Total Immunoglobulin G Concentration Research Articles

An engineered immunomodulatory IgG1 Fc suppresses autoimmune inflammation through pathways shared with i.v. immunoglobulin.

Immunoglobulin G (IgG) antibodies in the form of high-dose intravenous immunoglobulin (IVIG) exert immunomodulatory activity and are used in this capacity to treat inflammatory and autoimmune diseases. Reductionist approaches have revealed that terminal sialylation of the single asparagine-linked (N-linked) glycan at position 297 of the IgG1 Fc bestows antiinflammatory activity, which can be recapitulated by introduction of an F241A point mutation in the IgG1 Fc (FcF241A). Here, we examined the antiinflammatory activity of CHO-K1 cell-produced FcF241A in vivo in models of autoimmune inflammation and found it to be independent of sialylation. Intriguingly, sialylation markedly improved the half-life and bioavailability of FcF241A via impaired interaction with the asialoglycoprotein receptor ASGPR. Further, FcF241A suppressed inflammation through the same molecular pathways as IVIG and sialylated IgG1 Fc and required the C-type lectin SIGN-R1 in vivo. This contrasted with FcAbdeg (efgartigimod), an engineered IgG1 Fc with enhanced neonatal Fc receptor (FcRn) binding, which reduced total serum IgG concentrations, independent of SIGN-R1. When coadministered, FcF241A and FcAbdeg exhibited combinatorial antiinflammatory activity. Together, these results demonstrated that the antiinflammatory activity of FcF241A requires SIGN-R1, similarly to that of high-dose IVIG and sialylated IgG1, and can be used in combination with other antiinflammatory therapeutics that rely on divergent pathways, including FcAbdeg.

Population pharmacokinetics of immunoglobulin G after intravenous, subcutaneous, or hyaluronidase-facilitated subcutaneous administration in immunoglobulin-naive patients with primary immunodeficiencies

Immunoglobulin G (IgG) replacement therapy is the standard of care for patients with primary immunodeficiencies with antibody deficiencies. Intravenous (IVIG), subcutaneous (SCIG), and hyaluronidase-facilitated subcutaneous immunoglobulin (fSCIG) therapies differ in their pharmacokinetic (PK) profiles, administration routes, and dosing regimens. Information on use of subcutaneous therapy in IgG treatment-naive patients is limited. This study used population pharmacokinetic (popPK) model-based simulations to characterize IgG PKs in IgG-naive patients with varying disease severity across several IVIG, SCIG, and fSCIG dosing regimens. An integrated popPK model, developed and validated using data from eight clinical trials, was utilized to simulate scenarios that varied by therapy, loading regimen, maintenance dose (equivalent to 400, 600, or 800 mg/kg every 4 weeks [Q4W]), and baseline endogenous total IgG concentration (1.5 or 4.0 g/L). Simulations were performed for age groups of 2–<6, 6–<12, 12–<18, and ≥18 years. Steady-state serum trough IgG concentrations (Cmin,ss), proportion of patients achieving Cmin,ss ≥ 7 g/L, and days taken to reach this threshold were summarized. SCIG provided greater mean Cmin,ss values than IVIG and fSCIG for any scenario. Across all therapies, Cmin,ss tended to increase with age, dose, and endogenous concentration. Although the findings are model-based and not a summarization of real-world observations, doses ≥ 800 mg/kg Q4W with corresponding loading regimens are likely to be clinically appropriate for achieving target IgG concentrations in treatment-naive patients in a timely manner, especially at low endogenous starting concentrations. Therapy-specific dose adjustment based on baseline endogenous IgG concentration, clinical status, and patient characteristics may be warranted.

Total and pathogen-specific serum Immunoglobulin G concentrations in neonatal beef calves, Part 1: Risk factors.

Maternal antibodies, delivered to the calf via colostrum, are crucial to prevent calfhood diseases and death. However, knowledge regarding the factors influencing this transfer of total and specific Immunoglobulin G (IgG) against common enteric and respiratory disease pathogens under current production conditions is sparse. The objectives of this study were to determine risk factors influencing total and pathogen-specific immunoglobulin G (IgG) concentrations against Escherichia coli (E. coli), bovine Rotavirus (BRoV), Cryptosporidium parvum (C. parvum), Bovine Viral Diarrhea Virus type 1 and 2 (BVDV), Parainfluenza Virus Type 3 (PI-3), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Herpesvirus type 1 (BHV-1) in the serum of newborn beef calves. A total of 420 serum samples were collected from 1- to 7-day-old beef calves born on 6 farms in Alberta, Canada. Samples were analyzed by radial immunodiffusion for total IgG concentration and by enzyme-linked immunosorbent assays for pathogen-specific IgG concentrations against E. coli, BRoV, C. parvum, BVDV, PI-3, BRSV, and BHV-1. Multivariable multilevel linear and logistic regression models were built to evaluate dam- and calf-level risk factors associated with total and pathogen-specific IgG concentrations, failed transfer of passive immunity (FTPI; serum IgG < 10g/L), and inadequate transfer of passive immunity (ITPI; serum IgG < 24g/L). Farm was included as a random effect in all models to account for clustering at the herd level. Of the 420 calves included in this study, 5% (n=20) and 18% (n=75) of calves had FTPI and ITPI, respectively. Receiving colostrum intervention (i.e., being fed colostrum or colostrum product by either bottle or tube) was the most consistent risk factor for low total IgG concentration and significantly increased the odds of FTPI (Odds ratio (OR): 6.1, 95% CI: 2.0-18.9) and ITPI (OR: 4.8, 95% CI: 2.1-10.8). Calves born to cows consistently had higher pathogen-specific IgG concentrations (P<0.0001), compared to calves born from heifers, and calves born to vaccinated dams had significantly higher BRoV, BVDV, and BHV-1-specific IgG concentrations. Interestingly, E.coli-specific IgG concentrations were associated with dam vaccination only in cows but not in heifers, which was likely due to differing vaccination strategies used. This study highlights the need to review and refine protocols with respect to dam vaccination and colostrum intervention on cow-calf operations.

Total and pathogen-specific serum Immunoglobulin G concentrations in neonatal beef calves, Part 2: Associations with health and growth.

The association of poor transfer of passive immunity (TPI) with negative health outcomes is extensively researched in dairy calves. However, few field studies have examined the effect of total and particularly pathogen-specific Immunoglobulin G (IgG) concentrations on pre-weaning health and growth of beef calves. Hence, the objective of this study was to determine the association of total and pathogen-specific IgG concentrations against selected pathogens associated with neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) and the odds of pre-weaning treatments, mortality, and the growth of newborn beef calves. A total of 420 serum samples from 1- to 7-day old beef calves born on 6 farms in Alberta, Canada, were available for this observational study. Serum samples were analyzed by radial immunodiffusion for total IgG concentration and by enzyme-linked immunosorbent assays for pathogen-specific IgG concentrations against Escherichia coli (E. coli), bovine Rotavirus (BRoV), Cryptosporidium parvum (C. parvum), Bovine Viral Diarrhea Virus (BVDV), Parainfluenza Virus Type 3 (PI-3), Bovine Respiratory Syncytial Virus (BRSV), and Bovine Herpesvirus Type 1 (BHV-1). Data about the individual dam- and calf-level risk factors, calf treatments, mortality, and birth and weaning weights were collected. Multivariable multilevel logistic and linear regression models were built to evaluate the association of total and pathogen-specific IgG concentrations with the odds of mortality and average daily gain (ADG), respectively, while their association with the odds of pre-weaning treatment was established by univariable logistic regression analysis. The odds of calves with IgG concentrations <10g/L of getting treated (OR 7.9, 95 % CI 2.7-23.7) and dying (OR: 18.5, 95 % CI: 3.7-93.4) were higher than for their counterparts (P<0.0001). Calves with IgG concentrations <24g/L also had higher odds of dying (OR: 10.1, 95 % CI: 2.6-40.2) and had lower ADG (-0.09kg, SE: 0.03, P<0.002) than calves with IgG concentrations ≥24g/L. Higher BVDV-specific IgG concentration was protective against mortality (OR: 0.97, 95 % CI: 0.96-0.99, P<0.001). This study highlights the negative association of inadequate TPI with health and growth of beef calves and thus, the need to refine protocols for dam vaccination and colostrum intervention in cow-calf operations to meet these higher IgG targets.

Relationship between Body Composition and Serum Immunoglobulin Concentrations after Administration of Intravenous Immune Globulin–Preclinical and Clinical Evidence

The purpose of this study was to investigate the effect of obesity on immunoglobulin G (IgG) pharmacokinetics in a rat model of obesity, and to collect clinical evidence for an association between the body composition and intravenous immune globulin (IVIG) pharmacokinetic parameters in humans. In a preclinical study, pharmacokinetics of human IgG was evaluated after intravenous (IV) and subcutaneous (SC) delivery to obese and lean rats (n = 6 in each group). Serial serum samples were analyzed using an ELISA. The animal body composition was assessed using computer tomography. Patients with primary immunodeficiency currently managed with IVIG, and at a steady state, were enrolled in the clinical study (n = 8). Serum immune globulin (Ig) concentrations were measured at baseline and immediately after the administration of two consecutive treatments, with an additional measurement at two weeks after the first administration. In addition to the patient demographic and clinical characteristics, body composition was measured using bioelectrical impedance analysis. The pharmacokinetics of human IgG was significantly different between the obese and lean rats after both the IV and SC administration of 0.5 g/kg. Furthermore, a significant difference in endogenous rat IgG was observed between the two strains. In the human study, total serum IgG and subtype (IgG1, IgG2, IgG3, IgG4) half-life negatively correlated with the body mass index and fat mass. The mean change in the total serum IgG concentration was significantly correlated to body mass index and fat mass. The results of the studies corroborated one another. In the animal study, most pharmacokinetic parameters of human IgG following IV and SC administration were significantly affected by obesity and changes in the body composition. In the clinical study, the mean serum IgG change after the IVIG administration strongly correlated to the BMI and body fat mass. Future studies are needed to establish the outcomes achieved with more frequent dosing in obese individuals with primary immunodeficiency.

Immunogenicity of the Currently Recommended Pneumococcal Vaccination Schedule in Patients with Chronic Lymphocytic Leukaemia

Background Patients with chronic lymphocytic leukemia (CLL) are at increased risk of both invasive pneumococcal disease (IPD) and community acquired pneumonia (CAP) caused by Streptococcus pneumoniae. Therefore, international guidelines recommend pneumococcal vaccination for all CLL patients, preferably before initiation of treatment. The vaccination schedule recommended in the European Conference on Infections in Leukaemia (ECIL) 7 guideline consists of Prevnar13®, a 13-valent pneumococcal conjugated vaccine (PCV13) followed 2 months later by Pneumovax23®, a 23-valent polysaccharide vaccine (PPSV23). However, the immunogenicity of this sequential pneumococcal vaccination schedule in CLL patients is unknown. The aim of this study is to assess the immunogenicity of PCV13 followed by PPSV23 in untreated and treated CLL patients, as CLL treatment has been shown to be a major determinant of COVID-19 vaccine immunogenicity. Methods We quantified pneumococcal immunoglobulin G (IgG) concentrations to 5 pneumococcal serotypes shared across both vaccines (6B, 9V, 14, 19F, 23F) and 4 serotypes unique to PPSV23 (8, 15B, 20, 33F) before and 4-8 weeks after vaccination using a validated multiplex immunoassay, Luminex®. The primary outcome was the serologic response rate (SRR), defined as a ≥4-fold increase in ≥70% of the serotype-specific anti-pneumococcal IgGs. Secondary outcome was serologic protection, defined as an antibody concentration of ≥1.3 mcg/ml for ≥70% of all measured serotypes, in accordance with the definition by the American Academy of Allergy, Asthma & Immunology. Additional secondary outcomes were serotype-specific serologic protection and IgG level dynamics. Results We included 113 CLL patients (mean age 66 years; 39/113 female) in one academic and six teaching hospitals in the Netherlands. All completed the vaccination and measurement schedule. Median time since CLL diagnosis was 3.6 years. Of the 113 patients 33 had previously received CLL treatment, including rituximab (22 patients), cytotoxic chemotherapy (11), ibrutinib (10) and/or venetoclax (7). Seven patients received intravenous immunoglobulin prior to the vaccinations, while 6 received this during the vaccination scheme. The SRR was 11.5% (15% in untreated and 3% in treated patients) (Table 1). A statistically significant increase in all serotype-specific antibody concentrations was observed after vaccination (p <0.001) (Figure 1). The immunogenicity varied per serotype: the percentage of patients mounting a 4-fold increase was lowest for serotype 20 (16%) and highest for serotype 9V (40%). The serotype-specific anti-pneumococcal IgGs after vaccination were all significantly lower in treated than in previously untreated patients. Nevertheless, treatment status was not statistically significant associated with the SRR. Total IgG concentration prior to vaccination was the only evaluated factor associated with the SRR (OR 5.69; p = 0.008). Serologic protection increased from 1.8% before vaccination to 10.6% after both vaccinations (13.8% in untreated and 3% in treated patients). Serotype-specific protection was highest for serotype 14 and 33F (43.4% of patients obtained a concentration of ≥1.3 mcg/ml) and lowest for serotype 6B (16.8%). Conclusion The serologic response to combined PCV13 and PPSV23 vaccination is impaired in previously treated CLL patients as well as in treatment-naive patients, a contrast with COVID-19 vaccination. These findings emphasize the importance of further investigation into the pneumococcal vaccination response in CLL patients. Since patients with CLL are insufficiently protected after a single dose of PCV13, research should focus on multi-dose PCV schedules with the currently available higher valent T cell dependent conjugate vaccines. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Pharmacokinetic / Pharmacodynamic (PK/PD) Simulations Guide Selection of the Dose for Administration of Efgartigimod Subcutaneously in a Phase 3 Clinical Trial in Patients with Primary Immune Thrombocytopenia

IntroductionEfgartigimod (ARGX-113) is a human IgG1-derived Fc fragment that binds with high affinity to FcRn in a pH dependent way, resulting in a blockade of FcRn-mediated recycling of IgGs. This leads to rapid degradation of all IgGs, including disease associated autoantibodies.The efficacy, safety, tolerability, and pharmacokinetic (PK) and pharmacodynamic (PD) profile of intravenously (IV) administered efgartigimod have been assessed during a Phase 1 study in healthy subjects (Ulrichts P. JCI. 2018;128), Phase 2 studies in patients with Myasthenia gravis (MG) (Howard JF. Neurol. 2019;92) and Immune Thrombocytopenia (ITP) (Newland AC. Am J Hematol. 2020;95:178-187), and a Phase 3 study in MG (Howard JF. Lancet Neurol. 2021;20). These studies have demonstrated that a dose of 10 mg/kg efgartigimod, administered in four weekly (qw) IV infusions, achieves close to maximal immunoglobulin G (IgG) reduction and a significant reduction of pathogenic autoantibodies in patients with ITP and MG. Furthermore, this dose was well-tolerated in all populations. Based on the results of the Phase 2 study in Primary ITP, a Phase 3 study was designed for IV administration in patients with persistent or chronic primary ITP (ADVANCE NCT04188379).To allow for a convenient SC administration of efgartigimod at a dose that achieves a similar PD effect comparable to IV 10 mg/kg, a co-formulation with rHuPH20 SC was developed (recombinant human hyaluronidase PH20, an enzyme used to increase the dispersion and absorption of co-administered substances when administered subcutaneously). Here we describe the dose selection process for the SC dose to be used in a Phase 3 study of patients with persistent or chronic ITP.MethodsPK and PD data from a Phase 1 study, including 32 healthy adult male subjects receiving 750 mg, 1250 mg, 1750 mg, or 10 mg/kg single SC injections of efgartigimod co-mixed with rHuPH20 (8 subjects/dose group), were used for a PK/PD analysis to predict the efgartigimod PH20 SC dose that would result in a similar PD effect compared to the benchmark dose from previous studies of 10 mg/kg IV (1 hour infusion and body weight of 70 kg).ResultsWeekly SC administration of 1000 mg efgartigimod co-mixed with 2000 U/mL rHuPH20 was predicted to result in comparable maximum total IgG reduction after the 4 th SC injection (days 22-29) as after the 4 th IV infusion of 10 mg/kg administered qw (Figure 1). Additionally, the area under the curve for total IgG concentration after the 4th dose (days 22-29) and trough IgG reduction (measured prior to dose on day 29) were predicted to be comparable between weekly 1000 mg SC and the weekly 10 mg/kg IV benchmark dose.No statistically significant effect of body weight on the PK and PD of efgartigimod PH20 SC was found.DiscussionThese results informed the weekly SC dose administration schedule in ADVANCE SC, a Phase 3, multicenter, randomized, double-blinded, placebo-controlled trial (NCT04687072) for evaluation of efficacy and safety of efgartigimod PH20 SC in adults with persistent or chronic primary ITP. Efgartigimod PH20 SC or placebo PH20 SC will be given weekly on visits 1-4 and then either weekly or every other week from visits 5 to 16, as determined by platelet counts. The frequency of administration will remain unchanged for the last 7 weeks (visits 17 to 24) to evaluate the sustainable platelet count improvement as the primary objective. Secondary objectives include extent of disease control (overall platelet count response, use of rescue treatment, and changes in concurrent ITP therapy), bleeding events, and quality of life assessments. ADVANCE SC recruitment is currently ongoing across approximately 70 sites in Asia-Pacific, Europe, Japan, Latin America, Middle East, Africa, and USA. [Display omitted] DisclosuresGhanima: Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Principia: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Bayer: Honoraria, Research Funding; Pfizer: Research Funding. McDonald: Bayer, Sobi, Novartis, Amgen, argenx: Honoraria; Grifols: Research Funding. Jain: GBT: Speakers Bureau; Novartis: Speakers Bureau; Argenx: Other: advisory board; Sanofi: Other: advisory board; DOVA: Other: advisory board. Oliva: Novartis, Celgene, Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Daiichi: Consultancy; Alexion, argenx, Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Hultberg: argenx: Current Employment, Patents & Royalties. Gandini: argenx: Current Employment, Current equity holder in publicly-traded company, Divested equity in a private or publicly-traded company in the past 24 months. Hofman: argenx: Current Employment. Van Bragt: Curare Consulting BV: Other: Partner; argenx: Consultancy. Parys: argenx: Current Employment. van Hoorick: argenx: Current Employment. Miyakawa: Sanofi: Consultancy; Zenyaku Kogyo: Consultancy; Sanofi: Research Funding; argenx: Consultancy, Research Funding. Broome: Alexion, argenx, Apellis, Sanofi: Honoraria.

Can calf age be estimated using a combination of serum gamma-glutamyl transferase, total protein and immunoglobulin G?

Our aim was to test a novel method for estimating the age of young calves, using serum γ-glutamyl transferase (GGT) activity, total protein concentration and immunoglobulin G (IgG) concentration.Blood samples were taken from 59 dairy calves at 2, 4, 6, 8, 10, 12, and 14 days of age, and serum GGT activity, total protein concentration, and IgG concentration were measured. Bayesian regression models were used to estimate the association of GGT, total protein, and IgG, with calf age. A multivariate hierarchical regression model was then created, and the model's reliability in estimating the age of simulated subjects was assessed.The univariate models showed a strong within-calf relationship between age and GGT (conditional R2 (cR2) = 0.93), and age and total protein (cR2 = 0.75), while the relationship between calf age and IgG was less consistent (cR2 = 0.63). There was a high degree of variation between calves for these parameters, particularly for the relationship between age and total protein (marginal R2 (mR2) 0.02), and age and IgG (mR2 0.01); somewhat less between-calf variation was seen for GGT (mR2 0.30).For the final multivariate model, we tested the model reliability by simulating new subjects. The credible intervals for estimates of calf age generated from the model were wide, indicating poor reliability. We concluded that single measurements of serum GGT activity, total protein concentrations and IgG concentrations cannot be used to reliably estimate the age of young calves to within 1–2 days.

Suitability of Protein Content Measured by MilkoScan FT-Plus Milk Analyzer to Evaluate Bovine and Ovine Colostrum Quality.

Simple SummaryA rapid and reliable method for assessing colostrum quality is needed to ensure enough immunoglobulins available to offspring in order to avoid the failure of the passive transfer of immunity. This study evaluates MilkoScan FT-plus as a rapid tool for the evaluation of immunoglobulin content indirectly by protein content measurement and thus colostrum quality with a particular focus on bovine and ovine colostrum. The results indicate that MilkoScan FT-plus has good agreement with the reference method for the measurement of immunoglobulin concentration in colostrum represented by the radial immunodiffusion method.The objective of this study was to evaluate MilkoScan FT-plus for the estimation of the immunoglobulin G (IgG) content in bovine and ovine colostrum. Between April and May 2016, a total of 94 colostrum samples (54 from Simmental dairy cows and 39 from Sarda ewes) were collected within 6 h (T0) and after 24 h (T24) from parturition. Colostrum samples were subjected to the radial immunodiffusion (RID) assay for the quantification of IgG and to MilkoScan FT-plus for the estimation of protein content (TP, %), which was then used as an indirect method for the evaluation of colostrum quality. To compare the two methods, correlation and regression analysis of IgG quantification by RID and protein (%) content estimation by MilkoScan FT-plus data was performed using Procedure CORR and Procedure REG of SAS, respectively (version 9.3, SAS Institute Inc., Cary, NC, USA). Thresholds for the classification of good colostrum quality (as determined by RID assay, the gold standard method) were set at 50 g of IgG/L in cows and 20 g of IgG/L in ewes. The concentration of IgG in bovine colostrum assayed by RID showed a variation ranging from 41.45 to 199.97 g/L with an average of 99.85 ± 40.84 g/L at T0, and from 2.83 to 75.93 g/L with an average of 19.76 ± 19.01 g/L at T24. Regarding ovine colostrum, the concentration of IgG assayed by RID ranged from 34.45 to 156.32 g/L with an average value of 77.82 ± 37.58 g/L at T0, and from 5.6 to 69.74 g/L with an average of 27.90 ± 19.81 g/L at T24. Colostrum TP ranged from 3.70 to 23.96% for bovine colostrum and 6.32 to 22.88% for ovine colostrum using MilkoScan FT-plus. MilkoScan FT-plus and RID data were highly and significantly correlated (r = 0.91 for bovine and r = 0.94 for ovine colostrum), and regression analysis showed a strong relationship between IgG concentration provided by RID assay and TP provided by MilkoScan FT-plus (R2 = 0.84 and 0.88 for bovine and ovine, respectively). Optimal cut-off points for the greatest accuracy of TP (%) determined by MilkoScan FT-plus were 12.8% in cows [with 88.9% sensitivity (Se) and 100% specificity (Sp)] and 9% in ewes (with 96.7% Se and 100% Sp). In conclusion, these outcomes indicate that MilkoScan FT-plus as an indirect method may be a reliable tool for the estimation of the total IgG concentration and quality in bovine and ovine colostrum. Moreover, the cut-off levels of 12.8% for bovine and 9% for ovine of TP, seem sufficient to ensure that all poor-quality colostrum can be classified as such, with only a low proportion of good-quality colostrum being misclassified as poor-colostrum, thereby increasing the probability of delivering good-quality colostrum to new-born calves and lambs.

Comparison of Total Immunoglobulin G in Ante- and Postmortem Blood Samples from Tissue Donors

Background: A serology testing for infectious diseases (HIV, hepatitis B and C, syphilis) is mandatory in tissue donors. In many donors postmortem blood is the only sample available. Even though serological tests and nucleic acid amplification tests (NAT) used are validated for postmortem blood, a characterization of those blood samples is not yet established. We therefore investigated the total immunoglobulin G (IgG) content in postmortem blood of tissue donors and compared it to a corresponding antemortem blood sample. Methods: Ante- and postmortem blood samples were obtained from 100 consecutive tissue donors. The total IgG of all samples was measured using an immune-turbidometric test on the AU 480 Chemistry Analyzer (Beckman Coulter). Results: The mean total IgG concentration of antemortem blood samples from all 100 donors was 8.9 g/L ± 3.7 g/L (median 8.9 g/L, range 1.5 to 23.8 g/L). In 80 donors the IgG concentration in the antemortem blood sample was within the normal range with values ≥6 g/L (mean 10.0 g/L ± 3.3 g/L, median 9.3 g/L,). The total IgG concentration of the postmortem blood samples was lower with 7.2 g/L ± 3.2 g/L (median 6.7 g/L, range 0.6 to 18.2 g/L). The difference between the values of the antemortem and postmortem blood samples was 1.7 g/L ± 2.6 g/L (16.3%) (median 1.6 g/L, range –7.7 to 10.1 g/L). In 36 donors this difference was less than 10%, in 23 it was between 10 and 25%, in 33 between 26 and 50%, and in 8 over 50%. In 57 donors the total IgG in the postmortem blood sample was within the normal range with ≥6 g/L, in 53 of them also the value of the antemortem blood sample was within the normal range. No correlation for total IgG was found regarding the donor characteristics (age, sex, disease) and the sample characteristics (hemolysis, postmortem time). Conclusion: Total IgG values in antemortem samples were below the lower limit of 6 g/L in 20% of the cases. Total IgG was significantly lower in the postmortem samples compared to the antemortem samples, while 57% were still above the lower limit. No correlation with the postmortem time could be found. This lowered IgG levels should be payed attention to when using postmortem blood for infectious serology testing. Additional NAT testing should be considered.

Adjustments for oral fluid quality and collection methods improve prediction of circulating tetanus antitoxin: Approaches for correcting antibody concentrations detected in a non-invasive specimen

ObjectivesTo examine whether anti-tetanus toxoid (anti-TT) immunoglobulin G (IgG) levels measured in oral fluid and adjusted for collection difficulties and specimen quality are associated with total IgG and anti-TTIgG in oral fluid and assess if statistical adjustment for them improves prediction of anti-TT IgG in serum. Methods267 children, ages 12 to 15 months, enrolled in the M-SIMU randomized controlled trial participated in this nested cross-sectional analysis. Venous blood and oral fluid (OF) specimens were collected, and OF collection difficulties such as crying or gagging were recorded. OF volume was documented and total IgG was measured in OF specimens and anti-TT IgG was measured in OF and serum by enzyme immunoassay (EIA). Collection difficulties, volume and sociodemographic characteristics were assessed in relation to total IgG and anti-TT IgG in OF via multivariate regression. These models were extended to evaluate the association between anti-TT IgG in OF and in serum. A prediction model was developed to adjust anti-TT IgG in OF estimates as proxy for serum. ResultsBlood in the specimen, sores in the mouth and crying were positively associated with total IgG concentration while high oral fluid volume and sucking on the swab were inversely associated. None were significant predictors of anti-TT IgG in OF after adjusting for total IgG (geometric mean [GM] ratio: 1.99; 95% confidence interval: 1.78–2.24) and vaccination history (GM ratio: 2.44; 95% CI: 1.98–3.01). When predicting anti-TT IgG levels in serum with OF, total IgG modified the effect of anti-TT IgG in OF. ConclusionsAnti-TT IgG in OF is a good proxy for levels in serum, after controlling for total IgG in the specimen and other variables. Post hoc adjustments for OF volume and total IgG concentration are an important consideration when conducting serosurveys with oral fluid.

Effect of Soy Lecithin Supplementation in Beef Cows before Calving on Colostrum Composition and Serum Total Protein and Immunoglobulin G Concentrations in Calves.

Simple SummaryUntil recently, fat supplements were considered merely as a source of energy for cows during transition. However, individual fatty acids included in fat supplements may clearly induce different production and metabolic responses, which in consequence change the nutritional value of bovine colostrum. Therefore, it is necessary to consider the type of fat additive to use in feed ration. This study aimed to determine an effect of soy lecithin supplementation on beef cow’s colostrum composition and selected blood parameters in their calves. Obtained results suggest that soy lecithin addition in cows before calving has a beneficial impact on colostrum composition. This concerns mainly an increase of linoleic acid in colostrum, which may influence IgG activity in calf serum. In turn, higher content of these components in colostrum may contribute to improve calves’ survival rate during the first weeks of their life.The aim of this study was to investigate the impact of soy lecithin supplementation in beef cow’s nutrition on colostrum composition and serum concentrations of immunoglobulin G (IgG) and serum total protein (STP) in calves. Twenty pregnant Charolaise cows were assigned to two groups. In the supplementation group (n = 10) during the last four weeks of pregnancy, soy lecithin was administrated in an amount of 20 g/cow/day. In both groups, basic composition (protein, fat, lactose, dry matter), somatic cell count (SCC), total bacteria count (TBC), IgG concentration, and fatty acids profile were determined in colostrum samples. Moreover, STP and IgG concentration were measured in calves’ blood samples on the 3rd, 7th, 14th, and 21st days of life, mothered by supplementation and control cows. Animals fed with soy lecithin before calving produced colostrum with a higher (p = 0.049) level of linoleic acid (C18:2 n-6). In addition, these results showed that soy lecithin supplementation has contributed to an increase (p = 0.029) of serum IgG in calves on the 14th day of life. The impact of such change in colostrum on IgG levels on calves serum and their half-life need further analysis.

Comparative humoral immune response against cytopathic or non-cytopathic bovine viral diarrhea virus infection

Bovine viral diarrhea virus (BVDV) infection causes immune dysfunction. The current study investigated the effect of cytopathic (cp) or noncytopathic (ncp) strains of BVDV on immunomodulation by the levels of total serum immunoglobulin G (IgG), the IgG1, IgG2, BVDV neutralizing antibodies and total white blood cell (WBC) count. Twenty (20) BVDV seronegative dairy calves (5–6 months old) were divided in two groups of ten. The animals were infected with either a cp or ncp virus isolated from the same animal (ncp BVDV1b-TGAN or cp BVDV1b-TGAC). One group of 10 was infected with ncp TGAN while the other group of 10 was infected with cp TGAC. Calves infected with cp BVDV had a significant decrease in total IgG as well as IgG1 concentration at 7 days post infection (DPI) that recovered by 21 DPI (total IgG) and 35 DPI (IgG1), respectively. There was no effect of ncp BVDV infection on total IgG concentration in the first 7 days of infection (DOI); however, IgG1 concentration was significantly reduced and IgG2 concentration was significantly increased at 7 DOI. At 35 DPI, ncp TGAN-infected calves had significantly higher total IgG, IgG1 as well as IgG2 compared to cp TGAC-infected calves. Ncp BVDV induced higher BVDV homologous and heterologous neutralizing antibodies compared to the cp BVDV strain. Calves infected with ncp BVDV had significantly reduced WBC counts at 7 DPI that recovered by 14 DPI. Overall, these findings indicate that humoral immunosuppression occurs early following BVDV infection with the largest effect on IgG1 levels.

Salivary total Immunoglobulin G as a surrogate marker of oral immune activity in salivary bioscience research

The integration of salivary biomeasures in biobehavioral, psychophysiological, and clinical research has greatly expanded our ability to study the biopsychosocial processes underlying health. Much of this research, however, has failed to adequately assess and adjust for the impact of oral immune activity on salivary biomeasure concentrations and associations with serum levels. Aiming to improve the validity and reliability of salivary biomeasure data, we examine salivary total Immunoglobulin G (IgG) as a potential surrogate marker of oral inflammation and immune activity. During a single study visit in Baltimore, Maryland, healthy young adult participants provided matched blood and saliva samples (N=99; age 18–37 years, 42% female) and completed an oral health questionnaire. Biospecimens were assayed for total IgG and immune markers related to inflammation (cytokines), blood in saliva (transferrin), and tissue remodeling (matrix metalloproteinase-8). Total IgG (μg/mL) concentrations were higher in serum than saliva. Salivary total IgG was associated with some self-reported oral health measures, and strongly positively associated with all salivary immune markers. Controlling for salivary total IgG may be a feasible, affordable approach to adjusting salivary biomeasure findings for the influence of the oral immune environment when it is not possible or practical to obtain clinical oral health data.

Durable preservation of antiviral antibodies after CD19-directed chimeric antigen receptor T-cell immunotherapy

AbstractThe long-term effects of CD19-targeted chimeric antigen receptor–modified T-cell immunotherapy (CD19-CARTx) for B-cell malignancies on humoral immunity are unclear. We examined antiviral humoral immunity in 39 adults with B-cell malignancies who achieved durable complete remission without additional therapy for >6 months after CD19-CARTx. Despite CD19+ B-cell aplasia in all patients, the incidence of viral infections occurring >90 days post–CD19-CARTx was low (0.91 infections per person-year). Because long-lived plasma cells are CD19− and should not be direct targets of CD19-targeted chimeric antigen receptor T cells, we tested the hypothesis that humoral immunity was preserved after CD19-CARTx based on linear mixed-effects models of changes in serum total immunoglobulin G (IgG) concentration, measles IgG concentration, and the number of viruses or viral epitopes to which serum IgG was directed (the “antivirome”) using the novel VirScan assay. Samples were tested pre–CD19-CARTx and ∼1, 6, and 12 months post–CD19-CARTx. Although total IgG concentration was lower post–CD19-CARTx (mean change, −17.5%), measles IgG concentration was similar (mean change, 1.2%). Only 1 participant lost measles seroprotection post–CD19-CARTx but had undergone allogeneic hematopoietic cell transplantation before CD19-CARTx. The antivirome was also preserved, with mean absolute losses of 0.3 viruses and 6 viral epitopes detected between pre- and post–CD19-CARTx samples. Most participants gained IgG to ≥2 epitopes for ≥2 viruses, suggesting that humoral immunity to some viruses may be maintained or recover after successful CD19-CARTx. These findings may differ in children. Studies of immunoglobulin replacement and vaccination after CARTx are warranted.

S850 SAFETY AND EFFICACY OF AN ANTI‐FCRN ANTIBODY, ROZANOLIXIZUMAB, IN PATIENTS WITH PRIMARY IMMUNE THROMBOCYTOPENIA: INTERIM RESULTS OF A PHASE II, MULTIPLE‐DOSE STUDY

Background:Rozanolixizumab, a subcutaneous (SC) monoclonal antibody specific for the human neonatal Fc receptor (FcRn), is being developed with the aim of improving the lives of people with immunoglobulin G (IgG)‐mediated autoimmune diseases, by reducing pathogenic IgG autoantibodies.Aims:To report a planned interim analysis (13th Data Monitoring Committee review; data cut‐off: 02‐Aug‐2018) of an ongoing Phase II, open‐label study of rozanolixizumab in patients with primary immune thrombocytopenia (ITP) (NCT02718716).Methods:Eligibility criteria included: ≥18 years of age; diagnosis of primary ITP for ≥3 months prior to screening; platelet count &lt;30x109/L at screening and &lt;35x109/L at baseline; current/history of peripheral blood smear consistent with ITP. Eligible patients received 4 mg/kg (5 doses), 7 mg/kg (3 doses), 10 mg/kg (2 doses) or 15 mg/kg (1 dose) rozanolixizumab SC weekly; the study is ongoing with 20 mg/kg (1 dose). An 8‐week observation period followed dosing. Primary objective: evaluate safety and tolerability of rozanolixizumab by occurrence of treatment‐emergent adverse events (TEAEs); secondary objective: assess clinical efficacy through assessment of platelet count.Results:Median number of prior ITP therapies was 3.5–7.0, suggesting a difficult‐to‐treat population.39/54 (72%) patients reported ≥1 TEAE (104 TEAEs total). There were four serious TEAEs overall (none deemed treatment‐related by the investigator): bleeding from genital tract (4 mg/kg group), thrombocytopenia (10 mg/kg group), thrombocytopenia, platelet count decrease (both 15 mg/kg group). The most frequently reported TEAE was headache (17/31 overall; all mild or moderate in severity). 1 patient in each of the 4 mg/kg, 7 mg/kg and 10 mg/kg groups and 8 patients in the 15 mg/kg group reported TEAEs deemed treatment‐related by the investigator, of which headache was the most frequent (0/15, 4 mg/kg; 1/15 (7%), 7 mg/kg; 1/12 (8%), 10 mg/kg; 5/12 (42%), 15 mg/kg). No deaths or treatment discontinuations due to TEAEs were reported. No clinically relevant changes were observed in all other routine safety parameters. No unexpected changes in total protein were observed.Clinically relevant improvements in platelet count (≥50x109/L) were observed across all dose groups; 4 mg/kg group: 5/15 (33%), 7 mg/kg group: 5/15 (33%), 10 mg/kg group: 6/12 (50%), and 15 mg/kg group: 8/12 (67%). Of those with a platelet count ≥50x109/L, a response was seen ≤8 days after first rozanolixizumab dose for 1/5 (4 mg/kg), 2/5 (7 mg/kg), 3/6 (10 mg/kg), and 7/8 (15 mg/kg) patients. Maximum mean (range) decreases in total IgG concentration were observed at Day 29, after 4 doses, for the 4 mg/kg group (43.6%, 21.9–68.6); at Day 22, after 3 doses, for the 7 mg/kg group (49.9%, 29.5–65.5); at Day 15, after 2 doses, for the 10 mg/kg group (63.8%, 38.4–75.0) and at Day 8, after a single dose, for the 15 mg/kg group (52.3%, 30.1–68.0) (Figure).Summary/Conclusion:Rozanolixizumab demonstrated a well‐tolerated safety profile across all reported dose groups. Clinically meaningful platelet responses were observed for all doses; response rate increased in line with dose, maximum response was seen after the single 15 mg/kg SC dose. For patients achieving a platelet response, the time to response reduced with increasing dose. Rapid decreases in IgG concentration were observed. Data support the rationale that targeting the natural IgG recycling mechanism could offer a new treatment paradigm for people with IgG‐driven autoimmune diseases.image

Primiparous and Multiparous Sows Have Largely Similar Colostrum and Milk Composition Profiles Throughout Lactation.

Simple summaryProgeny born to primiparous sows (gilt progeny) are born lighter, grow slower, and have higher rates of mortality than piglets born to multiparous sows. An understanding of why this might be the case is necessary to implement management strategies that improve the health and welfare of first-litter piglets and increase their production efficiency. Differences in the composition of colostrum and milk between primiparous and multiparous sows might be a contributing factor. Results from this study suggest that primiparous and multiparous sows (parities 3 and 4) have similar levels of immunoglobulin G and energetic components (net energy, fat, protein, and lactose) in colostrum and milk throughout the course of lactation. However, lower lactose levels from day 14 onwards in milk from primiparous sows compared to milk from multiparous sows may indicate that there is a reduction of lactose uptake into the mammary gland in primiparous sows during late lactation, which may reduce milk volume. Lower growth rates and higher rates of mortality in gilt progeny are therefore likely to be as a result of lower colostrum and milk production in primiparous sows and (or) an inability of their piglets to digest these nutritional components effectively.It is important to understand the biological factors influencing the poorer lifetime performance of gilt progeny in comparison to sow progeny and determine whether this may be partially due to differences in lactation performance between primiparous and multiparous sows. It was hypothesized that primiparous sows would have lower levels of immunoglobulin G (IgG) in colostrum and milk compared to multiparous sows, and lower levels of other energetic components. Differences in colostrum and milk composition between ten primiparous and ten multiparous sows (parities 3 and 4) from a commercial herd were examined throughout lactation (day 0, 1, 2, 3, 7, 14, and 21). Overall, there were no (p ≥ 0.05) parity differences in total IgG, fat, protein, lactose, and net energy (NE) concentrations. Primiparous sows had higher lactose levels at day 2 (parity by timepoint interaction; p = 0.036) and lower NE at day 3 (p = 0.091), and multiparous sows had higher lactose levels at days 14 and 21. Results suggest that shortcomings of gilt progeny are unlikely due to insufficient nutrient levels in colostrum and milk, and more likely to reduced colostrum and milk intake and their capacity to digest and absorb each component.

Estrogen induces St6gal1 expression and increases IgG sialylation in mice and patients with rheumatoid arthritis: a potential explanation for the increased risk of rheumatoid arthritis in postmenopausal women

BackgroundRheumatoid arthritis (RA) preferentially affects women, with the peak incidence coinciding with estrogen decrease in menopause. Estrogen (E2) may therefore have intrinsic immune-regulatory properties that vanish with menopause. Fc sialylation is a crucial factor determining the inflammatory effector function of antibodies. We therefore analyzed whether E2 affects immunoglobulin G (IgG) sialylation.MethodsPostmenopausal (ovariectomized) mice were immunized with ovalbumin and treated with E2 or vehicle. Total and ovalbumin-specific IgG concentrations, sialylation, and Fcγ receptor expression were analyzed. Postmenopausal women with RA receiving hormone replacement therapy, including E2, or no treatment were analyzed for IgG sialylation. Furthermore, effects of E2 on the expression of the sialylation enzyme β-galactoside α2,6-sialyltransferase 1 (St6Gal1) were studied in mouse and human antibody-producing cells.ResultsE2 treatment significantly increased Fc sialylation of total and ovalbumin-specific IgG in postmenopausal mice. Furthermore, E2 led to increased expression of inhibitory Fcγ receptor IIb on bone marrow leukocytes. Treatment with E2 also increased St6Gal1 expression in mouse and human antibody-producing cells, providing a mechanistic explanation for the increase in IgG-Fc sialylation. In postmenopausal women with RA, treatment with E2 significantly increased the Fc sialylation of IgG.ConclusionsE2 induces anti-inflammatory effector functions in IgG by inducing St6Gal1 expression in antibody-producing cells and by increasing Fc sialylation. These observations provide a mechanistic explanation for the increased risk of RA in conditions with low estrogen levels such as menopause.

Factors Affecting the FcRn-Mediated Transplacental Transfer of Antibodies and Implications for Vaccination in Pregnancy.

At birth, neonates are particularly vulnerable to infection and transplacental transfer of immunoglobulin G (IgG) from mother to fetus provides crucial protection in the first weeks of life. Transcytosis of IgG occurs via binding with the neonatal Fc receptor (FcRn) in the placental synctiotrophoblast. As maternal vaccination becomes an increasingly important strategy for the protection of young infants, improving our understanding of transplacental transfer and the factors that may affect this will become increasingly important, especially in low-income countries where the burden of morbidity and mortality is highest. This review highlights factors of relevance to maternal vaccination that may modulate placental transfer—IgG subclass, glycosylation of antibody, total maternal IgG concentration, maternal disease, infant gestational age, and birthweight—and outlines the conflicting evidence and questions that remain regarding the complexities of these relationships. Furthermore, the intricacies of the Ab–FcRn interaction remain poorly understood and models that may help address future research questions are described.

Decreased Serum Concentration of Total IgG Is Related to Tumor Progression in Gastric Cancer Patients

There is accumulating evidence that shows cell-mediated immunity regulated by T cells is impaired in cancer patients. Unfortunately, the mechanisms by which B cells participate in tumor immunity are only partially understood. The serum concentration of Immunoglobulin G (IgG) was measured by Enzyme-Linked ImmunoSorbent Assay (ELISA) in patients with gastric cancer. Immunohistochemistry was also performed using the anti- cluster of differentiation (CD)134 antibody to evaluate the number of plasma cells in the tumor tissue. The total serum IgG concentration was significantly lower in patients with lymph node metastasis compared with patients without metastasis. The serum concentration of total IgG at stage III/IV was significantly lower compared with tumors classified as stage I/II. A decreased serum concentration of total IgG and IgG1 was significantly related to a poor prognosis for gastric cancer patients. Furthermore, multivariate analysis indicated that the serum concentration of IgG and lymph node metastasis were independent prognostic indicators for poorer survival. The number of plasma cells was significantly lower in gastric cancer tissue compared with non-cancerous gastric mucosa. A decreased serum concentration of IgG was closely related to poor prognosis, indicating the possibility that impaired antibody-mediated immunity is associated with tumor progression in patients with gastric cancer.