IgG anti-IgE Research Articles

Prevalence and Clinical Relevance of Anti-FcεRI Autoantibody in Crohn's Disease.

Mast cells can be activated in various ways and were shown to be involved in the development of Crohn's disease (CD). The diagnosis of CD is still challenging, and seeking novel biomarkers is a worthwhile endeavor. An indirect enzyme-linked immunosorbent assay (ELISA) was successfully established for semi-quantitative detection of IgG anti-FcεRI in serum using human FcεRIα coated microplates and an enzyme-labeled anti-human IgG as secondary antibodies. The optimal working conditions were explored, followed by conducting the method evaluation. The serum samples and clinical data of 117 CD patients and 75 healthy controls were collected. IgE was measured by the rate turbidity turbidimetry; IgG anti-IgE and IgG anti-FcεRI were detected by ELISA. IgG anti-pancreatic antibody (PAB) and anti-Saccharomyces cerevisiae antibody (ASCA) were determined by indirect immunofluorescence assay. Data were analyzed concerning the clinical characteristics. IgG anti-FcεRI was an effective marker for CD (P < 0.001), but IgE and IgG anti-IgE (P = 0.089, 0.219, respectively) were not. There was a positive correlation between anti-IgE and anti-FcεRI (R = 0.380, P < 0.001). Anti-FcεRI positive patients behaved with higher disease activity [OR: 1.478 (1.200~1.821), P < 0.001], but were less likely to be located in L4 among Montreal classification [OR: 0.253 (0.077~0.837), P = 0.024]. Existing indicators, PAB and ASCA, behaved with high specificity (both > 95%) with low sensitivity (both < 30%). The combination of anti-FcεRI with existing markers significantly improved the diagnostic efficiency [AUC: 0.879 (0.831~0.928)]. An ELISA for the detection of anti-FcεRI was established and validated, which may contribute to facilitating research on Crohn's diseases. Anti-FcεRI positive CD patients were associated with higher disease activity indices, suggesting its potential value in the diagnosis and management of CD.

Autoantibodies to IgE can induce the release of proinflammatory and vasoactive mediators from human cardiac mast cells

Mast cells are multifunctional immune cells with complex roles in tissue homeostasis and disease. Cardiac mast cells (HCMCs) are strategically located within the human myocardium, in atherosclerotic plaques, in proximity to nerves, and in the aortic valve. HCMCs express the high-affinity receptor (FcεRI) for IgE and can be activated by anti-IgE and anti-FcεRI. Autoantibodies to IgE and/or FcεRI have been found in the serum of patients with a variety of immune disorders. We have compared the effects of different preparations of IgG anti-IgE obtained from patients with atopic dermatitis (AD) with rabbit IgG anti-IgE on the release of preformed (histamine and tryptase) and lipid mediators [prostaglandin D2 (PGD2) and cysteinyl leukotriene C4 (LTC4)] from HCMCs. Functional human IgG anti-IgE from one out of six AD donors and rabbit IgG anti-IgE induced the release of preformed (histamine, tryptase) and de novo synthesized mediators (PGD2 and LTC4) from HCMCs. Human IgG anti-IgE was more potent than rabbit IgG anti-IgE in inducing proinflammatory mediators from HCMCs. Human monoclonal IgE was a competitive antagonist of both human and rabbit IgG anti-IgE. Although functional anti-IgE autoantibodies rarely occur in patients with AD, when present, they can powerfully activate the release of proinflammatory and vasoactive mediators from HCMCs.

IgG Autoantibodies Against IgE from Atopic Dermatitis Can Induce the Release of Cytokines and Proinflammatory Mediators from Basophils and Mast Cells.

IgE-mediated release of proinflammatory mediators and cytokines from basophils and mast cells is a central event in allergic disorders. Several groups of investigators have demonstrated the presence of autoantibodies against IgE and/or FcεRI in patients with chronic spontaneous urticaria. By contrast, the prevalence and functional activity of anti-IgE autoantibodies in atopic dermatitis (AD) are largely unknown. We evaluated the ability of IgG anti-IgE from patients with AD to induce the in vitro IgE-dependent activation of human basophils and skin and lung mast cells. Different preparations of IgG anti-IgE purified from patients with AD and rabbit IgG anti-IgE were compared for their triggering effects on the in vitro release of histamine and type 2 cytokines (IL-4, IL-13) from basophils and of histamine and lipid mediators (prostaglandin D2 and cysteinyl leukotriene C4) from human skin and lung mast cells. One preparation of human IgG anti-IgE out of six patients with AD induced histamine release from basophils, skin and lung mast cells. This preparation of human IgG anti-IgE induced the secretion of cytokines and eicosanoids from basophils and mast cells, respectively. Human monoclonal IgE was a competitive antagonist of both human and rabbit IgG anti-IgE. Human anti-IgE was more potent than rabbit anti-IgE for IL-4 and IL-13 production by basophils and histamine, prostaglandin D2 and leukotriene C4 release from mast cells. Functional anti-IgE autoantibodies rarely occur in patients with AD. When present, they induce the release of proinflammatory mediators and cytokines from basophils and mast cells, thereby possibly contributing to sustained IgE-dependent inflammation in at least a subset of patients with this disorder.

Autoimmunity, IgE and FcεRI-bearing cells.

Antibody-mediated autoimmune diseases (AAID) involve several isotypes of autoreactive antibodies. In a growing number of AAID, autoreactive IgE are present with a significant prevalence and are often associated with the presence of IgG anti-IgE and/or anti-FcεRIα (high affinity IgE receptor α chain). FcεRI-bearing cells, such as basophils or mast cells, are key players in some of these AAID. Recent advances in the pathophysiology of these diseases led to the passed or current development of anti-IgE strategies that showed very potent effects in some of them. The present review centralizes the information on the relevance of autoreactive IgE and FcεRI-bearing cells in the pathophysiology of different AAID and the ones where the anti-IgE therapeutic strategy shows or may show some benefits for the patients.

An indirect ELISA method for quantitative detection of anti-IgE autoantibodies

Objective The accurate measurement of anti-IgE levels in patients′ serum helps for make diagnosis of chronic urticaria (CU). An indirect ELISA method for quantitative detection of IgG anti-IgE, were established. Methods The serum samples and the clinical data of 75 first-diagnosed CU patients and 120 healthy controls were collected at Shanghai General Hospital during the year of 2018. In the indirect ELISA system to measure the IgG (anti-human IgE), the antigen, Human IgE Myeloma, was coated on the plate; Omalizumab (a humanized anti-human IgE antibody) was the standard, and horse radish peroxidase (HRP)-labeled anti-human IgG was the tracer. The optimum concentrations of serum and HRP-labeled anti-human IgG were determined by chessboard titration, and method evaluation was conducted. The comparison of serum anti-IgE levels in CU patients and healthy people were analyzed by Mann-Whitney U test and chi-square test. Receiver operating characteristic (ROC) curves were applied to establish the diagnostic performance of serum anti-IgE for CU. Results The coating concentration of IgE was 5.0×10-4 mg/ml; serum dilution was 1∶300; enzyme-labeled antibody dilution was 1∶100 000. Standard curve was in good linearity with R2=0.996. The intra-and inter-assay coefficient of variation were 3.9%-7.5% and 6.0%-8.2%, and the recovery rate of low and high concentration samples were 95.9% and 108.4%, respectively. When hemoglobin≤1.3 g/L, triglyceride≤4.6 mmol/L, bilirubin≤171 μmol/L, no interference were observed. The limit of blank, limit of detection, and limit of quantitation were 5.8×10-4, 1.8×10-3, and 2.0×10-3 mg/ml. The linearity range was from 2.0×10-3 to 354.4 mg/ml. No Hook effect was found until anti-IgE reached 354.4 mg/ml. The anti-IgE remained stable after serum storage at 4 ℃ overnight or treated with 6 repeated freeze-thaw cycles. The anti-IgE levels in CU patients [19.0(1.9, 58.6)mg/ml] were significantly higher than those in healthy controls [0.7(0.002, 11.1)mg/ml] with P<0.001. When cut-off value was set as 15.3 mg/ml, in this method, the positive rate of CU patients (54.7%) was significantly higher than these of healthy controls (18.3%) (P<0.001, AUC=0.736). Conclusions The indirect ELISA method for serum anti-IgE measurement was successfully established. Anti-IgE autoantibodies in serum would be used in the diagnosis of CU. Key words: Immunoglobulin E; Autoantibodies; Enzyme-linked immunosorbent assay; Urticaria

Biomarkers and clinical characteristics of autoimmune chronic spontaneous urticaria: Results of the PURIST Study.

Autoimmune chronic spontaneous urticaria (aiCSU) is an important subtype of chronic spontaneous urticaria (CSU) in which functional IgG autoantibodies to IgE or its high-affinity receptor (FcεRI) induces mast cell degranulation and subsequent symptom development. However, it has not been tightly characterized. This study aimed to better define the clinical and immunological features and to explore potential biomarkers of aiCSU. This was a multinational, multicenter study of 182 CSU patients. The clinical features studied included: urticaria activity and impact (UAS7 and quality of life); autologous serum skin test (ASST); IgG anti-FcεRI and IgG anti-IgE; IgG-anti-thyroperoxidase (IgG anti-TPO); total serum IgE; and basophil reactivity (BASO) using the basophil activation test (BAT) and basophil histamine release assay (BHRA). Of the 182 patients, 107 (59%) were ASST+, 46 (25%) were BASO+, and 105 (58%) were IgG anti-FcεRI+/IgE+. Fifteen patients (8%) fulfilled all three criteria of aiCSU. aiCSU patients appeared more severe (UAS7 21 vs 9 P<0.016) but showed no other clinical or demographic differences from non-aiCSU patients. aiCSU patients also had markedly lower total IgE levels (P<0.0001) and higher IgG anti-TPO levels (P<0.001). Of biomarkers, positive BAT and BHRA tests were 69% and 88% predictive of aiCSU, respectively. aiCSU is a relatively small but immunologically distinct subtype of CSU that cannot be identified by routine clinical parameters. Inclusion of BHRA or BAT in the diagnostic workup of CSU patients may aid identification of aiCSU patients, who may have a different prognosis and benefit from specific management.

Autologous serum skin test for evaluation of chronic idiopathic urticaria patients: a tertiary hospital study from central India

Background: Majority of patients with chronic urticaria, having no definite etiology are considered chronic idiopathic urticaria (CIU). In recent years, relatively significant number of chronic idiopathic urticaria patients has been classified as having autoimmunity on the basis of presence of auto antibodies (IgG anti IgE receptor alpha subunit or less frequently IgG anti IgE itself) which are responsible for mast cell and basophil activation. Material and Methods: A hospital based crosssectional study was carried out in the Department of Skin, Chirayu Medical College and Hospital, Bhopal located in central India, during the period from August 2012 to February 2014 after institutional ethics committee approval. Total 53 Patients in the age range of 16 to 65 years of CIU were enrolled for study after detailed clinical history and physical examination. Results: Out of total 53 patients, 23(43.39%) showed wheal/ swelling of 1.5 mm or larger at test site as compared to that of control site, thus considered as ASST positive. Duration of CIU ranged from 4 months to 11 years with mean duration of 6.13±2.25 years. 19(82%) of the patients had lesions over whole body whereas only 4(17%) had lesions over face and limbs. 10(43%) patients had angioedema and 14(60%) had dermographism. Conclusion: ASST is simple, cheap and effective diagnostic method to detect presence of autoimmunity in CIU patients thus helps in identifying severity of disease and to choose appropriate therapeutic options accordingly. Our study did not elicit distinct clinical parameters of CIU (except number of wheals/ swelling and frequency of lesions, though statistically not significant) in ASST positive patients from those patients who didn’t show ASST positivity.

Transplacental passage of IgG anti-IgE/IgE immune complexes (HYP7P.306)

Abstract Maternal IgG mediates the transplacental passage of several antigens; however, it is unclear if maternal IgE may be transferred across the placenta as IgG anti-IgE/IgE immune complexes. In this study, we determined maternal and cord blood serum concentrations of IgG anti-IgE/IgE immune complexes in a cohort of allergic and non-allergic mother/infant dyads. We found a strong correlation (r = 0.88) between maternal and cord serum concentrations, which is strongly suggestive of placental transmission. Subclass analysis demonstrated the majority of IgG anti-IgE/IgE immune complexes in maternal sera were of the IgG1 and IgG4 subclasses, while those in cord blood were of the IgG1 subclass. Levels of IgG1 anti-IgE/IgE immune complexes were significantly higher in allergic vs. non-allergic pregnant women. To investigate the role of FcRn in the transplacental passage of IgG anti-IgE/IgE immune complexes, we used MDCK cells stably transfected with hFcRn. IgG, IgG anti-IgE, and IgG anti-IgE/IgE immune complexes bound to hFcRn-expressing MDCK cells in a pH-dependent manner whereas IgE alone did not. The addition of an FcRn blocking antibody effectively inhibited the binding of IgG anti-IgE/IgE immune complexes. Ongoing experiments are being conducted using the MDCK cells to demonstrate FcRn-mediated transcytosis. The ability of maternal IgG anti-IgE/IgE immune complexes to bind fetal myeloid dendritic cells and regulate FcεRI-dependent pro-inflammatory responses is being investigated.

Antibody against immunoglobulin E contained in blood components as causative factor for anaphylactic transfusion reactions

Determining the mechanism underlying the development of transfusion reactions is important in transfusion therapy. Two bags of fresh-frozen plasma obtained from a donor (index donor) were implicated in two cases of anaphylactic transfusion reactions. The serum prepared from the index donor plasma transfused into the second patient (Patient 2) was evaluated using cord blood-derived mast cells (CBMCs) incubated with Patient 2 plasma. The component in the serum required for the degranulation was determined and quantified by chromatography in combination with degranulation assay, Western blot analysis, and enzyme-linked immunosorbent assay. The component in the plasma required for CBMC sensitization was determined using human immunoglobulin (Ig)E or normal plasma in place of Patient 2 plasma in the assay. Sera collected from the index donor between 2001 and 2008 were examined for the CBMC degranulation factor. The donor serum activated CBMCs incubated with Patient 2 plasma. The IgG fraction of the donor serum induced degranulation of CBMCs sensitized with IgE or plasma containing a normal IgE concentration. The IgG anti-IgE at a concentration higher than 2200 ng/mL, which showed CBMC degranulation activity, was detected in the donor sera for at least 7 years. Transfusion of a high concentration of the anti-IgE in the donor plasma was suggested to induce mast cell degranulation in the patients leading to the development of anaphylactic transfusion reactions. Antibodies existing in not only the patient circulation but also the transfused blood might cause transfusion-induced anaphylaxis.

Pathogenesis of chronic urticaria

Chronic urticaria is defined as the presence of urticaria (hives) for at least 6 weeks with the assumption that it occurs daily or close to it. If we eliminate physical urticarias and urticarial vasculitis from consideration, the remainder can be divided into autoimmune chronic urticaria (45%) and idiopathic chronic urticaria (55%). The autoimmune subgroup is associated with the IgG anti-IgE receptor alpha subunit in 35-40% of patients and IgG anti-IgE in an additional 5-10%. These autoantibodies have been shown to activate blood basophils and cutaneous mast cells in vitro with augmentation of basophil activation by complement and release of C5a, in particular. Binding methods (immunoblot and ELISA) yield positives in many autoimmune diseases as well as occasional normal subjects or patients with other forms of urticaria but most such sera are non-functional. Activation of basophils or mast cells causing histamine release is quite specific for chronic urticaria and defines the autoimmune subgroup. Although pathogenicity is not formally proven, the antibodies cause wealing upon intradermal injection, and removal of the autoantibody leads to remission. A cellular infiltrate is seen to be characterized by mast cell degranulation and infiltration of CD4+ T lymphocytes, monocytes, neutrophils, eosinophils, and basophils. The intensity of the infiltrate and clinical severity of the disease (including accompanying angio-oedema) is more severe in the autoimmune subpopulation. This latter group also has a higher evidence of human leucocyte antigen DR alleles associated with autoimmunity and a 25% incidence of antithyroid antibodies with diagnosed hypothyroidism in some. Hypo-responsiveness of patients' basophils to anti-IgE and hyperresponsiveness to serum defines another subpopulation (at least 50%) that overlaps the idiopathic and autoimmune subgroups. Hypo-responsiveness to anti-IgE has been shown to be associated with elevated levels of cytoplasmic phosphatases that inhibit degranulation. Reversal of the abnormality is seen with disease remission. Further work will be needed to distinguish whether this is a cause or a consequence of persistent urticaria and to further assess the relationship (or lack thereof) of altered responsiveness (decreased or increased) with the presence or absence of activating autoantibodies.

Presence of IgG Anti-IgE Autoantibodies in Chronic Urticaria and Atopic Dermatitis

RATIONALE: Autoantibodies specific for IgE have been detected in multiple disease states. In chronic urticaria (CU) a subset of patients have an autoimmune etiology with auto-antibodies against IgE, FceRI or FceRII. IgE autoantibodies have also been described in atopic dermatitis (AD). It has been suggested that these autoantibodies may inhibit the inflammatory cascade. The autoantibodies may bind to the surface of mast cells and basophils initiating a signal transduction cascade that results in the secretion of histamine and other mediators and the amplification of ongoing allergic reactions. The goal was to develop and standardize a quantitative assay for these autoantibodies.METHODS: IgG antibodies specific for IgE are quantified a non-competitive ELISA. The assay calibration curve was based on standards prepared from a humanized monoclonal anti-IgE. The test was evaluated with sera from autoimmune CU (n = 97), idiopathic CU (n = 142), AD (n = 75) patients and healthy controls (n = 61).RESULTS: A population of healthy controls was used to determine the cutoff for the assay. The 95% cutoff was 60ng/mL. The assay demonstrated high reproducibility (intra- (7.4%) and inter-assay (10%)) and good linearity (inter-dilutional coefficient of variation of 14%). This study confirmed the presence of autoantibodies in healthy individuals (mean = 16.1). Patients with autoimmune CU and AD had higher rates of samples with elevated anti-IgE, 20.6% and 29.3% compared to healthy controls (3.3%) and idiopathic CU patients (4.9%).CONCLUSIONS: A quantitative assay can be useful for the detailed evaluation of autoantibodies against IgE in diseases such as autoimmune chronic urticaria, atopic dermatitis, allergic rhinitis, and idiopathic rhinitis. RATIONALE: Autoantibodies specific for IgE have been detected in multiple disease states. In chronic urticaria (CU) a subset of patients have an autoimmune etiology with auto-antibodies against IgE, FceRI or FceRII. IgE autoantibodies have also been described in atopic dermatitis (AD). It has been suggested that these autoantibodies may inhibit the inflammatory cascade. The autoantibodies may bind to the surface of mast cells and basophils initiating a signal transduction cascade that results in the secretion of histamine and other mediators and the amplification of ongoing allergic reactions. The goal was to develop and standardize a quantitative assay for these autoantibodies. METHODS: IgG antibodies specific for IgE are quantified a non-competitive ELISA. The assay calibration curve was based on standards prepared from a humanized monoclonal anti-IgE. The test was evaluated with sera from autoimmune CU (n = 97), idiopathic CU (n = 142), AD (n = 75) patients and healthy controls (n = 61). RESULTS: A population of healthy controls was used to determine the cutoff for the assay. The 95% cutoff was 60ng/mL. The assay demonstrated high reproducibility (intra- (7.4%) and inter-assay (10%)) and good linearity (inter-dilutional coefficient of variation of 14%). This study confirmed the presence of autoantibodies in healthy individuals (mean = 16.1). Patients with autoimmune CU and AD had higher rates of samples with elevated anti-IgE, 20.6% and 29.3% compared to healthy controls (3.3%) and idiopathic CU patients (4.9%). CONCLUSIONS: A quantitative assay can be useful for the detailed evaluation of autoantibodies against IgE in diseases such as autoimmune chronic urticaria, atopic dermatitis, allergic rhinitis, and idiopathic rhinitis.

Basophil Phenotypes in Chronic Idiopathic Urticaria in Relation to Disease Activity and Autoantibodies

Potentially pathogenic IgG autoantibodies to IgE or its receptor, Fc epsilonRIalpha, have been detected in approximately 40% of chronic idiopathic urticaria (CIU) patients. CIU patients' basophils display distinct altered Fc epsilonRIalpha-mediated degranulation. CIU patients with basophil histamine release in response to polyclonal goat anti-human IgE > or = 10% are classified as CIU responders (CIU-R) and < 10% are CIU non-responders (CIU-NR). We compared the presence of autoantibodies to basophil degranulation phenotypes and to disease status (active or inactive). Sera were collected from non-CIU subjects and CIU subjects who participated in a longitudinal study of disease severity and had defined basophil degranulation phenotypes. Immunoenzymetric assays (IEMA) quantified IgG anti-Fc epsilonRIalpha and anti-IgE. IgG anti-Fc epsilonRIalpha antibody was detected in 57% of CIU-R (n=35), 55% of CIU-NR (n=29), and 57% of non-CIU subjects (n=23), whereas IgG anti-IgE was present in 43% of CIU-R, 45% of CIU-NR, and 30% of non-CIU subjects. Both the autoantibody levels and the functional basophil phenotype remained stable in subjects with active disease (n=16), whereas there was an enhancement in basophil function as subjects evolved into a state of remission (n=6), which appears independent of the presence of autoantibody. IEMAs detected a similar frequency of autoantibodies in CIU-R, CIU-NR, and non-CIU subjects. Basophil function may be independent of IEMA-detected autoantibodies.

IgG Anti-IgE Autoantibodies in Visceral Leishmaniasis

Procedures for IgG depletion in visceral leishmaniasis (VL) and schistosomiasis sera using Sepharose-protein G beads also deplete IgE. In this study, the presence of IgG anti-IgE autoantibodies in sera from patients with VL (n = 10), and hepatic-intestinal schistosomiasis (n = 10) and from healthy individuals (n = 10) was investigated. A sandwich ELISA using goat IgG anti-human IgE to capture serum IgE and goat anti-human IgG peroxidase conjugate to demonstrate the binding of IgG to the IgE captured was performed. VL sera had higher titers (p < 0.05) of IgG anti-IgE autoantibodies (OD = 2.01 +/- 0.43) than sera from healthy individuals (OD = 1.35 +/- 0.16) or persons infected with Schistosoma mansoni (OD = 1.34 +/- 0.18). The immunoblotting carried out with eluates from Sepharose-protein G beads used to deplete IgG from these sera and goat anti-human IgE peroxidase conjugate, showed a similar pattern of bands, predominating the 75 kDa epsilon-heavy chain and also polypeptides resulting from physiological enzymatic digestion of IgE. A frequent additional band immediately above 75 kDa was observed only in VL sera.

Auto IgG anti-IgE and IgG × IgE immune complex presence and effects on ELISA-based quantitation of IgE in canine atopic dermatitis, demodectic acariasis and helminthiasis

Atopic dermatitis is a common allergic disease manifestation in dogs; however, there is no correlation between clinical disease and detectable total serum IgE. Auto antibodies of the IgG subclass against IgE may affect the detection of serum IgE by immunoassay and may be important in the regulation of IgE production by B cells. ELISA were developed to detect serum antibodies specific for IgE using a newly available canine monoclonal IgE of known antigen specificity, generated from a canine × murine heterohybridoma. To test for correlation of auto IgG anti-IgE levels with manifestation of atopic dermatitis, the sera from 101 atopic dogs were compared with sera from non-atopic dogs of various breeds, foxhounds manifesting clinical signs of demodectic acariasis and helminth parasitized random bred dogs for quantities of IgG anti-IgE measured in units/ml compared to a high titer standard serum. To test for serum effects on quantitation of IgE, known amounts of canine monoclonal IgE were added to various sera and measured by capture ELISA with detecting monoclonal antibodies specific for heat labile or heat stabile epitopes. Unheated sera from dogs manifesting clinical atopic dermatitis and helminth parasitized dogs had levels of IgG anti-IgE that were significantly lower than various breeds of dogs not manifesting dermatologic lesions and foxhounds manifesting demodectic acariasis. Heating sera at 56°C for 3 h to denature the high affinity binding site on the IgE heavy chain caused a marked increase over non-heated sera in detectable IgG angi-IgE in almost all dogs. This increase was most profound in helminth-infected dogs and foxhounds manifesting demodectic mange with 7 fold increases each, respectively, and in atopic dogs with a 5 fold increase compared to 3 fold increases for clinically-normal springer spaniels and all soft coated wheaten terriers. The terriers demonstrated an association of lower heated serum values of IgG anti-IgE with manifestation of a familial syndrome of protein-losing enteropathy and protein-losing nephropathy. The ability of mouse anti-canine IgE monoclonal antibodies specific for either heat labile or heat stabile epitopes to detect canine monoclonal IgE added to sera in known amounts varied from serum to serum and at different concentrations of the same serum, but did not correlate with IgG anti-IgE values for these sera. The range of absolute levels of serum IgE in dogs showing little or no inhibition of detection of added IgE was < 0.5 ng/ml to 2 μg/ml. It was concluded that the increase in detectable IgG anti-IgE after heating sera indicates that IgG × IgE immune complexes are normally present in most dogs; however, the increase over uncomplexed IgG anti-IgE was most pronounced in dogs manifesting atopic dermatitis and demodectic acariasis. A quantitative comparison of IgG anti-IgE or IgG × IgE to total serum IgE was not made because the ability of monoclonal antibodies specific for either heat labile or heat stable epitopes on the IgE heavy chain to detect IgE added to serum, as well as innate serum IgE, was highly variable in different dilutions of serum from individual to individual.

Assessment of autoimmunity in patients with chronic urticaria

Background: The etiology of chronic urticaria is unknown, and an exogenous allergen cannot be identified as the cause in the vast majority of subjects. Thus the concept has evolved that it might be autoimmune. Objective: We have prospectively assessed sera obtained from 50 consecutive patients with chronic urticaria for the presence of autoantibodies that could be pathogenic. Methods: We tested sera for their ability to release histamine from human basophils and to activate rat basophil leukemia cells that were transfected with the α subunit of the IgE receptor. We also tested selected sera for anti-IgE antibodies and for IgG anti-FcϵRIα by Western blot. Results: Sera from 38 of 50 patients with chronic urticaria released β-hexosaminidase from transfected rat basophil leukemia cells, whereas only one of 20 control sera did so ( p < 0.001); in 30 subjects this could be attributed to IgG anti-FcϵRIα. When human basophils were used, sera from 20 of 50 patients with chronic urticaria released a significant quantity of histamine compared with one of 20 control subjects ( p < 0.01). Six patients with chronic urticaria and one control subject had IgG anti-IgE. In selected sera we could demonstrate IgG anti-FcϵRIα by Western blot; however, some sera are positive for histamine release but do not demonstrate such binding. Conclusion: A large fraction of patients with chronic urticaria have antibody directed to FcϵRIα that is functional (60%). A smaller number have IgG anti-IgE (10%). A third group may also have circulating factors capable of activating basophils or mast cells of which the identity is unknown. Thus chronic urticaria may be autoimmune in origin. (J Allergy Clin Immunol 1997;99:461-5.)

Circulating IgG autoanti-IgE antibodies in atopic patients block the binding of IgE to its low affinity receptor (CD23)

Aims-To investigate the ability of circulating IgG autoanti-IgE antibodies from atopic rhinitis patients to block the binding of IgE to its low affinity receptor (FcepsilonRII), also termed CD23.Methods-This involved the use of a well validated flow cytometric method to detect inhibition of FITC labelled IgE binding to human B cells expressing CD23 (RPMI 8866 cell line).Results-Taking inhibition values greater than 20% as being significant, 15 out of 20 IgG anti-IgE containing sera inhibited the binding of IgE-FITC to the RPMI 8866 cells. The inhibitory effect was recoverable in the IgG fraction of serum, but was not related to the titre of either IgG1 anti-IgE or IgG4 anti-IgE, thus suggesting that it might be related to epitope specificity. No such inhibition was demonstrable with rheumatoid sera containing autoanti-IgG (that is, rheumatoid factor), but lacking autoanti-IgE.Conclusions-The capacity of anti-IgE to block the binding of IgE to CD23 has important implications, particularly in terms of upregulation of IgE synthesis and the consequent perpetuation of the inflammatory response.

Do autoantibodies to IgE play a role in IgE‐mediated events?

Elevated blood levels of IgG anti-IgE are detectable in individuals exhibiting enhanced IgE production, namely those with allergic conditions and helminthic parasite infections. The fact that there are epitope-specific subpopulations of autoanti-IgE suggests that this autoantibody could potentially have multiple effects in immunological events involving IgE.

High anti‐IgE levels at birth are associated with a reduced allergy prevalence in infants at risk: a prospective study

Development of atopic disease was prospectively studied in 148 children from birth to the age of 18 months and related to serum levels of IgG anti-IgE antibody. Children with a dual heredity of allergy, but remaining healthy, had significantly higher IgG anti-IgE levels at birth than children with a similar predisposition to allergy, who became allergic. Children with increased allergy risk, defined by elevated IgE levels at birth (> = 0.53 kU/l) and with probable allergy symptoms had also significantly higher IgG anti-IgE levels at birth than children of the same risk group, developing definite allergy. Independent of allergy risk, there was a significantly lower prevalence of atopic disease in children with cord serum levels of IgG anti-IgE above 350 AU/l than in children with lower levels. Additionally, we showed that the allergy predictive capacity of IgE levels in cord serum was slightly improved in specificity, sensitivity and efficiency by including not only the family history of allergy, but also cord serum levels of IgG anti-IgE. Our results thus raise the possibility that high levels of IgG anti-IgE protect children of increased allergy risk from early development of atopic disease and reduce the severity of symptoms.

In vitro basophil histamine-releasing activity of circulating IgG1 and IgG4 autoanti-IgE antibodies from asthma patients and the demonstration that anti-IgE modulates allergen-induced basophil activation.

In this study we have examined the relationship between the in vitro basophil histamine-releasing activity of human IgG anti-IgE, isolated as euglobulin fractions from sera of asthmatic patients, and its IgG1/IgG4 subclass distribution. In particular, we have investigated whether IgG anti-IgE modulates allergen-induced basophil activation. The study has revealed that only a small proportion of IgG anti-IgE samples triggered histamine release from basophils of an asthmatic individual (4/21; 19%), a hay fever sufferer (4/10; 40%) and a healthy person (7/21; 33%). The basophil histamine-releasing activity of IgG anti-IgE did not seem to be determined by the IgG1/IgG4 subclass composition of the IgG anti-IgE preparation used. Furthermore, we have demonstrated that autoanti-IgE antibodies modulate allergen-induced basophil histamine release. The three modulatory effects exerted by IgG anti-IgE antibodies on allergen-triggered basophil activation (i.e. additive, synergistic and blocking) were not dependent on the subclass nature of IgG anti-IgE or the use of histamine-releasing anti-IgE preparations. Our data suggest that IgG anti-IgE antibodies in asthma patients may consist of two functionally distinct subpopulations: those which up-regulate (pro-allergic) and those which down-regulate (anti-allergic) the allergic release of mediators from mast cells and basophils.

The detection of autoantibodies to IgE in plasma of individuals infected with hookworm (Necator americanus) and the demonstration of a predominant IgG1 anti‐lgE autoantibody response

In this study we have demonstrated significantly elevated levels of circulating IgG autoanti-IgE antibody in hookworm infected individuals from Kebasob village on Karkar Island, Papua New Guinea. Although anti-IgE activity was demonstrable in IgG1, IgG3 and IgG4, IgG1 was by far the most important subclass of IgG anti-IgE in terms of frequency of detection (34/39; 87.2%) and magnitude of increase (P = 0.0000); with IgG3 (16/39; 41.0%) and IgG4 (15/39; 38.5%) antibodies being considerably less prevalent. Plasma levels of IgG1 anti-IgE (P = 0.0019) and IgG3 anti-IgE (P = 0.0034) showed significant correlations with total IgE concentrations, but not with IgE specific to excretory-secretory worm products; thus suggesting that anti-IgE synthesis is more related to polyclonal hyper IgE production than to antigen-specific IgE stimulation. No correlation was seen between IgG subclass anti-IgE levels and faecal egg counts or worm burden. Given that our data failed to show a negative or a positive correlation between anti-IgE and the degree of infection with hookworm, it is tempting to speculate that the main role of autoanti-IgE is to provide the host with protection against immune complex- and IgE-mediated hypersensitivity reactions to parasitic antigens.