Immunoglobulin Class G Research Articles

Impact of Sex, Age and Body Habitus on RBD-specific Antibody Response After Two Doses of Sinopharm BBIBP-CorV Vaccine

Background: Mongolia started its nationwide vaccination campaign against COVID-19 on 23 February 2021 after receiving the first batch of the inactivated BBIBP-CorV. Age and body habitus of vaccinees may be associated with the immune effecter functions. Several systematic reviews and meta-analyses suggested lower immunogenicity of vaccines against SARS-CoV-2 infection in the older adult population and obese individuals. We aimed to establish a possible relationship between post-vaccine seroconversion rate and some biometric characteristics in the Mongolian cohort of vaccinees after two shots of the Sinopharm BBIBP-CorV vaccine. Materials and Methods: We collected serum samples from 846 eligible vaccinees before the first dose of the BBIBP-CorV vaccine and 21-28 days after the second dose of the same vaccine. Anti-SARS-CoV-2 Receptor Binding Domain (RBD) Immunoglobulin class G (IgG) and M (IgM) titer were measured in all samples. Results: 686 (81.1%) of 846 vaccinees received the Sinopharm BBIBP-CorV vaccine demonstrated seroconversion. Vaccinees with seroconversion had a younger mean age and lower mean body-mass index (BMI) than non-responders. Seroconversion rate according to age of vaccinees tends to decrease and obese vaccinees demonstrated a greater portion among non-responders. The Optimal Cut-Point (OCP) of age for seroconversion was found to differ significantly in male and female vaccinees. BMI has shown prediction ability for seroconversion only in male vaccinees but not in females. Using Receiver Operating Characteristics (ROC) analysis, we found 39 years for males and 41 years for females as a crucial milestone increasing the probability of seronegativity 2.5 times on average. A BMI higher than 29.1kg/m2 in male vaccinees was considered an acceptable predictor for seroconversion increasing the probability of seronegativity 2.4 times on average. Conclusion: The above findings allow us to summarize the sex-adjusted approach to biometric characteristics has an improved predictiveness for post-vaccine antibody response.

Анализ состояния микрососудистого русла и планирование реабилитационных мероприятий у детей после перенесенной новой коронавирусной инфекции

Aim: to analyze microcirculation in children who recovered from coronavirus disease 2019 (COVID-19) in order to identify microcirculatory disorders and their association with clinical symptoms and to design rehabilitation measures Patients and Methods: the study included 78 children aged 7–15 years who recovered from COVID-19. All children had negative SARS- CoV-2 RNA tests (oropharyngeal and naso-pharyngeal swabs) by PCR and positive blood SARS-CoV-2 immunoglobulin class G (IgG). The control group included 30 healthy age-matched children who did not experience COVID-19. Microcirculation was evaluated by slit lamp biomicroscopy for imaging bulbar conjunctival microvasculature with further morphometric processing of images. Exclusion criteria included inflammatory eye diseases, acute bronchopulmonary diseases or their exacerbation, arterial hy-pertension, and obesity grades 2 to 4. Results: a decrease in the count of capillaries, pre- and postcapillaries, and 1 st-order ar-terioles, as well as a decrease in the percentage of 1st-order arterioles were identified in indi-viduals who had been asymptomatic or had experienced mild COVID-19 symptoms 3 to 12 months prior. Additionally, an increase in the count of 1st-order venules and arteriolar venular anastomoses, 2nd-order arterioles and venules, and 1st-order arteries and veins was revealed. The coefficient of irregularity in venular caliber in severe cases of COVID-19 was 0.62±0.05, which was significantly (p<0.023) greater than that in asymptomatic cases of COVID-19 (0.43±0.03). This indicates a persistent reduction in venous tone Conclusions: our study demonstrated microvascular disorders in children in the long-term period following COVID-19, indicating a long-term maladaptation of microcirculation These children can be classified as belonging to the risk group for microcirculatory disorders in the post- COVID period. KEYWORDS: children, COVID-19, long COVID, microvasculature, capillaries, venules, arterioles, microcirculation. FOR CITATION: Mikheeva I.G., Kurasova O.B., Milekhina M.Yu., Moiseev A.B., Kuznetsova N.I., Kalinovskaya I.I., Zimina N.A., Vereshchagina T.G. Study of microcirculation and the scheduling of rehabilitation measures in children who have recovered from coronavirus disease 2019. Russian Journal of Woman and Child Health. 2024;7(2):171–176 (in Russ.). DOI: 10.32364/2618-8430-2024-7-2-13.

Determination of optimum nanofiltration conditions for the manufacturing process of human normal immunoglobulin G for intravenous administration

Scientific relevance. Medicinal products based on immunoglobulin class G (IgG) from human plasma are widely used in clinical practice to treat bacterial and viral infections, primary and secondary immunodeficiencies, and autoimmune diseases. Nanofiltration is a way to mitigate the risk of in-process contamination of raw materials with various pathogens, including viruses. Therefore, it is relevant to investigate the development and implementation of additional viral inactivation and/or elimination steps.Aim. This study aimed to develop and validate optimum nanofiltration conditions and to scale up the nanofiltration step for the manufacturing of human IgG for intravenous administration.Materials and methods. The study used a solution of IgG from plasma fractions II and III. The authors paired nanofilters manufactured by Planova 20N and BioEx (Asahi Kasei, Japan), Viresolve Pro (Merck Millipore, USA), Virosart HC and HF (Sartorius, Germany), and Pegasus SV4 and Prime (Pall, USA) with Sartopore polyethersulphone prefilters by Sartorius (Germany), Virosart MAX polyamide prefilters by Sartorius (Germany), and EKX-P regenerated cellulose prefilters by Pall (Germany). Virus reduction validation studies were performed with model viruses (human immunodeficiency virus type 1, porcine transmissible gastroenteritis virus, porcine parvovirus, murine encephalomyocarditis virus, and bovine viral diarrhoea virus) in the laboratories of the N.F. Gamaleya centre. The sample data analysis involved calculating mean values with 95% confidence intervals.Results. For all the selected combinations of prefilters and filters, the maximum nanofiltration throughput depended on the IgG concentration in the test solution. With the combination of an EKX-P filter with a Pegasus SV4 nanofilter, the maximum throughput and the IgG yield reached 6300 g/m2 and 95%, respectively. When combined with a Planova 20N nanofilter, EKX-P and Sartopore (polyethersulphone) filters provided a maximum throughput of up to 2980 g/m2 and an IgG yield of almost 100%, provided that the test solution had an IgG concentration of 10 g/L. With different filter combinations, virus reduction levels ranged from 4.00±0.05 to 4.75±0.04 log10 for human immunodeficiency virus type 1, from 4.30±0.04 to 4.55±0.06 log10 for porcine transmissible gastroenteritis virus, from 5.38±0.08 log10 to 5.57±0.04 log10 for murine encephalomyocarditis virus, 5.12±0.10 log10 to 5.25±0.08 log10 for porcine parvovirus, and exceeded 5.00 log10 for bovine viral diarrhoea virus. The virus reduction levels achieved were not statistically associated with prefilter brands.Conclusions. The study demonstrated that nanofiltration was effective at removing viruses with various virion sizes and physicochemical characteristics, including viruses as small as parvovirus B19. The levels of virus reduction exceeded 4 log10 and met the acceptance criteria.The laboratory-scale nanofiltration parameters and the corresponding filtration times, as well as IgG yields, did not change when the process was scaled up. Therefore, nanofiltration is an effective and productive technique that helps eliminate various types of viruses and considerably improve viral safety without affecting the quality of biological medicinal products.

Antibody responses to BNT162b2 SARS-CoV-2 mRNA vaccine among healthcare workers and residents of long-term care facilities: A cohort study in Northern Italy.

Long-term care facilities (LTCFs) have been severely impacted by COVID-19, with a disproportionate amount of SARS-CoV-2 infections and related deaths occurring among residents. This study is part of an ongoing multicenter, prospective cohort study conducted among healthcare workers(HCWs) and residents of 13 LTCFs in Northern Italy designed to evaluate SARS-CoV-2 specific immunoglobulin class G (IgG) titers before and following vaccination with Pfizer/BNT162b2 SARS-CoV-2 mRNA vaccine (two doses of vaccine, 21 days apart). Serum samples were obtained from participants (t0) before vaccination, and (t1) 2 weeks after and analyzed to determine anti-S1 IgG antibodies. Five hundred and thirty-fourparticipants were enrolled (404 subjects participated in both blood draws). Seropositivity was 50.19% at t0and 99% at t1, with a significant difference in IgG titers. A higher proportion of residents were seropositive at t0 compared withHCWs, with significantly higher IgG titers among residents at both t0 and t1. Pre-existing immunity also had a significant effect on postvaccination IgG titers. However, a significant difference in titers at t1 between HCWsand residents considering only participants seropositive at t0 was found, with higher median titers among previously seropositive residents. Findings of this study provide scientific evidence endorsing the policy of universal vaccination in LTCFs.

Antibody Response to Inactive SARS-CoV-2 Vaccination in a Cohort of Elderly Patients Living with Obesity

Introduction: Obesity and aging negatively affect the immune system and host defense mechanisms, increasing vulnerability to and worsening prognosis of infectious diseases, leading to vaccine failure. Our aim was to investigate the antibody response against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike antigens and the risk factors affecting antibody levels in elderly patients living with obesity (PwO) after inactive SARS-CoV-2 vaccine (CoronaVac) administration. Methods: One hundred twenty-three consecutive elderly patients with obesity (age ≥65 years, body mass index [BMI] ≥30 kg/m²) and 47 adults with obesity (age 18–64 years, BMI ≥30 kg/m²) admitted between August and November 2021 were enrolled. Seventy-five nonobese elderly people (age ≥65 years, BMI 18.5–29.9 kg/m²) and 105 nonobese adults (age 18–64 years, BMI 18.5–29.9 kg/m²) were recruited from subjects who visited the Vaccination Unit. SARS-CoV-2 spike protein antibody titers were measured in patients with obesity and nonobese controls who received two doses of CoronaVac. Results: SARS-CoV-2 levels of patients with obesity were found to be significantly lower than those of nonobese elderly individuals who had non-prior infection. There was no difference in SARS-CoV-2 levels between patients with obesity and nonobese individuals with prior infection. Age and SARS-CoV-2 level were found to be highly correlated in the correlation analysis in the group of elderly individuals (r: −0.184). In multivariate regression analysis, when SARS-CoV-2 immunoglobulin class G (IgG) was regressed on age, sex, BMI, type 2 diabetes mellitus, and hypertension (HT), HT was found to be an independent factor of the SARS-CoV-2 level (β: −2,730). Conclusion: In the non-prior infection group, elderly patients with obesity generated significantly reduced antibody titers against SARS-CoV-2 spike antigen after CoronaVac vaccine compared to nonobese people. It is anticipated that the results obtained will provide invaluable information about SARS-CoV-2 vaccination strategies in this vulnerable population. Antibody titers may be measured, and booster doses should be delivered accordingly in elderly PwO for optimal protection.

Hiding Payload Inside the IgG Fc Cavity Significantly Enhances the Therapeutic Index of Antibody-Drug Conjugates.

The inadequate understanding of the structure-activity relationship (SAR) of glycosite-specific antibody-drug conjugates (ADCs) hinders its design and development. Herein, we revealed the systemic SAR and structure-toxicity relationship (STR) of gsADCs by constructing 50 gsADC structures bearing three glycan subtypes and diverse linker-drug combinations. According to the results, extra hydrophilic linkers are indispensable for the intact glycan-based gsADCs to achieve better in vivo efficacy. Meanwhile, the gsADCs that conjugate linker-drug complexes onto the terminal sialic acid are more stable and potent than the ones conjugated onto the terminal galactose in vivo. Notably, the LacNAc-based gsADCs, which shortened the spacer and located the linker-drug more inside the immunoglobulin class G (IgG) Fc cavity, showed excellent hydrophilicity, in vivo activity, pharmacokinetics, and safety. Conclusively, we found that hiding the linker-toxin into the Fc cavity can significantly enhance the therapeutic index of LacNAc-based gsADCs, which will benefit the further design of ADCs with optimal druggability.

Mapping of SARS-CoV-2 IgM and IgG in gingival crevicular fluid: Antibody dynamics and linkage to severity of COVID-19 in hospital inpatients

Mapping of SARS-CoV-2 IgM and IgG in gingival crevicular fluid: Antibody dynamics and linkage to severity of COVID-19 in hospital inpatients

Circulating IgG Levels in SARS-CoV-2 Convalescent Individuals in Cyprus.

Long-term persistence and the heterogeneity of humoral response to SARS-CoV-2 have not yet been thoroughly investigated. The aim of this work is to study the production of circulating immunoglobulin class G (IgG) antibodies against SARS-CoV-2 in individuals with past infection in Cyprus. Individuals of the general population, with or without previous SARS-CoV-2 infection, were invited to visit the Biobank at the Center of Excellence in Biobanking and Biomedical Research of the University of Cyprus. Serum IgG antibodies were measured using the SARS-CoV-2 IgG and the SARS-CoV-2 IgG II Quant assays of Abbott Laboratories. Antibody responses to SARS-CoV-2 were also evaluated against participants’ demographic and clinical data. All statistical analyses were conducted in Stata 16. The median levels of receptor binding domain (RBD)-specific IgG in 969 unvaccinated individuals, who were reportedly infected between November 2020 and September 2021, were 432.1 arbitrary units (AI)/mL (interquartile range—IQR: 182.4–1147.3). Higher antibody levels were observed in older participants, males, and those who reportedly developed symptoms or were hospitalized. The RBD-specific IgG levels peaked at three months post symptom onset and subsequently decreased up to month six, with a slower decay thereafter. IgG response to the RBD of SARS-CoV-2 is bi-phasic with considerable titer variability. Levels of IgG are significantly associated with several parameters, including age, gender, and severity of symptoms.

SARS-CoV-2 IgG antibody responses in rt-PCR-positive cases: first report from India.

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody responses remain poorly understood and the clinical utility of serological testing is still unclear.AimTo understand the relationship between the antibody response to SARS-CoV-2 infection and the demographics and cycle threshold (C t) values of confirmed RT-PCR patients.MethodologyA total of 384 serum samples were collected from individuals between 4–6 weeks after confirmed SARS-CoV-2 infection and tested for the development of immunoglobulin class G (IgG) against SARS-CoV-2. The C t values, age, gender and symptoms of the patients were correlated with the development of antibodies.ResultsIgG positivity was found to be 80.2 % (95 % CI, 76.2–84.2). Positivity increased with a decrease in the C t value, with the highest (87.6 %) positivity observed in individuals with C t values <20. The mean (±sd) C t values for IgG positives and negatives were 23.34 (±6.09) and 26.72 (±7.031), respectively. No significant difference was found for demographic characteristics such as age and sex and symptoms and antibody response. The current study is the first of its kind wherein we have assessed the correlation of the RT-PCR C t with the development of IgG against SARS-CoV-2.ConclusionAlthough C t values might not have any relation with the development of symptoms, they are associated with the antibody response among SARS-CoV-2-infected individuals.

Serological Evaluation of Human Antibodies of the Immunoglobulin Class A and G Against SARS-CoV-2 in Serum Collected in Newfoundland and Labrador.

The ability to detect antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently under investigation with various performance characteristics and indications for use. In this article, we analyzed the ability of the Abbott SARS-CoV-2 immunoglobulin class G (IgG), EuroImmun SARS-CoV-2 enzyme-linked immunosorbent assay (ELISA) IgG, and EuroImmun SARS-CoV-2 ELISA immunoglobulin class A (IgA) kits to detect evidence of previous infection with SARS-CoV-2. We tested 49 known coronavirus disease-19 (COVID-19) patients and 111 prepandemic stored serology specimens. This resulted in a sensitivity of 95.9%, 100.0%, and 91.3% and a specificity of 98.2%, 98.2%, and 90.8% respectively, using manufacturer recommended cutoffs after inconclusive results (one for EuroImmun IgG and five for EuroImmun IgA) being excluded in the final statistical analyses. Cross-reactivity of hepatitis C virus seropositive specimens was observed resulting in false positives (p < 0.05). If a two-tiered algorithmic approach was applied, that is, testing with Abbott SARS-CoV-2 assay followed by EuroImmun SARS-CoV-2 IgG, 100% specificity and sensitivity could be obtained after six inconclusive results were excluded from data set before statistical analyses. Performance characteristics presented demonstrate the superior performance of IgG class antibodies for investigating previous infections. In addition, utilizing a second antibody test for supplementary testing may significantly enhance performance, particularly in lower prevalence settings.

The role of antibody tests for COVID-19 in primary care.

The control of coronavirus 2019 disease (COVID-19) relies on implementing an effective testing and tracing strategy; the ideal would be a move to using rapid point-of-care tests (POCTs) in the community, to detect both active infections and to identify those already immune, as being tested in Liverpool.1 To date, largely laboratory-based virology testing (reverse transcription polymerase chain reaction (PCR) to detect viral ribonucleic acid from naso/oropharyngeal swabs) remains the gold standard for diagnosis. The role of COVID-19 antibody testing is limited, with few studies published about the diagnostic accuracy of POCTs that might be used in primary care. This article aims to summarise the current state of knowledge about the potential role of COVID-19 antibody testing in primary care. Following infection, we develop immunoglobulins (Ig) against SARS-CoV-2 proteins, including the diagnostically important nucleoprotein and/or spike proteins (N- and S-proteins, respectively). The median time of detection of anti- SARS-CoV-2 IgG is day 14 post-onset of symptoms (POS) (for IgM and IgA it is day 5), and it is detectable in 90% of individuals by then.2,3 Anti-N-protein immunoglobulin class G (IgG) is the most sensitive current target for serological detection, albeit its combined detection with anti-S improves sensitivity.4–6 IgA antibodies, implicated in mucosal surface defence, are detectable from the first day POS.3 A waning in IgG response has been reported,7 with potentially severe implications for long-term immunity depending upon the alternative effectiveness of memory T-cell-mediated immunity. There are suggestions that seropositive individuals are only at a lower risk of re-infection compared with seronegative individuals.8 There is no definitive evidence present about the protective effect, if any, of anti-SARS-CoV-2 antibody against reinfection and/or COVID-19 disease. Individuals previously infected with COVID-19 can serorevert and some who have seroconverted do not necessarily stop shedding the …

Reação imunoenzimática (ELISA) quantitativa para detecção de anticorpos IgG anti-DNA de dupla hélice

ABSTRACT Introduction: The detection of anti-double-stranded (ds) deoxyribonucleic acid (DNA) antibodies is one of the classification criteria for diagnosing systemic lupus erythematosus (SLE). Objective: To describe a quantitative enzyme-linked immunosorbent assay (ELISA) for detecting anti-dsDNA immunoglobulin class G (IgG) antibodies. Methods: The performance of ELISA was evaluated using the Crithidia luciliae indirect immunofluorescence test (CLIFT) as a reference. Anti-dsDNA IgG antibodies were screened by ELISA and CLIFT in serum samples from 127 patients with SLE, 56 patients with other diseases and 37 healthy persons. The Cochran Q test was used to compare the sensitivity and specificity of the reactions, with differences among the results being considered significant when p ≤ 0.05. Results: ELISA had a sensitivity of 92.9% and a specificity of 94.6%, whereas the sensitivity and specificity of CLIFT were 85.8% and 100%, respectively. ELISA was significantly more sensitive than CLIFT (p = 0.0027), whereas CLIFT was significantly more specific than ELISA (p = 0.0253). Conclusion: ELISA showed excellent results in terms of sensitivity and specificity, with a potential use in research and routine diagnostics.

Clinical, laboratorial diagnosis and prophylaxis of measles in Brazil

ABSTRACT Measles is an acute febrile exanthematic disease of viral etiology, highly contagious, being the cause of morbidity and mortality of children in developing countries, whereas it has become rarer in developed countries due to vaccination. Its differential diagnosis should be made with other childhood viral respiratory diseases such as influenza, rhinovirus and adenovirus, and exanthematic febrile diseases such as rubella, roseola and varicella. In tropical regions, it should be performed with dengue, zika and chikungunya. Its clinical picture presents the following phases: incubation, usually asymptomatic; a prodrome, in which fever, malaise, coryza can occur, besides Koplik’s signs; exanthematic, with presence of maculopapular exanthema after the fever condition that progresses to a craniocaudal evolution, with clinical improvement in uncomplicated cases. Common complications are pneumonia, otitis media, keratitis; the rarest are acute disseminated encephalomyelitis and subacute sclerosing panencephalitis. Nonspecific laboratory alterations are seen in the blood count. The specific laboratory diagnosis is based on the detection of viral ribonucleic acid (RNA) [polymerase chain reaction (PCR) of nasal swab samples, oral mucosa or urine]. Immunoglobulin class M (IgM) can be detected during the exanthematous period by enzyme-linked immunosorbent assay (ELISA), and immunoglobulin class G (IgG) throughout the convalescence period, and the detection of specific IgG by the plaque reduction neutralization test may also be performed. The prophylaxis of the disease is based on vaccination in children from 15 months in order to reach about 85% to 95% of the population, what confers herd immunity. Thus, vaccination is the most effective measure in combating measles, since the treatment consists only of clinical and symptomatic support.

Fcab-HER2 Interaction: a Ménage à Trois. Lessons from X-Ray and Solution Studies

The crystallizable fragment (Fc) of the immunoglobulin class G (IgG) is an attractive scaffold for the design of novel therapeutics. Upon engineering the C-terminal loops in the CH3 domains, Fcabs (Fc domain with antigen-binding sites) can be designed. We present the first crystal structures of Fcabs, i.e., of the HER2-binding clone H10-03-6 having the AB and EF loop engineered and the stabilized version STAB19 derived by directed evolution. Comparison with the crystal structure of the Fc wild-type protein reveals conservation ofthe overall domain structures but significant differences in EF-loop conformations. Furthermore, we present the first Fcab-antigen complex structures demonstrating the interaction between the engineered Fcab loops with domain IV of HER2. The crystal structures of the STAB19-HER2 and H10-03-6-HER2 complexes together with analyses by isothermal titration calorimetry, SEC-MALS, and fluorescence correlation spectroscopy show that one homodimeric Fcab binds two HER2 molecules following a negative cooperative binding behavior.

Clinical and laboratory diagnosis of Zika fever: an update

ABSTRACT Zika fever can be defined as an acute febrile viral illness, mainly transmitted by the mosquito of the genus Aedes. It makes a differential diagnosis from diseases caused by other flaviviruses, such as chikungunya and dengue fever. Many people with Zika virus (ZIKV) infection will not have symptoms or will only have mild clinical symptoms. The clinical conditions are nonspecific and characterized by low-grade fever, pruritic erythematous maculopapular rash, non-purulent conjunctival hyperemia without pruritus, arthralgia, myalgia, and headache. It is a benign, self-limiting and short-duration condition. Complications such as Guillain-Barre syndrome (GBS), spontaneous abortion and fetal malformations, mainly microcephaly and retinal lesions, may occur. The laboratory investigation is more important in cases suspected of ZIKV infection that have evolved with neurological complications, in pregnant women, abortion or congenital malformations, and is a key part for diagnostic definition. Real-time polymerase chain reaction (RT-PCR) can detect the virus in blood samples about four to seven days after the onset of symptoms. In urine, it is possible to identify viral ribonucleic acid (RNA) up to 15 days after clinical onset, even if viremia has ceased, and it is an alternative for late diagnosis. Serological tests may also be performed, while there may be cross-reactivity with other flaviviruses. Immunoglobulin class M (IgM) can be screened between the 2nd and 12th week after clinical presentation. The immunoglobulin class G (IgG) can be identified after the 15th day, and is present even in the convalescence and cure phase. Non-specific laboratory abnormalities, in general, do not present significant alterations. Patients with GBS must have cerebrospinal fluid (CSF) collection for analysis.

Engineered IgG1-Fc--one fragment to bind them all.

SummaryThe crystallizable fragment (Fc) of the immunoglobulin class G (IgG) is a very attractive scaffold for the design of novel therapeutics due to its quality of uniting all essential antibody functions. This article reviews the functionalization of this homodimeric glycoprotein by diversification of structural loops of CH3 domains for the design of Fcabs, i.e. antigen‐binding Fc proteins. It reports the design of libraries for the selection of nanomolar binders with wildtype‐like in vivo half‐life and correlation of Fc receptor binding and ADCC. The in vitro and preclinical biological activity of selected Fcabs is compared with that of clinically approved antibodies. Recently, the great potential of the scaffold for the development of therapeutics for clinical use has been shown when the HER2‐binding Fcab FS102 entered clinical phase I. Furthermore, methods for the engineering of biophysical properties of Fcabs applicable to proteins in general are presented as well as the different approaches in the design of heterodimeric Fc‐based scaffolds used in the generation of bispecific monoclonal antibodies. Finally, this work critically analyzes and compares the various efforts in the design of highly diverse and functional libraries that have been made in the engineering of IgG1‐Fc and structurally similar scaffolds.

Human Immunoglobulin Class G (IgG)) Antibody Detection With Photonic Crystal Fiber

Dye-free antibodies were identified in a less than 5-nL volume with a solid-core photonic crystal fiber (SC-PCF). The all-silica fiber contained micrometer-sized features with a 3- ${\mathbf {\mu }}$ m diameter core supported by a steering wheel-shaped lattice. These structures can be employed to monitor the presence of immunobased assays and susceptible secondary antigens specific to the detection application. A 0.8-m section of SC-PCF was filled with a 4.47-nL antibody sample and a LED light source in the 1300 $\text{-}$ 1700 nm range was employed. Although similar sensing configurations exist, the novelty of this investigation is the detection of this particular antibody. This experiment uniquely investigates the spectral characteristics of purified human immunoglobulin class G (IgG) (format-UNLB) in aqueous media. The absorption spectra for the monoclonal antibodies were collected with a conventional optical spectrum analyzer. The antibody solution exhibited two distinct absorption peaks, a water-linked absorption peak between 1400 and 1470 nm, with a maximum absorption power of 1.65 nW, and an antibody-linked absorption peak between 1485 and 1590 nm, with a maximum absorption power of 3.2 nW.

Clinical utility of quantitative multi-antibody Polycheck immunoassays in the diagnosis of coeliac disease.

To evaluate the clinical utility of multi-antibody strategies in the diagnosis of coeliac disease (CD), the new quantitative Polycheck immunoassays were analysed. Polycheck Celiac Panels (PCPs) are immunoenzyme screening assays for the quantitative measurement of coeliac-specific immunoglobulin class G (IgG) or class A (IgA) in serum. Lines of relevant antigens are coated together with five IgG or IgA standard lines used for the standard curve as positive control. PCP IgA consists of human recombinant human tissue transglutaminase (tTG) and deamidated gliadin peptides (DGP) as targets to detect IgA antibodies. PCP IgG consists of tTG, DGP and IF (intrinsic factor) antigens to detect antibodies in IgG class. PCPs were performed on 50 CD patients, including 6 cases with selective IgA deficiency, and 50 non-coeliac controls. CD diagnosis was performed according to the ESPGHAN recommendations: The presence of specific anti-tTG-IgA or anti-DGP-IgG (in the case of IgA deficiency) antibodies, typical histopathological changes in duodenal mucosa described in Marsh-Oberhüber classification as at least grade 2. The diagnosis of the majority of the control subjects was functional gastrointestinal disorders. The PCP results were compared with reference EliA Celikey. The usage of PCPs led to the correct identification of all CD patients. In our study, PCPs showed 100% agreement with the histopathological results. PCP IgA test showed a 98% concordance and correlated positively (R = 0.651, P = 0.0014) with EliA Celikey test. The highest specificity and positive predictive value (both 100%) were observed for the detection of Polycheck anti-tTG-IgA antibodies. The highest sensitivity and negative predictive value (both 100%) were achieved by Polycheck anti-DGP-IgG antibody detection. The best performance (98% sensitivity and negative predictive value, 100% specificity and positive predictive value, diagnostic accuracy - AU ROC 99%) was observed for the strategy of using both PCP IgA and IgG and determining positive outcomes of the test with two or more coeliac-specific antibodies detected. The majority of coeliac patients had multiple antibodies. All four antibodies were detected in 7 (14%) cases, 19 children (38%) were positive for three antibodies and 23 (46%) were positive for two antibodies. The present study showed that detection of coeliac-specific antibodies with multi-antibody PCPs is effective and efficacious in the diagnosis of CD.

Anti-alpha-fodrin antibodies in patients with Sjögren’s syndrome secondary to rheumatoid arthritis

Introduction: The Sjogren's syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration. The currently most researched antibodies for its diagnosis are anti-La and anti-Ro, which, however, have low specificity in the case of SS secondary to rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). The antibodies against alpha-fodrin (AF) have been proposed to diagnose SS. Objective: In the present study, we investigated the anti-AF antibody in a group of RA patients with and without secondary SS (sSS). Methods: Were studied 90 consecutive patients with RA (48.8% of them with SS), and samples of 45 healthy volunteers. Anti-AF immunoglobulin class G (IgG) and anti-AF immunoglobulin class A (IgA) were investigated by enzyme-linked immunosorbent assay (ELISA) and were considered positive when >15 U/ml. Demographic, clinical, and serological data were obtained from chart reviews. Results: Anti-AF IgA was positive in 46/90 (51.1%) of the RA sample and 3/45 (6.7%) of controls (p < 0.001); anti-AF IgG was found in 21/90 (23.3%) of RA patients and none of controls (p = 0.037). Neither IgA nor IgG anti-AF antibodies showed significant difference in patients with and without sSS. Conclusion: In our study, anti-AF IgA and anti-AF IgG neither alloweded diagnosis of sSS in RA patients, nor marked any special clinical or serological finding.

Anti-ADAMTS13 autoantibodies in patients with thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a disorder caused by excessive platelet aggregation in multiple organs. Unless the patients are treated with plasma exchange, this disorder leads to early death. Recent studies show that TTP is caused by deficiency of a plasma metalloprotease ADAMTS13, which specifically cleaves von Willebrand factor (VWF). In the absence of ADAMTS13, unusually large VWF multimers (UL-VWFMs) released from endothelial cells are not cleaved appropriately, and cause platelet-rich microvascular thrombosis under high shear stress. Deficiency of ADAMTS13 is caused by autoantibodies against ADAMTS13 in patients with acquired TTP and mutations of the ADAMTS13 gene in congenital TTP. ADAMTS13 antibodies may inhibit enzymatic function or clear ADAMTS13 from circulation. Anti-ADAMTS13 antibodies are comprised predominantly of immunoglobulin class G (IgG). Epitope mapping studies showed that antibodies direct towards the spacer domain of ADAMTS13 are present in most patients with acquired TTP. The Spacer domain contributes to the binding of ADAMTS13 to unfolded VWF. Plasma exchange therapy for acquired TTP is effective because of removing ADAMTS13 autoantibodies and UL-VWFMs, and supply of ADAMTS13. In addition to plasma exchange, corticostroids are usually used for reducing the production of anti-ADAMTS13 antibodies. Recent studies have shown benefit in using rituximab as a first line therapy of acute acquired TTP.