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Background: Infectious diseases remain a major cause of morbidity and mortality after hematopoietic cell transplantation (HCT). Secondary hypogammaglobulinemia is a risk factor for infectious diseases. Total immunoglobulin G (IgG) levels and the history of infectious diseases are an integral part of determining the indication for immunoglobulin replacement therapy. The clinical significance of IgG2 levels is not well established. Guidelines recommend using pathogen‐specific IgG to evaluate patients with potential secondary immunodeficiency. However, it is difficult in practice to perform such testing. IgG2 may correlate well with pathogen‐specific IgG but the clinical significance of IgG2 is not well established. Methods: To assess the prevalence of low IgG2 levels with normal IgG after HCT, we cross‐sectionally measured the levels of several immunoglobulins, including IgG, IgA, IgM, and IgG2, after HCT, and we assessed the correlation between them. Results: Among 121 patients who underwent cross‐sectional measurements of IgG, IgA, IgM, and IgG2 levels after HCT, 114 had normal IgG2 levels (normal IgG2 group, ≥ 100 mg/dL) and 7 had low IgG2 levels (low IgG2 group, < 100 mg/dL). These 7 patients were allogeneic HCT recipients. All 7 patients with low IgG2 had cGVHD and 4/7 patients had normal total IgG levels. Conclusion: IgG2 levels may be low even in patients with normal IgG levels years after allogeneic HCT. Therefore, our study suggests that when patients develop infectious diseases, especially multiple episodes, it is recommended to measure IgG2 levels to exclude the possibility of secondary hypogammaglobulinemia after allogeneic HCT. [ABSTRACT FROM AUTHOR]

• Decreased IgG2 is associated with thrombocytopenia in influenza infected patients. • Decreased platelet counts predict poor outcomes of influenza infected patients. • IgG2 reduction and d -dimer elevation can better predict influenza related mortality. Thrombocytopenia is a common disorder during influenza that is related to high mortality. A prospective study was performed to investigate the association of immunoglobulin subclass changes accompanying incident thrombocytopenia with clinical outcomes in patients with severe influenza. 96 influenza patients were recruited and divided into two groups, patients with thrombocytopenia (n = 30) and patients without thrombocytopenia (n = 66). Plasma microarrays were used for quantitative analysis of immunoglobulins. The endpoint was 28-day mortality. Continuous platelet count, d -dimer, level of each Ig subclass and other variables were compared between the two groups. Kaplan-Meier curve was taken to analyze the 28-day survival rate of the two groups and Cox regression analysis was performed to identify variables independently associated with 28-day mortality. Patients with thrombocytopenia had significantly high values of d -dimer at admission and when platelet lowest with high SOFA score. Their IgA2, IgG2, and IgG4 values were also lower than those without thrombocytopenia. Patients without thrombocytopenia had a higher 28-day survival rate than those in the thrombocytopenia group. In the multivariate Cox regression model, age (HR = 1.036, 95%CI = 1.011–1.062), IgG2 (HR = 0.990, 95%CI = 0.982–0.998), platelet minimum within 28 days (HR = 0.991, 95%CI = 0.982–0.999) and d -dimer when platelet lowest (HR = 1.091, 95%CI = 1.047–1.137) were independently related to 28-day mortality. Decreased IgG2 may be associated with thrombocytopenia. A coexistence of thrombocytopenia, IgG2 reduction and d -dimer elevation may improve the accuracy of mortality prediction in patients with influenza pneumonia. [ABSTRACT FROM AUTHOR]

Objectives: Visceral leishmaniasis (VL) represents the most severe form of Leishmaniasis infection, often resulting in fatality without timely treatment. Previous studies have found that immunosuppression increases the risk of VL disease progression and mortality, and the total immunoglobulin G (IgG) levels in peripheral blood vary before and after treatment. However, the distinct levels and roles of IgG subclasses in VL have not been documented yet. This study aims to elucidate the characteristics and clinical significance of IgG subclasses in VL. Methods: A total of 43 cases newly‐diagnosed with VL were enrolled in the cohort. We measured the levels of IgG subclasses before and after standard treatment and conducted assessments of bone marrow features. In addition, we analysed other haematological indices and examined the variations in IgG subclasses, as well as their correlation with clinical and laboratory factors. Results: The levels of total IgG, IgG1, and the ratios of both IgG1/IgG and IgG1/IgG2 decreased significantly after treatment, whereas the ratios of IgG2/ IgG showed an obvious increase. The VL patients without hyperglobulinemia displayed significant lower IgG1/IgG2 ratios, but higher IgG2/IgG ratios compared with those with hyperglobulinemia. In addition, VL patients with positive bone marrow amastigotes had significant higher IgG1/IgG and IgG1/IgG2 ratios, but lower IgG2/IgG ratios. IgG subclasses were correlated with abnormal blood test results, particularly immunological elements including IgM and Complement 4 (C4). Conclusions: IgG1 and IgG2 exhibited contrasting changes after treatment in VL patients. The features of bone marrow and laboratory tests indicated that IgG1 and IgG2 serve different roles in the progression of VL. The ratios of IgG subclasses may be more precise indicators to evaluate immune reaction in VL than traditional total IgG. [ABSTRACT FROM AUTHOR]

Development of a universal influenza vaccine that can provide robust and long-lasting protection against heterologous infections is a global public health priority. A variety of vaccine antigens are designed to increase the antigenicity of conserved epitopes to elicit cross-protective antibodies that often lack virus-neutralizing activity. Given the contribution of antibody effector functions to cross-protection, adjuvants need to be added to modulate antibody effector functions as well as to enhance antibody quantity. We previously showed that post-fusion influenza vaccine antigens elicit non-neutralizing but cross-protective antibodies against conserved epitopes. Here, using a murine model, we comparably assessed the adjuvanticity of the newly developed SA-2 adjuvant containing a synthetic TLR7 agonist DSP-0546 and squalene-based MF59 analog as representative Th1- or Th2-type adjuvants, respectively. Both types of adjuvants in the post-fusion vaccine comparably enhanced cross-reactive IgG titers against heterologous strains. However, only SA-2 skewed the IgG subclass into the IgG2c subclass in association to its Th1-polarizing nature. SA-2-enhanced IgG2c responses exhibited antibody-dependent cellular cytotoxicity against heterologous virus strains, without cross-neutralizing activity. Eventually, the SA-2-adjuvanted vaccination provided protection against lethal infection by heterologous H3N2 and H1N1 viruses. Together, we conclude that the combination with a SA-2 is advantageous for enhancing the cross-protective capability of post-fusion HA vaccines that elicit non-neutralizing IgG antibodies. [ABSTRACT FROM AUTHOR]

Objective To assess the role of the anti-TIF1γ auto-antibody (aAb) IgG2 isotype as a biomarker of cancer in anti-TIF1γ aAb-positive adult DM. Methods International multicentre retrospective study with the following inclusion criteria: (i) diagnosis of DM according to ENMC criteria; (ii) presence of anti-TIF1γ IgG aAb determined using an in-house addressable laser bead immunoassay (ALBIA) from cryopreserved serums sampled at time of DM diagnosis and (iii) available baseline characteristics and follow-up data until the occurrence of cancer and/or a minimum follow-up of 1 year for patients without known cancer at diagnosis. Detection and quantification of anti-TIF1γ IgG2 aAb was done using the in-house ALBIA. In addition, a recent ELISA commercial kit was used for anti-TIF1γ IgG aAb quantification. Results A total of 132 patients (mean age 55±15 years) of whom 72 (54.5%) had an associated cancer were analysed. The association between the presence of cancer and the presence of anti-TIF1γ IgG2 aAb was statistically significant (P  = 0.026), with an OR of 2.26 (95% CI: 1.10, 4.76). Patients with cancer displayed significantly higher anti-TIF1γ IgG2 aAb ALBIA values with a median value of 1.15 AU/ml (IQR: 0.14–9.76) compared with 0.50 AU/ml (IQR: 0.14–1.46) for patients without cancer (P  = 0.042). In addition, patients with cancer displayed significantly higher anti-TIF1γ IgG aAb ELISA values with a median value of 127.5 AU/ml (IQR: 81.5–139.6) compared with 93.0 AU/ml (IQR: 54.0–132.9) for patients without cancer (P  = 0.004). Conclusion These results suggest considering anti-TIF1γ IgG2 ALBIA and IgG ELISA values as biomarkers of cancer in anti-TIF1 γ aAb-positive adult DM. [ABSTRACT FROM AUTHOR]

Females often exhibit superior immune responses compared to males toward vaccines and pathogens such as influenza viruses and SARS-CoV-2. To help explain these differences, we first studied serum immunoglobulin isotype patterns in C57BL/6 male and female mice. We focused on IgG2b, an isotype that lends to virus control and that has been previously shown to be elevated in murine females compared to males. Improvements in IgG2b serum levels, and/or IgG2b ratios with other non-IgM isotypes, were observed when: (i) wildtype (WT) female mice were compared to estrogen receptor knockout mice (IgG2b, IgG2b/IgG3, IgG2b/IgG1, and IgG2b/IgA were all higher in WT mice), (ii) unmanipulated female mice were compared to ovariectomized mice (IgG2b/IgA was higher in unmanipulated animals), (iii) female mice were supplemented with estrogen in the context of an inflammatory insult (IgG2b and IgG2b/IgG3 were improved by estrogen supplementation), and (iv) male mice were supplemented with testosterone, a hormone that can convert to estrogen in vivo (IgG2b, IgG2b/IgG3, IgG2b/IgG1, and IgG2b/IgA were all improved by supplementation). We next examined data from three sets of previously described male and female human blood samples. In each case, there were higher IgG2 levels, and/or ratios of IgG2 with non-IgM isotypes, in human females compared to males. The effects of sex and sex hormones in the mouse and human studies were subtle, but frequent, suggesting that sex hormones represent only a fraction of the factors that influence isotype patterns. Examination of the gene loci suggested that upregulation of murine IgG2b or human IgG2 could be mediated by estrogen receptor binding to estrogen response elements and cytosine-adenine (CA) repeats upstream of respective Cγ genes. Given that murine IgG2b and human IgG2 lend to virus control, the isotype biases in females may be sufficient to improve outcomes following vaccination or infection. Future attention to sex hormone levels, and consequent immunoglobulin isotype patterns, in clinical trials are encouraged to support the optimization of vaccine and drug products for male and female hosts. [ABSTRACT FROM AUTHOR]

ObjectiveGiven the emerging appreciation for the role of antibody-dependent effector functions and IgG subclass distribution among spontaneous controllers of HIV, we sought to determine whether antibody-associated features diverged in early HIV infection between patients who ultimately became controllers versus those who became progressors.MethodsIgG was purified from plasma from nine acutely infected patients who subsequently controlled HIV spontaneously (controllers) and 10 acutely infected individuals who did not control viremia (progressors). Antibody profiles were compared at weeks 4, 12, 24 and 48 postinfection. Levels of clade B gp120-specific, gp140-specific and gp41-specific IgG antibody subclasses were measured. In addition, gp120-specific antibody-dependent cellular phagocytosis, rapid fluorescent antibody-dependent cellular cytotoxicity and antibody-dependent cellular viral inhibition were all assessed.ResultsAlthough no single antibody-related measurement was significantly associated with long-term HIV control, combinations of antibody-associated variables were able to accurately differentiate controllers and progressors. In contrast to controllers, progressors showed greater dynamic changes in gp120-specific subclass selection profiles, with increasing levels of Env-specific IgG2 antibodies and losses in Env-specific IgG3 antibodies. Moreover, progressors, but not controllers, lost antibody-dependent cellular viral inhibition function over time. Together, these results highlight changes in IgG subclass selection profiles in progressive, but not controlled, HIV infection.ConclusionThis study suggests that the temporal variation and maintenance of Env-specific IgG subclasses during acute HIV infection are predictive of eventual disease control. The maintenance of gp120-specific and gp140-specific IgG3 may contribute to control of disease in spontaneous controllers. Thus, strategies to induce stable IgG3 responses may preserve control of the viral reservoir.

Keywords: house dust mites; IgG2; IgG4; specific behaviour of high responders; sublingual immunotherapy; vitamin D EN house dust mites IgG2 IgG4 specific behaviour of high responders sublingual immunotherapy vitamin D 1219 1224 6 10/13/22 20221001 NES 221001 Key messages Seric vitamin D is not a predictive marker of allergy immunotherapy (AIT) efficacy. Indeed, the latter display correlated levels of serum vitamin D before treatment, on the on hand, and of allergen-specific IgG4 and IgG2 before and/or after treatment, on the other hand. As an illustration, serum levels of vitamin D before treatment were plotted against serum levels of I D. pteronyssinus i -specific IgG4, as measured in high and low responders before treatment (Figure 1D,E, respectively) and after treatment (Figure 1F,G, respectively). Moreover, statistically significant positive correlations occurred in high responders only, between, on the one hand, the serum concentration of vitamin D before treatment and, on the other hand, the serum concentrations of HDM-specific IgG4 and IgG2 before and/or after treatment (Table 1). [Extracted from the article]

Abstract Although extensive research has been performed on bovine non-aureus staphylococci (NAS), several aspects such as bacteria-host interaction remain largely unstudied. Moreover, only a few mastitis pathogen challenge studies in cows have been conducted in the dry period, an important period that allows intramammary infection (IMI) to cure and new IMI to occur. We challenged 16 quarters of 4 Holstein Friesian cows at dry off with 100; 100 000 or 10 000 000 CFU of the udder-adapted S. chromogenes IM strain. Four quarters from one cow served as negative controls. Internally sealed quarters remained untouched, whereas non-sealed quarters were sampled 3 times during the dry period. After parturition, colostrum and daily milk samples were taken during the first week of lactation of all quarters. In total, 8 quarters appeared to be colonized, since S. chromogenes IM was recovered at least once during the experiment, as substantiated using Multilocus Sequence Typing. S. chromogenes IM shedding was highest in dry quarters inoculated with 10 000 000 CFU. Colonized quarters had the highest quarter somatic cell count (qSCC) in early lactation. Inoculated quarters (both colonized and non-colonized) had lower IL-6 and IL-10 concentrations in the dry period, whilst IFN-γ levels tended to be higher in colonized quarters compared to non-inoculated quarters. Also, IgG2 levels were higher in inoculated compared to non-inoculated quarters and the IgG2/IgG1 ratio was on average above 1. To conclude, we showed that dry quarters can be colonized with S. chromogenes IM, resulting in a shift towards a Th1 response in late gestation and early lactation characterised by an increased IgG2 concentration. However, further research is needed to confirm our findings.

T follicular helper (Tfh) cells are critical in providing help for B cells in the germinal center reaction. Tfh cell plasticity, especially with regard to their expression of effector Th cytokines, has been described, but lacks in-depth analysis with genetic approaches. In this study, we systemically compared transcriptomic profiles of Tfh cells derived from various types of immune responses and found gene clusters corresponding to effector Th cells were differentially induced in response to pathogens or immune responses. Of special interest, a subset of Tfh cells producing IFN-γ was generated in an influenza virus infection, partially dependent on the innate cytokine IL-12. Lineage-tracing mouse model revealed unique developmental regulation of IFN-γ+ Tfh cells, while selective ablation of these cells impaired the induction of IgG2c+ germinal center B cells and the control of influenza infection. These results indicate that pathogen-associated Tfh cell plasticity is necessary for host immunity, which has implications in vaccine design. [ABSTRACT FROM AUTHOR]

Abstract Background Factors associated with IgG levels in adults with IgG subclass deficiency (IgGSD) are incompletely understood. We studied adults with IgGSD with subnormal IgG1 only, subnormal IgG1/IgG3, or subnormal IgG3 only without other subnormal IgG subclasses, IgA, or IgM. We compiled: age; sex; autoimmune condition(s) (AC); atopy; IgG, IgG subclasses, IgA, IgM; IgGsum (IgG1 + IgG2 + IgG3 + IgG4); and D (percentage difference between IgGsum and IgG). We compared attributes of patients with/without subnormal IgG (

Background: In this study, we determined the accuracy of anti-Leishmania IgG and IgG subclasses to distinguish clinical forms of American tegumentary leishmaniasis (ATL) and and determined the relationship between antibodies levels with cytokine production and severity of ATL. Methods: Participants were 40 patients with cutaneous leishmaniasis (CL), 20 patients with mucosal leishmaniasis (ML), 20 patients with disseminated leishmaniasis (DL), and 20 individuals with subclinical Leishmania braziliensis infection (SC). Diagnosis was performed by DNA of L. braziliensis or IFN-γ production in SC. IgG and subclasses of IgG to soluble Leishmania antigen and cytokine levels in supernatants of mononuclear cells were detected by ELISA. Results: IgG was detected in 95%, 95%, and 100% of patients with CL, ML, and DL, respectively. Higher levels of anti-Leishmania IgG and IgG2 were seen in DL compared to CL, ML, and SC. ROC analysis confirmed the ability of IgG to distinguish DL from the other clinical forms. A direct correlation was observed between IgG titers and levels of IFN-γ and CXCL10 in CL and DL, and IgG2 antibodies were correlated with the number of lesions in DL. Conclusions: High anti-Leishmania IgG and IgG2 levels are characteristic of DL, and while IgG was correlated with pro-inflammatory cytokines, IgG2 was direct correlated with the number of lesions.

Background and Objective: Whether immunological biomarkers combined with clinical characteristics measured during an exacerbation-free period are predictive of acute exacerbation of chronic obstructive pulmonary disease (AECOPD) frequency and severity is unknown. Method: We measured immunological biomarkers and clinical characteristics in 271 stable chronic obstructive pulmonary disease (COPD) patients (67% male, mean age 63 years) from "The Obstructive Pulmonary Disease Outcomes Cohort of Switzerland" cohort on a single occasion. One-year follow-up data were available for 178 patients. Variables independently associated with AECOPD frequency and severity were identified by multivariable regression analyses. Receiver operating characteristic analysis was used to obtain optimal cutoff levels and measure the area under the curve (AUC) in order to assess if baseline data can be used to predict future AECOPD. Results: Higher number of COPD medications (adjusted incident rate ratio [aIRR] 1.17) and platelet count (aIRR 1.03), and lower FEV1% predicted (aIRR 0.84) and IgG2 (aIRR 0.84) were independently associated with AECOPD frequency in the year before baseline. Optimal cutoff levels for experiencing frequent (>1) AECOPD were ≥3 COPD medications (AUC = 0.72), FEV1 ≤40% predicted (AUC = 0.72), and IgG2 ≤2.6 g/L (AUC = 0.64). The performance of a model using clinical and biomarker parameters to predict future, frequent AECOPD events in the same patients was fair (AUC = 0.78) but not superior to a model using only clinical parameters (AUC = 0.79). The IFN-lambda rs8099917GG-genotype was more prevalent in patients who had severe AECOPD. Conclusions: Clinical and biomarker parameters assessed at a single point in time correlated with the frequency of AECOPD events during the year before and the year after assessment. However, only clinical parameters had fair discriminatory power in identifying patients likely to experience frequent AECOPD. [ABSTRACT FROM AUTHOR]

Background: IgG2 responses are associated with repeated antigen exposure and display highly mutated variable domains. A recent study highlighted a role of IgG2+ memory B cells and allergen‐specific IgG2 levels after a 3rd consecutive pre‐seasonal sublingual allergen immunotherapy (AIT) with grass pollen tablet. Herein, we aim to explore changes in allergen‐specific IgG2 in individuals undergoing house dust mite immunotherapy (HDM‐AIT) and explore whether the interrelationship with other humoral responses (i.e., IgG4 and IgE) may discriminate between high and low responders. Methods: Levels of serum Dermatophagoides pteronyssinus and Dermatophagoides farinae‐specific IgG2, IgG4, and IgE antibodies were measured by ELISA or ImmunoCap in a sub‐group of individuals enrolled in a randomized, double‐blind, placebo‐controlled, sublingual AIT study evaluating the safety and efficacy of a 300 IR HDM tablet. Results: After 1‐year sublingual AIT, HDM‐specific serum IgG2 responses increase mostly in high versus low responders and are distinctive according to the clinical benefit. Higher correlation between HDM‐specific IgG2, IgE, and/or IgG4 responses is seen in subjects benefiting the most from HDM‐AIT as indicated by changes in Average Total Combined Scores. More strikingly, statistically significant correlation between HDM‐specific IgG2 and IgE responses is only observed in individuals stratified as high responders. Conclusions: We provide evidence for coordinated serum immune responses upon AIT in HDM‐allergic subjects exhibiting high clinical benefit when compared with low responders. Assessing HDM‐specific IgE, IgG2, and IgG4 in serum could be used as follow‐up combined markers to support decision as to AIT continuation and/or adaptation. [ABSTRACT FROM AUTHOR]

IgG4‐Related Disease (IgG4‐RD) results from tissue infiltration by IgG4‐expressing plasma cells and lymphocytes, leading to fibrosis and organomegaly. Clinical presentation is remarkably variable according to organ involvement, and high IgG4 serum concentration, initially considered a diagnostic hallmark of IgG4‐RD, tends to be forgone as an indispensable criterion for its diagnosis; it can indeed be absent in some patients, highlighting the diversity of presentation of this dysimmune condition. Nevertheless, elevation of IgG4 serum concentration in suggestive settings remains an argument in favour of IgG4‐RD, and while other IgG subclasses can be elevated, this biological feature lacks any diagnostic value. We retrospectively studied 9 patients (5 females, 4 males, 31–81 years old) for whom a diagnosis of IgG4‐RD had been considered, based on clinical, imaging or histological criteria, but appeared to display abnormally high serum IgG2 while IgG4 levels were normal. Increased serum IgG1 in one case and increased IgG3 in another one were also noticed. Immunohistochemical analyses of intracellular immunoglobulins could be performed on tissue lymph node biopsies from 2 patients, which demonstrated strong infiltration with IgG2‐expressing plasma cells. Thus, overexpression of IgG2 subclass may highlight cases of dysimmune disorders resembling IgG4‐RD, although the disease trigger might be different, notably infectious. We suggest measuring all serum IgG subclass levels in patients with features consistent with IgG4‐RD. [ABSTRACT FROM AUTHOR]

Henok Andualem,1 Mulugeta Kiros,2 Sisay Getu,3 Wasihun Hailemichael1 1Immunology and Molecular Biology, Department of Medical Laboratory Science, College of Health Science, Debre Tabor University, Debre Tabor, Ethiopia; 2Medical Microbiology, Department of Medical Laboratory Science, College of Health Science, Debre Tabor University, Debre Tabor, Ethiopia; 3Clinical Hematology and Immunohematology, Department of Medical Laboratory Science, College of Health Science, Debre Tabor University, Debre Tabor, EthiopiaCorrespondence: Henok AndualemImmunology and Molecular Biology, Department of Medical Laboratory Science, College of Health Science, Debre Tabor University, Debre Tabor, EthiopiaTel +251923251524Email henokyaa@yahoo.comAbstract: The global threat of COVID-19 is continued with no commercially available vaccine or drug yet. While the application of convalescent therapy is usually beneficial, for critically ill patients, the detrimental effect associated with some antibodies is also reported. The immunoglobulin G (IgG) antibody in response to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is described, albeit the lack of defining whether the difference in subclasses has a beneficial or detrimental role. IgG2 has limited ability to activate innate immune cells and complement-mediated inflammation, which have been inversely described in SARS-CoV-2 pathogenesis. The expansion of IgG2 is promoted by interferon γ (IFN-γ); however, there is a low level of IFN-γ in COVID-19 patients. Therefore, this review describes the importance of targeting IgG2, with IFN-γ in minimizing the SARS-CoV-2 associated inflammation, and may provide insight into the design of vaccine or antibody-based therapies to COVID-19 disease.Keywords: IgG2, IFN-γ, antibody therapy, COVID-19 vaccine

Although extensive research has been performed on bovine non-aureus staphylococci (NAS), several aspects such as bacteria-host interaction remain largely unstudied. Moreover, only a few mastitis pathogen challenge studies in cows have been conducted in the dry period, an important period that allows intramammary infection (IMI) to cure and new IMI to occur. We challenged 16 quarters of 4 Holstein Friesian cows at dry off with 100; 100 000 or 10 000 000 CFU of the udder-adapted S. chromogenes IM strain. Four quarters from one cow served as negative controls. Internally sealed quarters remained untouched, whereas non-sealed quarters were sampled 3 times during the dry period. After parturition, colostrum and daily milk samples were taken during the first week of lactation of all quarters. In total, 8 quarters appeared to be colonized, since S. chromogenes IM was recovered at least once during the experiment, as substantiated using Multilocus Sequence Typing. S. chromogenes IM shedding was highest in dry quarters inoculated with 10 000 000 CFU. Colonized quarters had the highest quarter somatic cell count (qSCC) in early lactation. Inoculated quarters (both colonized and non-colonized) had lower IL-6 and IL-10 concentrations in the dry period, whilst IFN-γ levels tended to be higher in colonized quarters compared to non-inoculated quarters. Also, IgG2 levels were higher in inoculated compared to non-inoculated quarters and the IgG2/IgG1 ratio was on average above 1. To conclude, we showed that dry quarters can be colonized with S. chromogenes IM, resulting in a shift towards a Th1 response in late gestation and early lactation characterised by an increased IgG2 concentration. However, further research is needed to confirm our findings. [ABSTRACT FROM AUTHOR]

Background: Factors associated with IgG levels in adults with IgG subclass deficiency (IgGSD) are incompletely understood. We studied adults with IgGSD with subnormal IgG1 only, subnormal IgG1/IgG3, or subnormal IgG3 only without other subnormal IgG subclasses, IgA, or IgM. We compiled: age; sex; autoimmune condition(s) (AC); atopy; IgG, IgG subclasses, IgA, IgM; IgGsum (IgG1 + IgG2 + IgG3 + IgG4); and D (percentage difference between IgGsum and IgG). We compared attributes of patients with/without subnormal IgG (< 7.00 g/L; subnormal IgG1 subclass groups only) and analyzed IgGsum and IgG relationships. We performed backward stepwise regressions on IgG using independent variables IgG subclasses, age, and sex and on D using independent variables age and sex. Results: There were 39 patients with subnormal IgG1 only (89.7% women), 53 with subnormal IgG1/IgG3 (88.7% women), and 115 with subnormal IgG3 only (91.3% women). Fifteen patients (38.5%) and 32 patients (60.4%) in the respective subnormal IgG1 subclass groups had subnormal IgG. Attributes of patients with/without IgG < 7.00 g/L were similar, except that AC prevalence was lower in patients with subnormal IgG1 only and IgG < 7.00 g/L than ≥ 7.00 g/L (p = 0.0484). Mean/median IgG1 and IgG2 were significantly lower in patients with IgG < 7.00 g/L in both subnormal IgG1 subclass groups (p < 0.0001, all comparisons). Regressions on IgG in three subclass groups revealed positive associations with IgG1 and IgG2 (p < 0.0001 each association). Regressions on D revealed no significant association. IgG1 percentages of IgGsum were lower and IgG2 percentages were higher in patients with subnormal IgG1 subclass levels than subnormal IgG3 only (p < 0.0001 all comparisons). Conclusions: We conclude that both IgG1 and IgG2 are major determinants of IgG in patients with subnormal IgG1, combined subnormal IgG1/IgG3, or subnormal IgG3 and that in patients with subnormal IgG1 or combined subnormal IgG1/IgG3, median IgG2 levels are significantly lower in those with IgG < 7.00 g/L than those with IgG ≥ 7.00 g/L. [ABSTRACT FROM AUTHOR]

Circulating autoantibodies of IgG2 isotype predominate in Systemic Lupus Erythematosus (SLE) and concur to the development of the renal lesions characteristic of Lupus Nephritis (LN). Anti-dsDNA and anti-histones IgG2, together with anti-podocyte proteins (i.e., α-enolase) are the major autoantibodies in serum and renal glomeruli of LN patients. The mechanisms underlying autoantibody formation and isotype switching in SLE and LN are unknown. A major issue is how DNA/histones are externalized from cell nucleus, driving the autoimmune response. Neutrophil Extracellular Traps (NETs) have been recently identified as crucial players in this context, representing the main source of DNA and nucleosome proteins. A second key point is what regulates IgG2 isotype switching: in mouse models, T-bet transcription factor has been described as essential for IgG2a class switch. We hypothesized that, in SLE, NET formation is the key mechanism responsible for externalization of autoantigens (i.e., dsDNA, histones 2,3, and α-enolase) and that T-bet is upregulated by NETs, driving, in this way, immunoglobulin class switch recombination (CSR), with production of IgG2 autoantibodies. The data here presented show that NETs, purified from SLE patients, stimulate ex vivo IgG2 isotype class switch possibly through the induction of T-bet. Of note, we observed a prominent effect of NETs on the release of soluble IgG2 in SLE patients', but not in healthy donors' B cells. Our results add important knowledge on the mechanisms of IgG2 class switch in SLE and contribute to further elucidate the role of NETs in LN pathogenesis.

• Anti-Leishmania IgG is a marker of disseminated leishmaniasis. • Anti-Leishmania IgG correlates with Th1 immune response in disseminated leishmaniasis. • Anti-Leishmania IgG2 correlates with the number of lesions in disseminated leishmaniasis. In this study, we determined the accuracy of anti- Leishmania IgG and IgG subclasses to distinguish clinical forms of American tegumentary leishmaniasis (ATL) and and determined the relationship between antibodies levels with cytokine production and severity of ATL. Participants were 40 patients with cutaneous leishmaniasis (CL), 20 patients with mucosal leishmaniasis (ML), 20 patients with disseminated leishmaniasis (DL), and 20 individuals with subclinical Leishmania braziliensis infection (SC). Diagnosis was performed by DNA of L. braziliensis or IFN-γ production in SC. IgG and subclasses of IgG to soluble Leishmania antigen and cytokine levels in supernatants of mononuclear cells were detected by ELISA. IgG was detected in 95%, 95%, and 100% of patients with CL, ML, and DL, respectively. Higher levels of anti- Leishmania IgG and IgG2 were seen in DL compared to CL, ML, and SC. ROC analysis confirmed the ability of IgG to distinguish DL from the other clinical forms. A direct correlation was observed between IgG titers and levels of IFN-γ and CXCL10 in CL and DL, and IgG2 antibodies were correlated with the number of lesions in DL. High anti -Leishmania IgG and IgG2 levels are characteristic of DL, and while IgG was correlated with pro-inflammatory cytokines, IgG2 was direct correlated with the number of lesions. [ABSTRACT FROM AUTHOR]

Background.: Immunoglobulin (Ig) G4-related diseases (RDs) are systemic diseases in which serum IgG4 levels are frequently elevated. They can cause diffuse or focal tumor formation, organ swelling, and tissue thickening in organs infiltrated by IgG4 + plasma cells. The diagnostic criteria for IgG4-RDs include an IgG4/IgG ratio >40%, but counting IgG+ cells can be difficult because of the weakness of IgG staining density. We hypothesized that an antibody cocktail of mixed IgG1, IgG2, IgG3, and IgG4 (AC-IgG) might give immunohistochemistry results comparable with those of IgG in IgG4-RD. Methods.: We compared AC-IgG reactivity with IgG expression in type 1 autoimmune pancreatitis (AIP), a representative IgG4-RD. We compared immunohistochemistry results using AC-IgG and IgG-only in 10 cases of AIP. The coefficient of variation (Cv) was used to analyze differences between AC-IgG and IgG findings in AIP by 13 board-certified pathologists. Results.: Although mean values for IgG+ cells did not significantly differ between AC-IgG (34.3; range = 27.4-37.1) and IgG (30.0; range = 23.0-45.6; P =.6254), Cv was lower for AC-IgG (33.4%) than for IgG (51.4%; regression equation; y [IgG] = 0.988 x + 0.982; correlation coefficient = 0.907). The data showed that the results of both methods were largely consistent. Conclusion.: AC-IgG could replace IgG to count IgG+ cells because of its lower Cv. [ABSTRACT FROM AUTHOR]

Cysteinylation is a post-translational modification (PTM) that occurs when a cysteine residue on a protein forms a disulfide bond with a terminal cysteine molecule. This PTM has been found in the hinge region of several recombinant therapeutic IgG2 antibodies, but the impact of cysteinylation on the safety and immunogenicity of therapeutics remains unclear. In this study, we characterized recombinant and endogenous IgG2 antibodies to quantify their levels of hinge cysteinylation, if present. To the best of our knowledge, this is the first study to identify and quantify hinge cysteinylation in endogenous IgG2 antibodies from healthy human serum. We used anti-IgG2 immunopurification of human serum to specifically enrich for endogenous IgG2 antibodies, and then subjected the resulting samples to Lys-C peptide mapping coupled with targeted mass spectrometry techniques. Using this analytical workflow, we found that all healthy human serum samples tested (N = 10) contained quantifiable levels of hinge cysteinylation (0.8 ± 0.3%) in their endogenous human IgG2s (IgG2-A isoform). These findings demonstrate that hinge cysteinylation in therapeutic IgG2s, at least up to a certain level, is well tolerated in humans and pose minimal safety or immunogenicity risks.

House dust mites (HDMs) are among the most important allergen sources containing many different allergenic molecules. Analysis of patients from a double-blind, placebo-controlled allergen-specific immunotherapy (AIT) study indicated that patients may benefit from AIT to different extents depending on their molecular sensitization profiles. Our aim was to investigate in a real-life setting whether stratification of patients with HDM allergy according to molecular analysis may enhance AIT success. Serum and nasal secretion samples from patients with HDM allergy (n = 24) (at baseline, 7, 15, 33, and 52 weeks) who had received 1 year of treatment with a well-defined subcutaneous AIT form (Alutard SQ 510) were tested for IgE and IgG reactivity to 15 microarrayed HDM allergen molecules with ImmunoCAP Immuno-solid-phase Allergen Chip technology. IgG subclass levels to allergens and peptides were determined by ELISA, and IgG blocking was assessed by basophil activation. In vitro parameters were related to reduction of symptoms determined by combined symptom medication score and visual analog scale score. Alutard SQ 510 induced protective IgG mainly against Dermatophagoides pteronyssinus (Der p) 1 and Der p 2 and to a lesser extent to Der p 23, but not to the other important allergens such as Der p 5, Der p 7, and Der p 21, showing better clinical efficacy in patients sensitized only to Der p 1 and/or Der p 2 as compared with patients having additional IgE specificities. Stratification of patients with HDM allergy according to molecular sensitization profiles and molecular monitoring of AIT-induced IgG responses may enhance the success of AIT. [ABSTRACT FROM AUTHOR]

• SLE patients are highly susceptible to pneumococcal infection. • >50% of SLE patients fail to reach immune protection after pneumococcal vaccination. • IgG2 serum level before vaccination is strongly indicative of long-term protection. Systemic lupus erythematosus (SLE) patients are at risk for pneumococcal infection. Twenty-one consecutive SLE patients (40[25–75] years) received the sequential PCV13/PPSV23 vaccine and factors associated with long-term protection were analyzed. Immune protection, defined by an antigen-specific IgG concentration ≥1.3 µg/mL for at least 70% of 7 pneumococcal serotypes was assessed at baseline, 2, 6, 12 and 36 months defining long-term protection. Only 10 patients showed pneumococcal immune protection 36 months after vaccination. Eleven (52.4%) patients had no long-term protection with a seroconversion that never or only transiently occurred. SLE disease features, treatment received and immunological characteristics did not differ between protected and unprotected patients except for the pre-vaccination IgG2 serum levels. Serum IgG2 level >2.125 µg/ml showed a sensitivity of 100% and a specificity of 90.9% for long-term protection. Sequential pneumococcal vaccination conferred poor immune protection in SLE. Baseline IgG2 serum level identified patients able to benefit from pneumococcal vaccination. [ABSTRACT FROM AUTHOR]

Agonistic antibody, ChiLob7/4, anti-CD40, IgG2, disulfide bonds For example, an interesting recent study showed that monoclonal IgA antibodies could be superior for the neutralization of SARS-CoV-2 compared to IgG.[6] In summary, a number of promising tools for the engineering of monoclonal antibodies and their functional effects are on the rise (Figure 2). Keywords: agonistic antibody; anti-CD40; ChiLob7/4; disulfide bonds; IgG2 EN agonistic antibody anti-CD40 ChiLob7/4 disulfide bonds IgG2 1717 1718 2 06/02/23 20230601 NES 230601 Monoclonal antibodies are one of the most important biotechnological tools available. [Extracted from the article]

The diagnosis of angiostrongylus cantonensis meningoencephalitis is established by the presence of the helminth larvae in the cerebrospinal fluid, but this evidence is very difficult to find since the larvae are labile in this medium and are not frequently found. Because in Cuba, the presence of the parasite dates back to 1981 and this parasite is the only one that can cause this disease in the country, a review is carried out with the aim of reviewing the literature published on the subject to collect all the evidence that help the auxiliary diagnosis of eosinophilic meningoencephalitis. It is proposed that the study of the intrathecal synthesis of IgE and C3c, together with the pattern of local synthesis of IgA + IgG mainly and IgG1 + IgG2, are the most indicated. There are other proteins that could help as the intrathecal synthesis of C4 and to a lesser extent MBL.

ABSTRACT In 2011, the human pneumococcal standard reference serum, 007sp, was established as a replacement for the previous standard, lot 89SF, supplies of which were dwindling. The pneumococcal reference serum is used primarily in the standardized pneumococcal enzyme-linked immunosorbent assay (World Health Organization reference enzyme-linked immunosorbent assay) but has also been used in functional assays. Serotype-specific IgG values for 24 pneumococcal capsular serotypes have previously been assigned to 007sp by bridging to the original values derived for lot 89SF. In this study, by bridging to existing values in lot 89SF, we assign weight-based serotype-specific IgA, IgG1, and IgG2 to 007sp for 11 pneumococcal capsular serotypes (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19F, and 23F), as well as serotype 19A-specific IgA. Concentrations for serotype-specific IgA, IgG1, and IgG2 present in 007sp were comparable to those previously assigned to lot 89SF. In addition, the concentration of serotype-specific IgG1 plus IgG2 assigned to 007sp significantly correlated to previously assigned 007sp IgG values. The accuracy of antibody assignments to 007sp from lot 89SF was assessed by comparing the concentration of serotype-specific IgA, IgG1, and IgG2 in 16 unknown samples using both 007sp and lot 89SF as the standard. Interpolated values for the unknown samples were highly correlated with average R2 values of 0.9729, 0.9951, and 0.9933 for IgA, IgG1, and IgG2, respectively, for all serotypes demonstrating the precise nature assignments to 007sp made in this study. Nonparallelism between 007sp and lot 89SF has precluded the derivation of serotype-specific IgM values. IMPORTANCE A well-characterized antibody standard is an indispensable reagent for use in assays designed to measure antibodies with precision and where assays between laboratories need to be comparable. The human pneumococcal standard reference serum, lot 89SF, greatly facilitated the standardization of enzyme-linked immunosorbent assay methodologies during a critical period when the first pneumococcal polysaccharide-conjugate vaccines were being evaluated for licensure. Due to dwindling supplies of lot 89SF, a new reference standard, 007sp, was produced in 2011. Understanding the isotype and subclass composition of either natural or vaccine induced responses to pathogens has assumed increasing importance. In this study, we have assigned IgA, IgG1, and IgG2 values to pneumococcal serotypes 1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F by bridging to existing values in lot 89SF.

• Relapsing-Remitting Multiple Sclerosis (RR-MS) patients treated with glatiramer acetate (GA) generate anti-drug antibodies (ADA) after three months of treatment. • The concentration of total IgG antibodies detected in patients treated with GA did not differ from that in patients treated with IFN-β or healthy volunteers. • The levels of ADA of IgG subclasses detected in patients treated with GA were IgG4>>IgG3>IgG1>IgG2. • Our results suggest the presence of the differential sex-specific pattern of IgG2 and IgG4 subclasses of anti-drug antibodies (ADA) induced by glatiramer acetate in RR-MS patients. • Subclasses IgG2 in female and IgG1 in male patients correlate with IFN-γ serum levels. Besides, IgG class and IgG1 subclass of ADA levels in male patients correlate with IL-10 and IL-6, respectively. Glatiramer acetate (GA) is a drug for Multiple Sclerosis (MS) treatment. However, its administration induces anti-drug antibodies (ADA). This research evaluated the sex differences in humoral response against GA in RR-MS patients We analyzed 69 RR-MS patients, 43 treated with GA and 26 treated with IFN-β. In all cases, the serum concentration of IgG antibodies was determined by UPLC, whereas the levels of IgG subclasses (1–4) of anti-GA antibodies and the concentration of IL-6 were detected by Multiplex and IL-10, and IFN-γ were detected by ELISA. The total concentration of IgG antibodies in patients did not differ between treatments, whereas the IgG levels of ADA were higher in male and female patients treated with GA (P ≤ 0.0001). The subclasses of IgG anti-GA antibodies were as follows: IgG4>>IgG3>IgG1>IgG2. Statistical analysis showed differences in the IgG2 (P ≤ 0.01) and IgG4 (P ≤ 0.0001) subclasses by sex in RR-MS patients. Levels of IgG1 subclass in male patients correlated positively with the circulatory levels of IL-6 (r s = 0.587, P ≤ 0.04) and IFN-γ (r s = 0.721, P ≤ 0.001), while IgG2 subclass levels in female patients correlated with serum levels of IFN-γ (r s = 0.628, P ≤ 0.0006). Statistical analysis did not detect correlations between the levels of IgG (1–4) subclasses of anti-GA antibodies and the evaluated clinical parameters. This study showed differences in the levels of IgG2 and IgG4 subclasses of ADA between male and female RR-MS patients. Further studies are necessary to take advantage of the clinical potential of this finding. [ABSTRACT FROM AUTHOR]

Our previous reported that Jeddah, Saudi Arabia population have a comparable and protective herd immunity represented by IgG, IgA and IgM against Haemophilus influenzae type b (Hib), by using indirect ELISA test was used to evaluate Haemophilus influenzae type b (Hib) anti-polyribosyl-ribitol phosphate (PRP) total antibodies (IgM, IgG, IgA) in 1,003 sera samples. Current report was evaluated the IgG and IgA subclasses responsible about this protection using same methodology. IgG, IgA, and their subclasses are responsible about this circulating protection. Our study will consider the first report evaluate the levels of IgA subclasses and its relation to ages, as well as the relations between anti-Hib antibody subclass and age. The current results demonstrated that the highest levels concentrated in IgG1 and IgG2, while IgG3 and IgG4 showed the lowest levels. So, their concentrations were arranged in IgG1 > IgG2 > IgG3 > IgG4. The results indicated that the age and gender have no effect on both IgG or IgA subclasses in healthy immunized individuals enrolled. While, IgA1 concentrations were significantly higher than IgA2 in all age categories regardless of gender. It seem that the IgG1, IgG2 and IgA1 subclasses were the main constituent of Jeddah herd immunity against Hib. Finally, to the best of our knowledge, there were no previous reports that focusing on the levels of IgA subclasses and its relation to ages, so our study considers the first worldwide. [ABSTRACT FROM AUTHOR]

Background Activated phosphatidylinositol-3-OH kinase δ syndrome type 1 (APDS1) is a recently described primary immunodeficiency syndrome characterized by recurrent respiratory tract infections, lymphoid hyperplasia, and Herpesviridae infections caused by germline gain-of-function mutations of PIK3CD. Hematopoietic stem cell transplantation (HSCT) can be considered to ameliorate progressive immunodeficiency and associated malignancy, but appropriate indications, methods, and outcomes of HSCT for APDS1 remain undefined. Objective Our objective was to analyze the clinical manifestations, laboratory findings, prognosis, and treatment of APDS1 and explore appropriate indications and methods of HSCT. Methods We reviewed retrospectively the medical records of cohorts undergoing HSCT at collaborating facilities. Results Thirty-year overall survival was 86.1%, but event-free survival was 39.6%. Life-threatening events, such as severe infections or lymphoproliferation, were frequent in childhood and adolescence and were common indications for HSCT. Nine patients underwent HSCT with fludarabine-based reduced-intensity conditioning. Seven patients survived after frequent adverse complications and engraftment failure. Most symptoms improved after HSCT. Conclusion Patients with APDS1 showed variable clinical manifestations. Life-threatening progressive combined immunodeficiency and massive lymphoproliferation were common indications for HSCT. Fludarabine-based reduced-intensity conditioning–HSCT ameliorated clinical symptoms, but transplantation-related complications were frequent, including graft failure. Graphical abstract [ABSTRACT FROM AUTHOR]

Background: Immunization with killed Leishmania promastigotes without adjuvant was considered as safe, but gave variable rates of protection. Taking advantage of the immuno-modulatory effect of caffeic acid (CA), a natural polyphenolic antioxidant, we investigated its potentiating effect in autoclaved Leishmania major (ALM)-induced protection of Leishmania major-infected BALB/c.Methods: First, BALB/c mice were sensitized for 6 weeks either with CA, or ALM alone or combined with caffeic acid (ALM-CA) or Freund’s adjuvant (ALM-FA), and subsequently infected with L. major promastigotes. Second, to test the curative effect, CA was given daily for 5 weeks to susceptible mice, starting on week 4 post-infection. Sera, footpads and lymph nodes (LNs) were collected at week 9 post-infection and submitted to biochemical or histological analyses.Results: Compared to the respective controls, our results showed that CA directly healed footpad lesions and reduced the hallmarks of cutaneous leishmaniasis including oxidative inflammation, parasite load, and phagocytes influx and infestation. In sensitized mice, the protection enhanced gradually from ALM-FA, CA, ALM to ALM-CA in parallel to decreased seric IgGt levels. In contrast to ALM-FA, the combined effect of ALM and CA increased specific isotype IgG2, and decreased IL-17 and MCP-1, and phagocyte influx, as attested by the concomitant reduction in myeloperoxidase (MPO) and α-naphthyl acetate esterase (ANAE) activities. ALM-CA shifted IFN-γ/TGF-β and iNO synthase/arginase1 (iNOS/Arg1) balances in a Th1 immune response that control efficiently cutaneous lesions and LNs hypertrophy, and reactivate the death of infected phagocytes.Conclusions: Therefore, CA combined with ALM synergizes with L. major antigens for priming innate cells, through early polarization to optimal Th1 response that leads to IFN-γ and iNOS-dependent leishmanicidal activity of neutrophils and macrophages.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Human Fc receptor-like 5 (FCRL5) is a novel IgG receptor. We reported that IgG2 samples display a thousand-fold range affinity for FCRL5, indicating that attributes beyond the isotype affect binding. We hypothesized that the complex interaction could be exploited to identify distinct changes in the IgG2 molecule. We investigated using surface plasmon resonance two factors that might affect the interaction between IgG2 and FCRL5; heterogeneity related to disulfide isoforms and charge variants. We found that panitumumab and denosumab samples enriched for the more flexible A disulfide isoform bound FCRL5 with two-fold and 82-fold higher apparent affinity, respectively, than the B isoform. We next assessed whether FCRL5 binding can distinguish panitumumab charge variants which increase during storage, using two approaches. First, samples were stored at 40 °C to promote acidic variants. Heat stressed panitumumab had up to four-fold higher apparent affinity for FCRL5. Next, we used conditions that promoted deamidation, a common cause of acidic variants. We found that deamidated panitumumab had up to 14-fold higher apparent affinity for FCRL5, indicating that deamidation promotes the interaction. Statistical analyses of kinetic parameters and similarity scores obtained from sensogram comparisons indicated that IgG2 disulfide isoforms, heat stressed and deamidated samples each bind FCRL5 differently. We conclude that based on FCRL5 binding, we can discern distinct changes in the IgG2 molecule, including the disulfide isoform structure and charge variants related to deamidation. Since both IgG2 deamidation and conversion of disulfide isoforms occur in vivo , these findings elucidate the biological FCRL5 ligand. [ABSTRACT FROM AUTHOR]

Engineering of fragment crystallizable (Fc) domains of therapeutic immunoglobulin (IgG) antibodies to eliminate their immune effector functions while retaining other Fc characteristics has numerous applications, including blocking antigens on Fc gamma (Fc) receptor-expressing immune cells. We previously reported on a human IgG2 variant termed IgG2σ with barely detectable activity in antibody-dependent cellular cytotoxicity, phagocytosis, complement activity, and Fc receptor binding assays. Here, we extend that work to IgG1 and IgG4 antibodies, alternative subtypes which may offer advantages over IgG2 antibodies. In several in vitro and in vivo assays, the IgG1σ and IgG4σ variants showed equal or even lower Fc-related activities than the corresponding IgG2σ variant. In particular, IgG1σ and IgG4σ variants demonstrate complete lack of effector function as measured by antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, antibody-dependent cellular phagocytosis, and in vivo T-cell activation. The IgG1σ and IgG4σ variants showed acceptable solubility and stability, and typical human IgG1 pharmacokinetic profiles in human FcRn-transgenic mice and cynomolgus monkeys. In silico T-cell epitope analyses predict a lack of immunogenicity in humans. Finally, crystal structures and simulations of the IgG1σ and IgG4σ Fc domains can explain the lack of Fc-mediated immune functions. These variants show promise for use in those therapeutic antibodies and Fc fusions for which the Fc domain should be immunologically "silent". [ABSTRACT FROM AUTHOR]

IgG2 is the most efficient subclass for providing protection against pneumococcal pathogens. We hypothesised that some individuals may be unable to mount an effective pneumococcal capsular polysaccharide (PCP) IgG2 response despite having a normal PCP IgG concentration (PCP IgG2 deficient). The median pre-vaccination PCP IgG2 concentration was significantly lower in individuals referred for immunological investigation compared to healthy controls (2.8 mg/L range, 95% CI 1.1-88 vs. 29.5mg/L, 95% CI 13.5-90, p = 0.0002). PCP IgG:IgG2 ratios were significantly higher for the referral population than for healthy controls suggesting the increased production of PCP specific subclasses other than IgG2. The percentage of individuals with PCP IgG2 deficiency was significantly higher in referral groups compared to controls (31% vs. 5%; p = 0.0009) and in an individual with PCP IgG2 deficiency, the balance of PCP specific IgG subclass antibodies post vaccination changed from IgG2>IgG1>IgG3>IgG4 to IgG1>IgG3>IgG2>IgG4. The median PCP IgG2 concentration in those with PCP IgG2 deficiency was significantly lower in the referral groups compared to controls (7.8 mg/L, 95% CI 1.1-12 vs. 12.7 mg/L, 95% CI 11.8-13.1; p = 0.006). The data suggests a defect in the production PCP IgG2 may be present in individuals with normal PCP IgG referred for immunological investigation. [ABSTRACT FROM AUTHOR]

Bispecific antibodies (BsAbs) are designed to engage two antigens simultaneously, thus, effectively expanding the ability of antibody-based therapeutics to target multiple pathways within the same cell, engage two separate soluble antigens, bind the same antigen with distinct paratopes, or crosslink two different cell types. Many recombinant BsAb formats have emerged, however, expression and purification of such constructs can often be challenging. To this end, we have developed a chemical strategy for generating BsAbs using native IgG2 architecture. Full-length antibodies can be conjugated via disulfide bridging with linkers bearing orthogonal groups to produce BsAbs. We report that an αHER2/EGFR BsAb was successfully generated by this approach and retained the ability to bind both antigens with no significant loss of potency. [ABSTRACT FROM AUTHOR]

Detection of serum anti- Leishmania antibodies by quantitative or qualitative techniques has been the most used method to diagnose Canine Leishmaniosis (CanL). Nevertheless, saliva may represent an alternative to blood because it is easy to collect, painless and non-invasive in comparison with serum. In this study, two time-resolved immunofluorometric assays (TR-IFMAs) for quantification of anti- Leishmania IgG2 and IgA antibodies in saliva were developed and validated and their ability to distinguish Leishmania -seronegative from seropositive dogs was evaluated. The analytical study was performed by evaluation of assay precision, sensitivity and accuracy. In addition, serum from 48 dogs (21 Leishmania -seropositive and 27 Leishmania -seronegative) were analyzed by TR-IFMAs. The assays were precise, with an intra- and inter-assay coefficients of variation lower than 11%, and showed high level of accuracy, as determined by linearity under dilution (R 2 = 0.99) and recovery tests (>88.60%). Anti- Leishmania IgG2 antibodies in saliva were significantly higher in the seropositive group compared with the seronegative ( p < 0.0001), whereas no significant differences for anti- Leishmania IgA antibodies between both groups were observed. Furthermore, TR-IFMA for quantification of anti- Leishmania IgG2 antibodies in saliva showed higher differences between seropositive and seronegative dogs than the commercial assay used in serum. In conclusion, TR-IFMAs developed may be used to quantify anti- Leishmania IgG2 and IgA antibodies in canine saliva with an adequate precision, analytical sensitivity and accuracy. Quantification of anti- Leishmania IgG2 antibodies in saliva could be potentially used to evaluate the humoral response in CanL. However, IgA in saliva seemed not to have diagnostic value for this disease. For future studies, it would be desirable to evaluate the ability of the IgG2 assay to detect dogs with subclinical disease or with low antibody titers in serum and also to study the antibodies behaviour in saliva during the treatment of CanL. [ABSTRACT FROM AUTHOR]

The aims of this study were (1) to develop and validate time resolved-immunofluorometric assays for the detection of anti- Leishmania IgG2 and IgA antibodies in canine serum and (2) to evaluate the ability of these assays to quantify different amounts of anti- Leishmania antibodies in Leishmania -seronegative and seropositive dogs, determined by a commercial ELISA assay, and between different clinical stages according to LeishVet guidelines. The analytical validation showed that the assays had a good precision with intra- and inter-assay coefficients of variation lower than 10%. In addition, the assays allowed the quantification of very low concentration of antibodies as well as demonstrated a high level of accuracy, as determined by linearity under dilution (R 2 = 0.99) and recovery tests (>85%). Moreover, no cross-reactions with Ehrlichia canis, Canine Parvovirus Type 2, Anaplasma phagocytophilum , Babesia canis, Dirofilaria immitis and pyometra were found. The assays were able to detect higher values of anti- Leishmania IgG2 and IgA antibodies in seropositive dogs compared with seronegative dogs ( p < 0.0001), although an overlap between groups existed in the case of IgA. In addition, significantly higher values for both antibodies were detected in LeishVet groups II ( p < 0.05) and III ( p < 0.01) when compared with LeishVet group I. From our study, it could be concluded that the immunofluorometric assays developed would be suitable for determination of anti- Leishmania IgG2 and IgA antibodies in serum samples with an adequate precision, analytical sensitivity and accuracy. In addition, these assays showed a wider difference in the concentration of both IgG2 and IgA antibodies between seronegative and seropositive dogs and between different clinical stages of CanL than a current commercial ELISA kit. Further studies would be recommended to evaluate the diagnostic sensitivity and specificity of these new assays as well as their application in monitoring CanL. [ABSTRACT FROM AUTHOR]

Background The evaluation of the effectiveness of the vaccines (ChAdOx1-nCOV; Covishield and BBV-152; Covaxin) against coronavirus disease 2019 (COVID-19) is necessary to assess their efficacy. Because most antibodies that neutralize the coronavirus are directed against the receptor binding domain within the spike protein of the virus, these antibodies serve as markers for viral neutralizers and, in turn, for vaccine response. The present study aimed to evaluate the anti-neutralizing antibody (receptor binding domain (RBD)) and immunoglobulin G2 (IgG2) titers following the completion of the vaccination schedule (both vaccines) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methodology In this longitudinal prospective study, conducted in a tertiary care center, 30 sequentially (two doses) vaccinated study participants between the ages of 18 and 44 years were sampled for estimation of anti-RBD antibody titer and IgG2. All statistical analysis was done using SPSS version 20 (IBM Corp., Armonk, NY, USA). P-values less than 0.05 were considered significant. Results There was a statistically significant increase in the neutralizing antibody titer after one month of the second dose (z = -4.597, p < 0.001), while a significant decrease was seen in the IgG2 levels (z = -3.075, p = 0.002). The results showed a significant neutralizing effect of the vaccines being used, with Covishield being more effective than Covaxin. The levels of neutralizing antibodies were independent of all demographic variables such as age, sex, and body mass index. Conclusions This study evaluating the efficacy of the two vaccines, namely, Covishield and Covaxin, is the first of its kind in the state of Chhattisgarh. The results of this study are similar to previous studies conducted in India and outside India, concluding that Covishield is a more effective vaccine., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Nanda et al.)

In individuals who have once developed humoral immunity to an infectious/foreign antigen, the antibodies present in their body can mediate instant protection when the antigen re-enters. Such antigen-specific antibodies can be readily detected in the serum. Long term humoral immunity is, however, also critically dependent on the ability of memory B cells to engage in a secondary antibody response upon re-exposure to the antigen. Antibody molecules in the body are short lived, having a half-life of weeks, while memory B cells have a life span of decades. Therefore, the presence of serum antibodies is not always a reliable indicator of B cell memory and comprehensive monitoring of humoral immunity requires that both serum antibodies and memory B cells be assessed. The prevailing view is that resting memory B cells and B cell blasts in peripheral blood mononuclear cells (PBMC) cannot be cryopreserved without losing their antibody secreting function, and regulated high throughput immune monitoring of B cell immunity is therefore confined to—and largely limited by—the need to test freshly isolated PBMC. Using optimized protocols for freezing and thawing of PBMC, and four color ImmunoSpot® analysis for the simultaneous detection of all immunoglobulin classes/subclasses we show here that both resting memory B cells and B cell blasts retain their ability to secrete antibody after thawing, and thus demonstrate the feasibility of B cell immune monitoring using cryopreserved PBMC.

"nBackground and Aim: A major aspect of the adaptive host response in periodontitis is the antibodies. Several risk and susceptibility factors for periodontitis, including smoking, age and composition of the subgingival microflora, have also been suggested to influence antibody production. The present study was conducted to investigate plasma levels of immunoglobulin (Ig) G antibodies in periodontitis patients of Caucasian Iranian heritage referred to dental faculty, Tehran University of Medical Sciences in relation to disease severity and smoking. "nMaterials and Methods: In this study, 36 patients with severe periodontitis, 39 with moderate periodontitis and 40 controls without periodontal destruction were enrolled. From the total of 80 patients, 21 were diagnosed with aggressive periodontitis and 54 with chronic periodontitis. IgG isotypes were analyzed in plasma samples. "nResults: Patients group in comparison with control group had shown higher level of Immuno globolins. There was no significant difference about the IgG1 level in moderate and seven group and also in chronic and aggressive groups (p