Immunoglobulin G and immunoglobulin G subclass concentrations differ according to sex and race

Evaluation of the precision of the Plasmodium knowlesi growth inhibition assay for Plasmodium vivax Duffy-binding protein-based malaria vaccine development

Recent data indicate increasing disease burden and importance of Plasmodium vivax (Pv) malaria. A robust assay will be essential for blood-stage Pv vaccine development. Results of the in vitro growth inhibition assay (GIA) with transgenic P. knowlesi (Pk) parasites expressing the Pv Duffy-binding protein region II (PvDBPII) correlate with in vivo protection in the first PvDBPII controlled human malaria infection (CHMI) trials, making the PkGIA an ideal selection tool once the precision of the assay is defined. To determine the precision in percentage of inhibition in GIA (%GIA) and in GIA50 (antibody concentration that gave 50 %GIA), ten GIAs with transgenic Pk parasites were conducted with four different anti-PvDBPII human monoclonal antibodies (mAbs) at concentrations of 0.016 to 2 mg/mL, and three GIAs with eighty anti-PvDBPII human polyclonal antibodies (pAbs) at 10 mg/mL. A significant assay-to-assay variation was observed, and the analysis revealed a standard deviation (SD) of 13.1 in the mAb and 5.94 in the pAb dataset for %GIA, with a LogGIA50 SD of 0.299 (for mAbs). Moreover, the ninety-five percent confidence interval (95 %CI) for %GIA or GIA50 in repeat assays was calculated in this investigation. The error range determined in this study will help researchers to compare PkGIA results from different assays and studies appropriately, thus supporting the development of future blood-stage malaria vaccine candidates, specifically second-generation PvDBPII-based formulations.

IgG subclass levels in referred hemochromatosis probands with HFE p.C282Y/p.C282Y

BACKGROUND

IgG subclass levels in hemochromatosis are incompletely characterized.

METHODS

We characterized IgG subclass levels of referred hemochromatosis probands with HFE p.C282Y/p.C282Y (rs1800562) and human leukocyte antigen (HLA)-A and -B typing/haplotyping and compared them with IgG subclass levels of eight published cohorts of adults unselected for hemochromatosis.

RESULTS

There were 157 probands (82 men, 75 women; mean age 49±13 y). Median serum ferritin, mean body mass index (BMI), median IgG4, and median phlebotomy units to achieve iron depletion were significantly higher in men. Diabetes, cirrhosis, and HLA-A*03,-B*44, -A*03,B*07, and -A*01,B*08 prevalences and median absolute lymphocyte counts in men and women did not differ significantly. Mean IgG subclass levels [95% confidence interval] were: IgG1 5.31 g/L [3.04, 9.89]; IgG2 3.56 g/L [1.29, 5.75]; IgG3 0.61 g/L [0.17, 1.40]; and IgG4 0.26 g/L [<0.01, 1.25]. Relative IgG subclasses were 54.5%, 36.6%, 6.3%, and 2.7%, respectively. Median IgG4 was higher in men than women (0.34 g/L [0.01, 1.33] vs. 0.19 g/L [<0.01, 0.75], respectively; p = 0.0006). A correlation matrix with Bonferroni correction revealed the following positive correlations: IgG1 vs. IgG3 (p<0.01); IgG2 vs. IgG3 (p<0.05); and IgG2 vs. IgG4 (p<0.05). There was also a positive correlation of IgG4 vs. male sex (p<0.01). Mean IgG1 was lower and mean IgG2 was higher in probands than seven of eight published adult cohorts unselected for hemochromatosis diagnoses.

CONCLUSIONS

Mean IgG subclass levels of hemochromatosis probands were 5.31, 3.56, 0.61, and 0.26 g/L, respectively. Median IgG4 was higher in men than women. There were positive associations of IgG subclass levels. Mean IgG1 may be lower and mean IgG2 may be higher in hemochromatosis probands than adults unselected for hemochromatosis.

A retrospective multicenter study on clinical and serological parameters in patients with MuSK myasthenia gravis with and without general immunosuppression

Introduction

Muscle-specific kinase (MuSK)- myasthenia gravis (MG) is caused by pathogenic autoantibodies against MuSK that correlate with disease severity and are predominantly of the IgG4 subclass. The first-line treatment for MuSK-MG is general immunosuppression with corticosteroids, but the effect of treatment on IgG4 and MuSK IgG4 levels has not been studied.

Methods

We analyzed the clinical data and sera from 52 MuSK-MG patients (45 female, 7 male, median age 49 (range 17-79) years) from Italy, the Netherlands, Greece and Belgium, and 43 AChR-MG patients (22 female, 21 male, median age 63 (range 2-82) years) from Italy, receiving different types of immunosuppression, and sera from 46 age- and sex-matched non-disease controls (with no diagnosed diseases, 38 female, 8 male, median age 51.5 (range 20-68) years) from the Netherlands. We analyzed the disease severity (assessed by MGFA or QMG score), and measured concentrations of MuSK IgG4, MuSK IgG, total IgG4 and total IgG in the sera by ELISA, RIA and nephelometry.

Results

We observed that MuSK-MG patients showed a robust clinical improvement and reduction of MuSK IgG after therapy, and that MuSK IgG4 concentrations, but not total IgG4 concentrations, correlated with clinical severity. MuSK IgG and MuSK IgG4 concentrations were reduced after immunosuppression in 4/5 individuals with before-after data, but data from non-linked patient samples showed no difference. Total serum IgG4 levels were within the normal range, with IgG4 levels above threshold (1.35g/L) in 1/52 MuSK-MG, 2/43 AChR-MG patients and 1/45 non-disease controls. MuSK-MG patients improved within the first four years after disease onset, but no further clinical improvement or reduction of MuSK IgG4 were observed four years later, and only 14/52 (26.92%) patients in total, of which 13 (93.3%) received general immunosuppression, reached clinical remission.

Discussion

We conclude that MuSK-MG patients improve clinically with general immunosuppression but may require further treatment to reach remission. Longitudinal testing of individual patients may be clinically more useful than single measurements of MuSK IgG4. No significant differences in the serum IgG4 concentrations and IgG4/IgG ratio between AChR- and MuSK-MG patients were found during follow-up. Further studies with larger patient and control cohorts are necessary to validate the findings.

A randomized first-in-human phase I trial of differentially adjuvanted Pfs48/45 malaria vaccines in Burkinabé adults

BACKGROUNDMalaria transmission-blocking vaccines aim to interrupt the transmission of malaria from one person to another.METHODSThe candidates R0.6C and ProC6C share the 6C domain of the Plasmodium falciparum sexual-stage antigen Pfs48/45. R0.6C utilizes the glutamate-rich protein (GLURP) as a carrier, and ProC6C includes a second domain (Pfs230-Pro) and a short 36-amino acid circumsporozoite protein (CSP) sequence. Healthy adults (n = 125) from a malaria-endemic area of Burkina Faso were immunized with 3 intramuscular injections, 4 weeks apart, of 30 μg or 100 μg R0.6C or ProC6C each adsorbed to Alhydrogel (AlOH) adjuvant alone or in combination with Matrix-M (15 μg or 50 μg, respectively). The allocation was random and double-blind for this phase I trial.RESULTSThe vaccines were safe and well tolerated with no vaccine-related serious adverse events. A total of 7 adverse events, mild to moderate in intensity and considered possibly related to the study vaccines, were recorded. Vaccine-specific antibodies were highest in volunteers immunized with 100 μg ProC6C-AlOH with Matrix-M, and 13 of 20 (65%) individuals in the group showed greater than 80% transmission-reducing activity (TRA) when evaluated in the standard membrane feeding assay at 15 mg/mL IgG. In contrast, R0.6C induced sporadic TRA.CONCLUSIONAll formulations were safe and well tolerated in a malaria-endemic area of Africa in healthy adults. The ProC6C-AlOH/Matrix-M vaccine elicited the highest levels of functional antibodies, meriting further investigation.TRIAL REGISTRATIONPan-African Clinical Trials Registry (https://pactr.samrc.ac.za) PACTR202201848463189.FUNDINGThe study was funded by the European and Developing Countries Clinical Trials Partnership (grant RIA2018SV-2311).

Clinical Performance of Immunonephelometric Assay and Chemiluminescent Immunoassay for Detection of IgG Subclasses in Chinese

BACKGROUND

Detection of IgG subclasses (IgGSc) is vital for the diagnosis and management of disease, especially IgG4-related diseases (IgG4-RD). This study aimed to evaluate the performances of the chemiluminescent immunoassay (CLIA) for detecting IgGSc and diagnosing IgG4-RD by IgGSc.

METHODS

A total of 40 individuals with IgG4-RD, 40 with primary Sjogren's syndrome (pSS), and 40 healthy controls (HCs) were enrolled. Serum samples were collected for the simultaneous detection of IgG1, IgG2, IgG3, and IgG4 by the Siemens immunonephelometric assay and the CLIA. The correlation analysis was performed, and diagnostic value was analyzed by the receiver operating characteristic (ROC) curve.

RESULTS

Patients with IgG4-RD had higher IgG4 (p < 0.001) and lower IgG1 (p < 0.001) than those with pSS, and HC. The results by the Siemens immunonephelometric assay and the CLIA showed a strong correlation in detecting IgG1, IgG2, IgG3, and IgG4 (r = 0.937, r = 0.847, r = 0.871, r = 0.990, all p < 0.001, respectively). The sum of IgG1, IgG2, IgG3, and IgG4 using two assays strongly correlated with total IgG by the IMMAGE 800 (r = 0.866, r = 0.811, both p < 0.001, respectively). For discriminating IgG4-RD from pSS and HC, no significant differences were observed in CLIA IgG4 and Siemens immunonephelometric assay IgG4 (z = 0.138, p = 0.891), which provided the area under the curves (AUCs) of 0.951 (p < 0.001) and 0.950 (p < 0.001), respectively. The AUCs of CLIA IgG1 and Siemens immunonephelometric assay IgG1 in distinguishing pSS from IgG4-RD and HC were 0.761 (p < 0.001) and 0.765 (p < 0.001), respectively, with no significant differences (z = 0.228, p = 0.820).

CONCLUSIONS

The CLIA and the Siemens immunonephelometric assay appeared to have good consistency with comparable diagnostic value in detecting IgGSc, especially IgG4, and IgG1 that can accurately identify IgG4-RD or pSS in clinical practice.

Impact of steroids on the immune profiles of children with asthma living in the inner-city

Background: Inner-city asthma is associated with high morbidity and systemic steroid use. Chronic steroid use impacts immune function; however, there is a lack of data with regard to the extent of immunosuppression in patients with asthma and who are receiving frequent systemic steroids. Objective: To identify the impact of frequent systemic steroid bursts on the immune function of children with asthma who live in the inner city. Methods: Children ages 3-18 years with asthma were divided into study (≥2 systemic steroid bursts/year) and control groups (0-1 systemic steroid bursts/year). Lymphocyte subsets; mitogen proliferation assay; total immunoglobulin G (IgG) value, and pneumococcal and diphtheria/tetanus IgG values were evaluated. Results: Ninety-one participants were enrolled (study group [n = 42] and control group [n = 49]). There was no difference in adequate pneumococcal IgG value, diphtheria/tetanus IgG value, mitogen proliferation assays, lymphocyte subsets, and IgG values between the two groups. Children who received ≥2 steroid bursts/year had a significantly lower median pneumococcal IgG serotype 7F value. Most of the immune laboratory results were normal except for the pneumococcal IgG value. Most of the participants (n/N = 72/91 [79%]) had an inadequate pneumococcal IgG level (<7/14 serotypes ≥1.3 µg/mL). The participants with inadequate pneumococcal IgG level and who received a pneumococcal polysaccharide vaccine 23 (PPSV23) boost had a robust response. There was no significant difference in infection, steroid exposure, asthma severity, or morbidities between those with adequate versus inadequate pneumococcal IgG values. Conclusion: Children with asthma who live in the inner city and receive ≥2 steroid bursts/year do not have a significantly different immune profile from those who receive ≤1 steroid bursts/year do not have a significantly different immune profile from those who do not. Although appropriately vaccinated, most participants had an inadequate pneumococcal IgG level, regardless of steroid exposure and asthma severity. These children may benefit from PPSV23.

Mass spectrometry in IgG4-related disease diagnosis

We compared liquid chromatography tandem mass spectrometry (LC-MS/MS) against Binding Site immunonephelometry (BSIN) with regards to these methods' abilities to diagnose IgG4-related disease (IgG4-RD). IgG subclasses were gathered from laboratory from December 2011 to December 2020. The IgG4-RD positive and negative patients were diagnosed according to the ACR/EULAR classification criteria by extensive chart review. Both methods' results were compared in terms of test characteristics. For BSIN, there were 43 IgG4-RD positive cases and 174 disease negative cases, while for LC-MS/MS, there were 102 IgG4-RD positive cases and 562 disease negative cases. The majority of IgG4-RD patients by BSIN and LC-MS/MS had an elevated IgG4 level, 81% and 86%, respectively. For BSIN, the ROC curve, cut-off value of 1.25 g/L, had a sensitivity of 81% and a specificity of 84%. For LC-MS/MS, the ROC curve, cut-off value of 1.25 g/L, had a sensitivity of 86% and a specificity of 84%. The responder index score to IgG4 level r-correlation value for BSIN and LC-MS/MS was 0.5 and 0.6, respectively. In our center, LC-MS/MS and BSIN are equivalent test methods in IgG4-RD diagnosis. IgG4 level does correlate with disease activity by the responder index. LC-MS/MS is a valid and equally reliable alternative to BSIN in the diagnosis of IgG4-related disease.

Shared and unique antibody and B cell profiles in HIV-positive and HIV-negative individuals with cryptococcal meningoencephalitis

Host non-T cell markers to aid in the diagnosis of cryptococcal meningoencephalitis (CM) have not been identified. In this case-control study, we characterized antibody and B cell profiles in HIV-negative and HIV-positive Vietnamese individuals of the Kinh ethnicity recently diagnosed with CM and controls. The study included 60 HIV-negative with no known immunocompromising condition and 60 HIV-positive individuals, with 30 CM cases and 30 controls in each group. Participants were matched by age, sex, HIV serostatus, and CD4 count in the HIV-positive group. Plasma immunoglobulin (Ig) levels, including IgG1, IgG2, IgM, and IgA, Cryptococcus spp. glucuronoxylomannan (GXM)- and laminarin (branched ${\rm{\beta }}$-[1-3]-glucan)-binding IgG, IgM, IgA levels, and peripheral blood B cell subsets were measured. Logistic regression, principal component, and mediation analyses were conducted to assess associations between antibody, B cell levels, and CM. The results showed that GXM-IgG levels were higher and IgG1 and IgG2 were lower in CM cases than controls, regardless of HIV status. In HIV-negative individuals, IgG2 mediated an inverse association between CD19+CD27+CD43+CD5- (B-1b-like) cells and CM. In HIV-positive individuals, lower levels of IgA, laminarin-IgA, and CD19+CD27+IgM+IgD- (IgM+ memory B) cells were each associated with CM. The shared and distinct antibody and B cell profiles identified in HIV-negative and HIV-positive CM cases may inform the identification of non-T-cell markers of CM risk or unsuspected disease, particularly in HIV-negative individuals.

Current Issues in the Management of IgG Subclass Deficiencies in Adults With Chronic Respiratory Diseases

Primary immunodeficiency diseases (PIDs) are uncommon in adults; however, immunoglobulin G subclass deficiency (IGGSCD) is often found in a subset of adult patients with chronic respiratory diseases. As quantitative laboratory tests are used to diagnose IGGSCD, the clinical significance of IGGSCD remains controversial. However, respiratory infection is a common presenting feature of IGGSCD, and respiratory complications are responsible for subsequent morbidities, such as severe asthma, bronchiectasis, chronic obstructive airway diseases, and mortality. This review summarizes the current epidemiological data for PIDs, focusing on IGGSCD in the adult population. In addition, the investigation, treatment, and management strategies are detailed, including distinct issues faced by patients with chronic airway disease and their physicians in the proper diagnosis and treatment of IGGSCD.

The Potential Diagnostic Biomarkers for the IgG Subclass in Coal Workers' Pneumoconiosis

Evidence suggests that exposure to coal dust increases immunoglobulin concentration. However, there is a paucity of data reporting immunoglobulin G (IgG) subclass in coal workers' pneumoconiosis (CWP). Therefore, this study intended to evaluate potential diagnostic biomarkers for the disease. CWP patients, dust-exposed workers without pneumoconiosis (DEW), and matched healthy controls (HCs) presented to the General Hospital of Datong Coal Mining Group and Occupational Disease Prevention and Treatment Hospital of Datong Coal Mining Group between May 2019 and September 2019 were recruited. The serum immunoglobulin concentration was determined by the multiplex immunoassay technique. Totally, 104 CWP patients, 109 DEWs, and 74 HCs were enrolled. Serum levels of IgG1, IgG2, IgM, and IgA were elevated in CWPs compared with those in DEWs and HCs (P < 0.05). The order of diagnostic accuracy between CWPs and DEWs depicted by the receiver operating characteristic (ROC) curve was IgG2, IgM, IgG1, IgG3, and IgA. Significantly higher IgG1/IgG3 and IgG2/IgG3 ratios were observed in the CWP group than in DEW and HC groups. Based on the IgG2/IgG3 ratio, the area under the ROC curve between CWP and DEW was 0.785 (95% CI 0.723-0.838), with a sensitivity of 73.1% and a specificity of 73.4%. Our findings suggest that IgG1, IgG2, IgM, and IgA are higher in the CWPs than DEWs and HCs. The IgG2/IgG3 ratio provides a viable alternative for the diagnosis of CWP.

Enrichment of serum IgG4 in MuSK myasthenia gravis patients

Muscle-specific kinase (MuSK) myasthenia gravis (MG) is a neuromuscular autoimmune disease belonging to a growing group of IgG4 autoimmune diseases (IgG4-AIDs), in which the majority of pathogenic autoantibodies are of the IgG4 subclass. The more prevalent form of MG with acetylcholine receptor (AChR) antibodies is caused by IgG1-3 autoantibodies. A dominant role for IgG4 in autoimmune disease is intriguing due to its anti-inflammatory characteristics. It is unclear why MuSK autoantibodies are predominantly IgG4. We hypothesized that MuSK MG patients have a general predisposition to generate IgG4 responses, therefore resulting in high levels of circulating IgG4. To investigate this, we quantified serum Ig isotypes and IgG subclasses using nephelometric and turbidimetric assays in MuSK MG and AChR MG patients not under influence of immunosuppressive treatment. Absolute serum IgG1 was increased in both MuSK and AChR MG patients compared to healthy donors. In addition, only MuSK MG patients on average had significantly increased and enriched serum IgG4. Although more MuSK MG patients had elevated serum IgG4, for most the IgG4 serum levels fell within the normal range. Correlation analyses suggest MuSK-specific antibodies do not solely explain the variation in IgG4 levels. In conclusion, although serum IgG4 levels are slightly increased, the levels do not support ubiquitous IgG4 responses in MuSK MG patients as the underlying cause of dominant IgG4 MuSK antibodies.

Diagnosis of inflammatory bowel disease according to human IgG4 and possibilities of evaluating efficacy of the therapy

Taking into account the progress of understanding diagnosis, course prognosis, evaluation of effectiveness of therapy of inflammatory bowel disease and also differentiation diagnosis between its main forms – ulcerative colitis and Crohn’s disease, the search for efficient non-invasive markers for solving those issues is extremely relevant. The patients were divided into groups depending on nosology and severity of the course of the disease. All the patients had undergone endoscopic study for diagnosis verification and biopsy samples were taken for further detection of tissue IgG4 using the immunohistochemical method. Also, we determined concentration of serum IgG4. Increase in IgG4content in blood serum was determined in 54.0% of the cases of inflammatory bowel disease. Concentration of IgG4 in patients suffering ulcerative colitis was higher (by 2.31 and 2.46 times) compared with its level in the control group and patients with Crohn’s disease, respectively. We found relationships between the concentration of serum IgG4 and the activity of the disease. In patients with ulcerative colitis, increased tissue IgG4 was found more often than in patients with Crohn’s disease (by 2.77 times, Р < 0.05). We determined the relationship between tissue IgG4 and histological activity. Simultaneous increase in serum IgG4 and presence of tissue IgG4 during ulcerative colitis were more frequent than during Crohn’s disease (by 2.66 times). In all examined groups of patients, we determined decrease in serum IgG4 content (by 1.66 times) after treatment. Concentration of serum IgG4 and positive tissue IgG4 in ulcerative colitis patients exceeded such in Crohn’s disease patients, which may be used for differentiation diagnosis between those disease types. We determined dependence of IgG4 concentration on severity and duration of the disease, which could be used as a prognostic marker. Decrease in IgG4 content in blood serum against the background of the therapy shows that this indicator could be used as a marker of treatment efficacy. Perspectives of further studies are as follows: parameters of concentration of serum IgG4 and presence of tissue IgG4 could be used as diagnostic and prognostic biomarkers and be introduced to practice for differentiation diagnosis between ulcerative colitis and Crohn’s disease, and could be used as prognostic marker of severity of the disease and therapy efficacy.

"Common variable immunodeficiency: Challenges for diagnosis"

Common variable immunodeficiency is a heterogeneous condition characterized by B cell dysfunction with reduced serum immunoglobulin levels and a highly variable spectrum of clinical manifestations ranging from recurrent infections to autoimmune disease. The diagnosis of CVID is often challenging due to the diverse clinical presentation of patients and the existence of multiple diagnostic criteria without a universally adopted consensus. Laboratory evaluation to assist with diagnosis currently includes serum immunoglobulin testing, immunophenotyping, assessment of vaccine response, and genetic testing. Additional emerging techniques include investigation of the B cell repertoire and the use of machine learning algorithms. Advances in our understanding of common variable immunodeficiency will ultimately contribute to earlier diagnosis and novel interventions with the goal of improving prognosis for these patients.

Differential proteomics between unhatched male and female egg yolks reveal the molecular mechanisms of sex-allocation and sex-determination in chicken

There is a huge demand to identify the sex of unhatched fertilized eggs for laying industry and to understand the differences between male and female eggs as early as possible. Then the molecular mechanisms of sex determination and sex allocation in chicken were revealed. Therefore, TMT proteomic was applied to characterize the variation of molecular matrix between unhatched male and female egg yolks. A total of 411 proteins were identified and 35 differentially expressed proteins (DEPs), including 375332005, 015809562, 763550308 (upregulated, UPs) and 1337178851, 89000557, 89000581 (downregulated, DPs), etc. were confirmed between them. Gene ontology analyses showed that DEPs were mainly involved in response to stimulus, distributed in the extracellular region and participated in binding; KEGG analyses showed that few DPs were participated in cell growth and death, transport and catabolism, signaling molecules, interaction and were enriched in ubiquitin mediated proteolysis, endocytosis, ferroptosis, etc. metabolic pathways. Moreover, most of the DEPs and related metabolic pathways were associated with sex hormones. More importantly, this study supports maternal sex-allocation theory and extends our understanding of the molecular mechanism of sex determination and differentiation in avian. Which also provides a powerful evidence for ovo sexing of unhatched fertilized domestic chicken eggs by nondestructive approach and will be of great significance to eggs processing and production.

Active IgG4-related disease with bone marrow involvement: a report of 2 cases and case-based review

IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory disease, histopathologically characterized by dense lymphoplasmacytic infiltration rich in IgG4-positive plasma cells in affected organs. Classic hematologic presentations including lymphadenopathy, eosinophilia and polyclonal hypergammaglobulinemia are common, whereas bone marrow involvement of IgG4-RD is rarely reported. Here we present two patients of multi-organ IgG4-RD with bone marrow involvement, one on bone marrow biopsy, and the other on PET/CT. Presentations of other organ involvement included biopsy-proven IgG4-related tubulointerstitial nephritis, lymphadenopathies, submaxillary glands, arteritis, asthma, dysosmia, and constitutional symptoms. Bone marrow involvement was initially suspected due to leukopenia, anemia and thrombocytopenia in case#1, and was finally confirmed by histological evidence of significant IgG4-positive plasma cells infiltration in bone marrow. In case#2, we incidentally observed high uptakes of multi-bone marrow on ¹⁸F-FDG-PET/CT, with the maximum SUV value similar to that of the kidneys, submaxillary glands and hilar, mediastinal lymph nodes by ¹⁸F-FDG-PET/CT. Symptoms and all the hematologic presentation improved rapidly in both patients after steroids initiation. These two cases illustrate the rare bone marrow involvement in active IgG4-RD accompanied by other hematologic syndromes. The significance of disease pathogenesis is worthy of further study.

Anti-Neuronal IgG4 Autoimmune Diseases and IgG4-Related Diseases May Not Be Part of the Same Spectrum: A Comparative Study

Background

IgG4 is associated with two emerging groups of rare diseases: 1) IgG4 autoimmune diseases (IgG4-AID) and 2) IgG4-related diseases (IgG4-RLD). Anti-neuronal IgG4-AID include MuSK myasthenia gravis, LGI1- and Caspr2-encephalitis and autoimmune nodo-/paranodopathies (CNTN1/Caspr1 or NF155 antibodies). IgG4-RLD is a multiorgan disease hallmarked by tissue-destructive fibrotic lesions with lymphocyte and IgG4 plasma cell infiltrates and increased serum IgG4 concentrations. It is unclear whether IgG4-AID and IgG4-RLD share relevant clinical and immunopathological features.

Methods

We collected and analyzed clinical, serological, and histopathological data in 50 patients with anti-neuronal IgG4-AID and 19 patients with IgG4-RLD.

Results

A significantly higher proportion of IgG4-RLD patients had serum IgG4 elevation when compared to IgG4-AID patients (52.63% vs. 16%, p = .004). Moreover, those IgG4-AID patients with elevated IgG4 did not meet the diagnostic criteria of IgG4-RLD, and their autoantibody titers did not correlate with their serum IgG4 concentrations. In addition, patients with IgG4-RLD were negative for anti-neuronal/neuromuscular autoantibodies and among these patients, men showed a significantly higher propensity for IgG4 elevation, when compared to women (p = .005). Last, a kidney biopsy from a patient with autoimmune paranodopathy due to CNTN1/Caspr1-complex IgG4 autoantibodies and concomitant nephrotic syndrome did not show fibrosis or IgG4+ plasma cells, which are diagnostic hallmarks of IgG4-RLD.

Conclusion

Our observations suggest that anti-neuronal IgG4-AID and IgG4-RLD are most likely distinct disease entities.

The association of smoking with immunoglobulin G4-related disease: a case-control study

OBJECTIVE

To evaluate the association between cigarette smoking and the odds of IgG4-related disease (IgG4-RD).

METHODS

We performed a case-control study of patients with IgG4-RD compared in a 1:5 ratio with age-, race- and sex-matched controls. We included cases evaluated at the Massachusetts General Hospital, a hospital within the Mass General Brigham (MGB) System. Controls were identified from the MGB Biobank. Smoking status at the date of IgG4-RD diagnosis or corresponding index date was determined. Conditional logistic regression was used to estimate the association between cigarette smoking and the odds of having IgG4-RD.

RESULTS

There were 234 IgG4-RD cases and 1170 controls. The mean age (59 years), sex (62% male) and race (75% white) were well balanced. IgG4-RD cases were more likely to be current smokers compared with controls [25 (11%) vs 70 (6%); odds ratio (OR) 1.79 (95% CI 1.08, 2.95)]. This association was strongest among female cases [13 (14%) vs 19 (4%);, OR 3.79 (95% CI 1.71, 8.39)] and those with retroperitoneal fibrosis [RPF; 13 (28%) vs 13 (6%);, OR 6.93 (95% CI 2.78, 17.26)] or normal IgG4 concentrations [21 (21%) vs 21 (4%); OR 6.22 (95% CI 3.09, 12.49)]. When RPF cases were excluded, there was no longer an association between current smoking and the odds of having IgG4-RD [12 (6%) vs 57 (6%); OR 0.95 (95% CI 0.49, 1.86)].

CONCLUSION

Being a current smoker is associated with greater odds of having IgG4-RD, especially among women and those with RPF or normal IgG4 concentrations. Current smoking is the first recognized modifiable risk factor for IgG4-RD.

Characterization of an Anti-Ebola virus Hyperimmune Globulin Derived from Convalescent Plasma

BACKRGOUND

Convalescent plasma has been used to treat many viral diseases including Ebola. The manufacture of a purified anti-Ebola virus (EBOV) intravenous immunoglobulin (IVIG) from pooled convalescent plasma is described in this paper.

METHODS

An ELISA targeting an EBOV surface glycoprotein antigen was used to determine the immunoglobulin titer of pooled plasma and purified anti-EBOV IVIG. Anti-EBOV IVIG was also tested in neutralization assays using a vesicular stomatitis virus pseudovirion expressing EBOV glycoprotein on its surface and with live EBOV. Finally, the efficacy of the anti-EBOV IVIG was assessed in a mouse model of EBOV infection.

RESULTS

In the ELISA, the anti-EBOV IVIG was shown to have a seven-fold increase in IgG titer over pooled convalescent plasma. In both the pseudovirion and live virus assays, the anti-EBOV IVIG showed approximately five- to six-fold increased potency over pooled plasma. Anti-EBOV IVIG also significantly improved survivability in mice infected with the virus when administered concurrently or two days after infection.

CONCLUSIONS

These data support this purified anti-EBOV IVIG merits additional investigation and clinical trials for treatment and post-exposure prophylaxis of Ebola virus disease. The experience gained can be applied to manufacture hyperimmune globulins against other emerging viruses.

Hidden IgG4-Related Coronary Disease

OBJECTIVES

We present a full autopsy with a focused radiology and pathologic review of the coronary arteries. We hope that the results described in this article will help create better diagnostic measures and prevent future coronary artery vasculitis misdiagnosis.

METHODS

A full autopsy was performed on the body of Dr Myung Choong Yoon, with full consent from the family, within the department of pathology and laboratory medicine at Vancouver General Hospital. Tissue samples from the heart, brain, lungs, and spinal cord were submitted to specialist pathologists for histologic processing.

RESULTS

Cardiac gated computed tomography coronary angiography suggested periarteritis. Coexistent calcified coronary atherosclerosis with linear calcifications was present along the luminal wall, along with coronary artery ectasia. Histologic assessment confirmed features of dense adventitial fibrosis around the coronary arteries, with an exuberant lymphoplasmacytic infiltrate and numerous plasma cells consistent with IgG4-related disease. The media of the coronary arteries was markedly attenuated or completely absent, which likely contributed to the coronary arterial ectasia noted microscopically. These findings confirmed IgG4-related coronary arteritis.

CONCLUSIONS

Coronary periarteritis is an uncommon manifestation of IgG4-related disease established radiographically and later by autopsy.

Malignancy Risk of Immunoglobin G4-Related Disease: Evidence from a Large Cohort Multicenter Retrospective Study

Introduction

The aim of this work was to evaluate the prevalence of malignancies in a multicenter cohort of Chinese patients with immunoglobulin G4-related disease (IgG4-RD) and to identify the related risk factors of malignancy in IgG4-RD patients.

Methods

We retrospectively analyzed 602 IgG4-RD patients who were recruited in five medical centers from 2009 to 2020. Standardized prevalence ratios (SPRs) against the general Chinese population were calculated along with 95% confidence intervals (CIs). We identified the risk factors of malignancy in IgG4-RD and calculated the odds ratios (ORs) of different factors. We then developed and validated a prediction model for malignancy risk of IgG4-RD based on our cohort.

Results

We observed a significantly increased prevalence of total malignancies in this cohort compared to the general Chinese population (SPR 8.66 [95% CI 5.84, 12.31]). Logistic regression analysis indicated that eosinophil percentage (OR 1.096 [95% CI 1.019–1.179], P = 0.016), serum albumin-to-globulin ratio (AGR) (OR 0.185 [95% CI 0.061–0.567], P = 0.002) and autoimmune pancreatitis (OR 2.400 [95% CI 1.038–5.549], P = 0.041) were three potential risk factors of malignancy in IgG4-RD patients. Four predictors were included in our final prediction model: age at IgG4-RD diagnosis, eosinophil percentage, AGR and autoimmune pancreatitis. The nomogram performed well in the internal validation cohort, with a concordance index (C-index) of 0.738.

Conclusions

A significantly increased prevalence of total malignancies was observed in our multicenter cohort. Eosinophil percentage and autoimmune pancreatitis are risk factors, whereas AGR is negatively associated with malignancy in IgG4-RD. A prediction model for malignancy risk of IgG4-RD was first developed and validated in our study.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-021-00326-8.

Clinical utility of serum IgG4 measurement

This article will review the structure and function of IgG4, methods of measuring serum IgG4 concentrations, clinical conditions associated with increased and decreased serum IgG4, and the test characteristics of serum IgG4 in the diagnosis and management of Immunoglobulin G4-Related Disease (IgG4-RD). The four subclasses of IgG were discovered in 1964 through experiments on monoclonal IgG in patients with myeloma. Since 2001, interest in measuring serum IgG subclasses has increased dramatically due to the emergence of IgG4-RD, a multisystem fibroinflammatory condition wherein polyclonal serum IgG4 concentration is increased in approximately 70% of cases. Increased serum IgG4 typically manifests as a restriction in the anodal gamma region on serum protein electrophoresis, often with beta-gamma bridging, and can be mistaken as a monoclonal protein or polyclonal increase in IgA. Limitations of current clinical methods used in quantitation of serum IgG4 concentrations will be discussed, including the common immunonephelometric assays and LC-MS/MS based assays. Polyclonal IgG4 elevation is not specific for IgG4-RD, and may also occur in conditions such as eosinophilic granulomatosis with polyangiitis (EGPA), lymphoma, and multicentric Castleman disease (MCD). Race and gender differences also affect interpretation of serum IgG4 concentrations, for instance Asians have a higher serum IgG4 concentration than Whites and males have a higher concentration than females.