activity showed an inverse correlation with duration of exposure.Conclusions.The results of the present study suggest that chronic exposure to Cr is associated with impaired immune function in male tannery workers.Participant Consent.ObtainedEthics Approval.The present study was approved by the Ethical Review Committee of the faculty of Biological Sciences, University of Dhaka, Bangladesh.Competing Interests.The authors declare no competing financial interests.

Pure Red Cell Aplasia Secondary to Parvovirus B19 Infection in HIV Positive Patients. Clinical and Seroepidemiological Description and Observations in A Third Hospital Level In Colombia

Objective: Describe the clinical and seroepidemiological characteristics and the impact on morbidity and mortality and health costs of patients infected with HIV and red cell aplasia and positive serology for Parvovirus B 19. Methodology: Descriptive and retrospective study, of the clinical and seroepidemiological characteristics of cases of aplasia of the red series without affecting hematimetric indices in HIV positive patients with positive serology to Parvovirus B19, were descripted in an hospitalization service in the period from April 2016 to April 2017. Serum samples from the 16 patients enrolled for the study were analyzed by IgG and IgM type antibodies using the enzyme immunoassay technique. Other causes of anemia, such as: iron-deficiency anemia, invasive fungal infection were ruled out. Results: A total of 16 cases were documented, 11 men (69%) and 5 women (31%) with an average age of 40.7 and 44.4 years respectively, 5 of the 16 patients (31.25%) had positive IgM levels (distributed among 3 men and 2 women) without IgG activity documented in the same sample and 4 of these 5 patients were without treatment for their HIV (80%), none of the patients received regular treatment for HIV. The average in grams per deciliter of hemoglobin and hematocrit at the time of sampling was 8.92 g / dl and 28.6 g / dl respectively, the average of CD4 cell count was 115 for the male population and 187.2 for the female population, the average viral load was 515,483 and 369,390 copies / ml for men and women respectively. No patient received adjuvant treatment directed at the pure red anemia demonstrated. Conclusion: Persistent parvovirus B19 infections in human immunodeficiency virus type 1 infected patients have been reported. The two viruses could share common target cells. The co-infection by Parvovirus B19 is associated with longer days of hospital stay, costs and complications such as nosocomial infections and need of poly transfusions.

Determination of Levels of IgE and IgG and the Activity of Complement Comparatively in Blood and Lymph in the Experimental Arthus and Overy Phenomenon

The aim of investigation was the determination of the levels of IgE, IgG and complement activity in the blood and lymph in the experimental Arthus and Overy phenomenon. Experiments were carried out on 27 chinchilla rabbits (weight 2.5-3kg) in three series. To reproduce the Arthus phenomenon, rabbits were sensitized by subcutaneous administration of 1 ml of horse serum to the scapular region every 5 days; after the fifth injection in the injection area of horse serum the necrosis was observed. To obtain the Overy phenomenon, a resolving dose of horse serum was injected subcutaneously in a sensitized animal, and an Evans blue was introduced into the auricular vein. In this case, the injection area is colored blue. The blood necessary for the experiment was taken from the marginal auricular vein of the rabbit, and lymph – from the thoracic lymphatic duct. The levels of IgE and IgG and the activity of the complement comparatively in the blood and lymph in the experimental Arthus and Overy phenomenon were studied. The experiments were carried out on 27 rabbits of the «Chinchilla» breed in two series. The studied parameters of IgE and IgG and complement activity in blood and lymph of intact animals served as control. The results of the study showed that the level of IgG in the Arthus phenomenon increases and IgE decreases. While at the Overy phenomenon, on the contrary, the level of IgE increases and the level of IgG decreases. The titer of complement in immune complex reactions is sharply reduced; it indicates the involvement of complement with IgG elimination of the allergen.

Prognostic Impact of Germ-Line FCGR2A (H131R), FCGR3A (F158V), and FCGR2B (I232T) Single Nucleotide Polymorphisms in Lymphoma Patients Treated with Obinutuzumab or Rituximab in Combination with Chemotherapy: Results from the Phase III GALLIUM and GOYA Clinical Trials

Prognostic Impact of Germ-Line FCGR2A (H131R), FCGR3A (F158V), and FCGR2B (I232T) Single Nucleotide Polymorphisms in Lymphoma Patients Treated with Obinutuzumab or Rituximab in Combination with Chemotherapy: Results from the Phase III GALLIUM and GOYA Clinical Trials

Pentraxins and Fc Receptor-Mediated Immune Responses.

C-reactive protein (CRP) is a member of the pentraxin family of proteins. These proteins are highly conserved over the course of evolution being present as far back as 250 million years ago. Mammalian pentraxins are characterized by the presence of five identical non-covalently linked subunits. Each subunit has a structurally conserved site for calcium-dependent ligand binding. The biological activities of the pentraxins established over many years include the ability to mediate opsonization for phagocytosis and complement activation. Pentraxins have an important role in protection from infection from pathogenic bacteria, and regulation of the inflammatory response. It was recognized early on that some of these functions are mediated by activation of the classical complement pathway through C1q. However, experimental evidence suggested that cellular receptors for pentraxins also play a role in phagocytosis. More recent experimental evidence indicates a direct link between pentraxins and Fc receptors. The Fc receptors were first identified as the major receptors for immunoglobulins. The avidity of the interaction between IgG complexes and Fc receptors is greatly enhanced when multivalent ligands interact with the IgG binding sites and activation of signaling pathways requires Fc receptor crosslinking. Human pentraxins bind and activate human and mouse IgG receptors, FcγRI and FcγRII, and the human IgA receptor, FcαRI. The affinities of the interactions between Fc receptors and pentraxins in solution and on cell surfaces are similar to antibody binding to low affinity Fc receptors. Crystallographic and mutagenesis studies have defined the structural features of these interactions and determined the stoichiometry of binding as one-to-one. Pentraxin aggregation or binding to multivalent ligands increases the avidity of binding and results in activation of these receptors for phagocytosis and cytokine synthesis. This review will discuss the structural and functional characteristics of pentraxin Fc receptor interactions and their implications for host defense and inflammation.

Co-stimulation With TLR7 Agonist Imiquimod and Inactivated Influenza Virus Particles Promotes Mouse B Cell Activation, Differentiation, and Accelerated Antigen Specific Antibody Production.

Current influenza vaccines have relatively low effectiveness, especially against antigenically drifted strains, the effectiveness is even lower in the elderly and immunosuppressed individuals. We have previously shown in a randomized clinical trial that the topical application of a toll-like receptor 7 agonist, imiquimod, just before intradermal influenza vaccine could expedite and augment antibody response, including to antigenically-drifted strains. However, the mechanism of this vaccine and imiquimod combination approach is poorly understood. Here, we demonstrated that imiquimod alone directly activated purified mouse peritoneal B cells. When combined with inactivated H1N1/415742Md influenza virus particle (VP) as vaccine, co-stimulation of mouse peritoneal B cells in vitro induced stronger activation, proliferation, and production of virus-antigen specific IgM and IgG. Intraperitoneal injection of a combination of VP and imiquimod (VCI) was associated with an increased number of activated B cells with enhanced expression of CD86 in the mesenteric draining lymph nodes (mesLN) and the spleen at 18 h after injection. Three days after immunization with VCI, mouse spleen showed significantly more IgM and IgG secreting cells upon in vitro re-stimulation with inactivated virus, mouse sera were detected with viral neutralizing antibody. Transfer of these spleen B cells to naïve mice improved survival after lethal dose of H1N1/415742Md challenge. More importantly, the functional response of VCI-induced B cell activation was demonstrated by early challenge with a lethal dose of H1N1/415742Md influenza virus at 3 days after immunization. The spleen and mediastinal lymph nodes (mdLN) in mice immunized with VCI had germinal center formation, and significantly higher number of plasmablasts, plasma cells, and virus-antigen specific IgM and IgG secreting cells at only 3–4 days post virus challenge, compared with those of mice that have received imiquimod, inactivated virus alone or PBS. Serum virus-specific IgG2a, IgG2b, and IgG1 and bronchoalveolar lavage fluid (BALF) virus-specific IgA at 3 or 4 days post challenge were significantly higher in mice immunized with VCI, which had significantly reduced lung viral load and 100% survival. These findings suggested that imiquimod accelerates the vaccine-induced antibody production via inducing rapid differentiation of naïve B cells into antigen-specific antibody producing cells.

Screening of more than 2000 Hungarian healthcare workers' anti-measles antibody level: results and possible population-level consequences.

Due to the European measles epidemic and the increased number of imported cases, it can be theorised that the risk of exposure among Hungarian healthcare workers (HCWs) has increased. In 2017, the increased measles circulation in the region led to the emergence of smaller local and hospital epidemics. Therefore, our objective was to determine the herd immunity in the high-risk group of HCWs. A hospital-based study of detecting anti-measles IgG activity was performed in 2017 and included 2167 employees of the Military Medical Centre (Hungary). The screening of HCWs presented a good general seropositivity (90.6%). The highest seroprevalence value (99.1%) was found in the age group of 60 years or older. The lowest number of seropositive individuals was seen in the 41-45 years (86.2%) age group, indicating a significant herd immunity gap between groups. Regarding the Hungarian data, there might be gaps in the seroprevalence of the analysed HCWs, implying that susceptible HCWs may generate healthcare-associated infections. This study suggests that despite the extensive vaccination and high vaccine coverage, it is still important to monitor the level of protective antibodies in HCWs, or in a representative group of the whole population of Hungary, and possibly in other countries as well.

L-Leucine influx through Slc7a5 regulates inflammatory responses of human B cells via mammalian target of rapamycin complex 1 signaling

Objectives: Increasing evidence has revealed the close correlation between immune cell functions and their intracellular metabolism. Mammalian target of rapamycin complex 1 (mTORC1) is the important metabolism-modulating signal that regulates cellular activities. In certain types of cell, it is known that mTORC1 activation depends on influx of l-leucine through an amino acid transporter, Slc7a5. In B cells, however, the expression and the role of Slc7a5 have never been investigated.Methods: CD19+ B cells were obtained from peripheral blood of healthy adults and stimulated by a toll-like receptor 9 ligand, CpG oligodeoxynucleotides. The expression of Slc7a5 and l-leucine uptake were evaluated by RT-PCR, flow cytometry and radioisotope assay. Then the effect of Slc7a5 inhibition on mTORC1 activity, plasmablast differentiation and production of IgG and inflammatory cytokines were analyzed.Results: CpG stimulation significantly induced the expression of Slc7a5 in B cells, resulting in l-leucine influx. Furthermore, inhibition of Slc7a5 abrogated mTORC1 activation, plasmablast differentiation, and production of IgG and inflammatory cytokines in CpG-stimulated B cells.Conclusion: l-leucine influx through Slc7a5 critically regulates mTORC1 activity and the immunological responses of human B cells. Slc7a5-mTORC1 pathway may provide a novel therapeutic strategy for autoimmune diseases.