Detection of IgG subclass-specific anti-IgE antibodies in normal and atopic individuals

Atopic dermatitis and atopic asthma patients were shown to have elevated IgG anti-IgE levels compared with those of controls. When the pattern of IgG subclass anti-IgE activity was studied, further differences between the three groups became apparent. Adults with atopic dermatitis had elevated IgG1 and IgG4 anti-IgE compared with those of controls but no corresponding increase in the IgG2 or IgG3 subclasses. For Sri Lankan children with atopic asthma and a high incidence of Nematoda infection, elevated anti-IgE was restricted to the IgG1 subclass. While IgG1 anti-IgE proved to be the predominant subclass for both atopic groups, IgG2 anti-IgE was the major subclass among controls.     

Altered distribution of IgG subclasses in aspirin-induced asthma: high IgG4, low IgG1

We have determined IgG subclass concentrations in 100 patients with aspirin-induced asthma and 80 healthy controls. Patients on chronic corticotherapy (n = 64) had significantly lower total IgG levels than patients not receiving steroids (n = 36) or controls. Corticotherapy was not associated with changes in the subclass distributions. In patients, the most striking finding was elevation of IgG4. It was not related to corticotherapy or serum IgE levels. The rise in IgG4 was accompanied by a modest, though statistically significant, depression of IgG1. No changes of IgG2 and IgG3 concentrations were observed. Thus, aspirin-induced asthma is characterized by a distinct pattern of distributions of IgG subclasses. It is suggested that in aspirin-induced asthma elevation of IgG4 might result from chronic antigenic stimulation, of viral origin, and that determination of IgG subclass distribution might be of clinical interest.     

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 profile of IgG and IgG subclasses of onchocerciasis patients.

In this study Onchocerca gutturosa was compared with O. volvulus in an ELISA test to detect Onchocerca-specific IgG and IgG subclasses. The test was developed and standardized to detect Onchocerca-specific IgG and IgG subclasses in sera of onchocerciasis patients and endemic controls. Onchocerca volvulus and O. gutturosa crude water-soluble antigens showed no significant difference in detecting onchocerca-specific IgG antibody (T = 1.88, P greater than 0.05). The levels of IgG subclasses varied greatly. IgG4 showed the highest detected mean level (0.84 +/- 0.59) and the other three subclasses showed considerably lower mean levels (IgG1 = 0.27 +/- 0.16, IgG2 = 0.24 +/- 0.17, IgG3 = 0.28 +/- 0.12). The status and score of skin lesions were found to have significant effect on the IgG and IgG subclasses levels (all P less than 0.001). IgG4 showed a positive correlation with the microfilarial (Mf) load (r = 0.21, P less than 0.03). IgG3 levels have a significant negative correlation with the Mf load (r = -0.23, P less than 0.02). The biological significance of these IgG and IgG subclasses in onchocerciasis is discussed.     

Isotype and IgG Subclass Distribution of Autoantibody Response to Alpha-enolase Protein in Adult Patients with Severe Asthma

Purpose

A possible involvement of autoimmune mechanism in the pathogenesis of bronchial asthma has been proposed. Recently, alpha-enolase protein was identified as a major autoantigen recognized by circulating IgG autoantibodies in patients with severe asthma. To evaluate a possible pathogenetic significance of these autoantibodies in severe asthma, isotype (IgG, IgA, IgM, and IgE) and IgG subclass (IgG1, IgG2, IgG3, and IgG4) distributions of autoantibodies to recombinant human alpha-enolase protein were analyzed.

Patients and Methods

We examined serum samples from 10 patients with severe asthma and 7 patients with mild-to-moderate asthma, and 5 healthy controls by immunoblot analysis. Severe asthma was defined as patients having at least 1 severe asthmatic exacerbation requiring an emergency department visit or admission in the last year despite continuous typical therapies.

Results

IgG1 was the predominant IgG subclass antibody response to alpha-enolase protein in patients with severe asthma. IgG1 autoantibody to alpha-enolase protein was detected in 7 of 10 patients with severe asthma (70%), 1 of 7 patients with mild-to-moderate asthma (14.3%), and none of 5 healthy controls (0%) (chi-square test; p < 0.05). IgA, IgM, and IgE autoantibodies to alpha-enolase protein could not be detected in patients with severe asthma.

Conclusion

IgG1 subclass was the predominant type of autoantibody response to alpha-enolase protein in patients with severe asthma, suggests a possibility of IgG1 autoantibody-mediated complement activation in the pathogenesis of severe asthma.     

Evaluation of immunotherapy-induced changes in specific IgE, IgG and IgG subclasses in birch pollen allergic patients by means of immunoblotting

Sera from 27 birch pollen-allergic patients who had undergone hyposensitization treatment for 22-41 months were studied by immunoblotting before and after therapy, whereby the levels of IgE, IgG and IgG1-4 antibodies directed against the major allergen Bet v I and minor allergens of birch pollen were monitored. The clinical benefit of immunotherapy (IT) was evaluated using a symptom specific questionnaire. In patients with good clinical response (responders, n = 18), as defined by improvement of symptoms, anti-Bet v I IgE antibodies were found to decrease in 10/18 patients (55.5%), whereas in 6/18 (33.3%) no change and in two cases (11.2%) an increase of specific IgE was observed. In the group of patients with unsatisfactory clinical outcome (non-responders, n = 9), 3/9 patients (33.3%) showed a decrease, 3/9 (33.3%) no change and 3/9 (33.3%) an increase in levels of IgE antibodies directed against Bet v I. In the case of minor allergens, 5/18 responders (27.7%) and 8/9 non-responders (88.8%) showed specific IgE before IT. In the responder group, no increase of specific IgE could be observed after IT. In non-responders, however, an increase of IgE directed against minor allergens was seen in 3/9 patients (33.3%). In all patients, regardless of therapeutical success, IT-induced elevated levels of specific IgG, IgG1 and in particular IgG4 directed against Bet v I were found. Regarding minor allergens, a heterogeneous pattern of IgG responses without significant correlation to clinical benefit was observed. Our results indicate that changes in IgG reactivity patterns against Bet v I and minor allergens, as shown by the immunoblot technique, did not correlate with good or bad clinical outcome.     

Circulating IgG autoantibodies to IgE in atopic syndromes

Sera from nonatopic healthy donors and patients with hyper-IgE syndrome, allergic respiratory disease, i.e., allergic rhinitis and asthma, and atopic dermatitis were assayed for the presence of IgG and IgM antibodies to IgE. The assay used was based on an ELISA method that measured the binding of IgG or IgM in test sera to myeloma IgE (PS)-coated microtiter wells. The levels of IgG anti-IgE but not of IgM anti-IgE were elevated in patient sera of all three categories tested. The same sera failed to demonstrate increased levels of IgG anti-IgM or IgG anti-IgA. Significant IgG anti-IgE activity remained after absorption of patient sera over pooled human IgG F(ab')2 Sepharose. The IgG anti-IgE activity appeared to be directed toward the Fc portion of IgE because absorption of positive sera over IgE (ADZ) Sepharose but not over myeloma IgG Sepharose completely removed their reactivity with IgE (PS) and because sera from atopic individuals but not from normal subjects contained IgG anti-IgE activity against the protein backbone of the Fc portion of IgE synthesized from a fragment of the cloned gene of human myeloma IgE (ND) heavy chain. Regression analysis demonstrated a weak but significant correlation (r = 0.31; p less than 0.05) between serum IgE levels and IgG anti-IgE activity. Fractionation of sera from the three patient categories by gel filtration over Sepharose 6B revealed that IgG anti-IgE activity was present both as monomeric IgG and in IgE containing immune complexes (IC). Intermediate molecular size IC (between 7S and 19S) were present in all three patient groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

The significance of blood levels of IgM,IgA, IgG and IgG subclasses in Sudanese visceral leishmaniasis patients

We developed an ELISA test using leishmania antigenic extracts to detect antigen-specific antibody responses, including subclass and isotype analysis, in visceral leishmaniasis (VL) patients from the Sudan. A total of 92 parasitologically proven patients were compared with cutaneous leishmaniasis, schistosomiasis, malaria, onchocerciasis and tuberculosis patients, as well as with healthy endemic and non-endemic controls. Some VL patients were examined before and after chemotherapy. VL patients showed significantly higher IgG responses compared with all other groups (93·4% sensitivity, 93·7% specificity), and higher (but not significantly) IgM responses. All groups showed low IgA levels. All groups showed low IgA levels. All IgG subclasses, IgG1, 2, 3, and 4, showed higher levels in patients than all other groups, with IgG1 and IgG3 levels being significantly reduced following treatment. The rank order for specificity and sensitivity for IgG subclasses was IgG3 > IgG I> IgG2> IgG4.     

Distribution of IgG subclasses in antimonial unresponsive Indian kala-azar patients

Sodium antimony gluconate (SAG) is the mainstay of treatment for visceral leishmaniasis (VL) or kala-azar. In view of the increasing incidence of refractoriness to SAG in India, we compared the levels of parasite-specific IgG and IgG subclasses in 20 longitudinally followed up kala-azar patients. In both SAG-responsive (n = 10) and unresponsive patients (n = 10), the levels of total IgG, IgG1, IgG2, IgG3 and IgG4 were increased, the rank order being IgG1 > IgG2 > IgG3 = IgG4. Following treatment, a significant decrease in total IgG and the four subclasses occurred in the SAG-responsive group, whereas in the SAG-unresponsive group these levels were unchanged or slightly increased. Therefore, monitoring of IgG1 and IgG2 levels in Indian kala-azar patients is a good serologic alternative to monitoring the disease status.     

Prevalence and subclass distribution of IgG-anti-IgE autoantibodies in atopy and parasitosis.

Using immunoblotting, we investigated sera of 60 patients with atopic dermatitis, 12 patients with helminth infections and 36 nonallergic controls, for anti-IgE autoantibodies. We found IgG anti-IgE autoantibodies in 62% of the atopics, 42% of the patients with parasitosis and 11% of the controls. IgG anti-IgE occurred most often (94%) in patients with atopic dermatitis plus additional atopic disorder, such as allergic asthma and rhinoconjunctivitis. In parallel, we found a significantly higher occurrence of IgG anti-IgE in the patients with high IgE levels compared to patients with low IgE levels (p less than 0.0005). The predominant subclasses of anti-IgE autoantibodies were IgG1 and IgG3 in atopy and parasitosis. In the controls, we found IgG4 and IgG3 anti-IgE, but no IgG1 autoantibodies. The frequency of IgG2 anti-IgE was very low; it occurred in 2 patients only. Prevalence and IgG subclass distribution of anti-IgE autoantibodies was found to be different for patients with atopic dermatitis, parasitic infection and for controls.     

Detection of IgG subclasses with anti-IgE activity in patients with atopic diseases.

Significantly increased levels of IgG anti-IgE were seen in atopic patients as compared with controls. A correlation was observed between the levels of anti-IgE autoantibodies and serum IgE in the groups of atopic patients studied. No significant correlation was found between IgG anti-IgE levels and severity of the disease or between IgG subclasses with anti-IgE activity and clinical status. Analysis of IgG subclasses with anti-IgE activity showed that IgG1 and IgG4 were clearly factors in differentiating the atopics from the controls. IgG2 and IgG3 anti-IgE levels were not statistically significantly elevated. The lack of these autoantibodies may be explained by the presence of immune complexes or the lack of specificity of the monoclonal antibodies used in this study. These observations have not yet determined whether these autoantibodies and the isotypic selection and restriction observed play a role in the dysregulation of the immune response and in the evolution towards atopy.     

IgG and IgE antibodies to Chironomidae in asthmatic patients.

IgG antibodies to Chironomidae and its correlations to radioallergosorbent and skin reactions were examined with the aim of clarifying the relationship between asthma and Chironomidae. The level of specific IgG antibody in asthmatic patients (0.698 +/- 0.034, n = 104) was significantly greater than that in normal subjects (0.367 +/- 0.032, n = 52) (P less than 0.01). The specific IgG level was not correlated to skin reaction, nor to IgE RAST scores. Specific IgG1 and IgG4 levels in asthmatic patients were significantly greater than in control subjects (n = 14) (P less than 0.01).     

Clinical significance of IgG subclass antibodies to wheat flour antigens in bakers

We measured the IgG subclass antibody levels to wheat flour in 42 bakers and 20 controls with an enzyme immunoassay. The levels of total IgG, IgG1 IgG2 and IgG4 antibodies were significantly higher in the bakers than in the unexposed controls. The presence of anti-wheat flour IgG subclass antibodies in the bakers was correlated with various clinical variables including IgE levels, duration of asthmatic or rhinitis symptoms, skin prick test response, peripheral blood eosinophil levels, bronchial histamine reactivity and responses to nasal challenge with wheat flour. The IgG subclass antibody levels of the total cohort of bakers did not correlate with any of the measured clinical variables. However, among men specific IgG4 and IgG1 antibody levels correlated negatively with total IgE levels and duration of rhinitis, respectively. We conclude that IgG and IgG subclass levels to wheat flour in bakers reflect exposure, but that it is not related to any specific clinical situation. The exact pathogenic role of these antibodies in the development of occupational asthma and rhinitis is thus not clear.     

Specific IgG4 Production during House Dust Mite Immunotherapy among Age, Gender and Allergic Disease Populations

Background: Specific IgG4 induced by allergen-specific immunotherapy (SIT) is an immunological marker related to the appearance of clinical tolerance. But specific IgG4 levels in different age, gender and allergic disease populations have not been fully investigated. Methods: This study involved 226 children and 109 adults with allergic rhinitis and/or asthma receiving a 156-week course of Dermatophagoides pteronyssinus (Der p) subcutaneous SIT. Symptom and medication scores, forced expiratory volume after 1 s (FEV(1)) and Der p-specific IgG4 levels at weeks 0, 5, 10, 25, 52, 104 and 156 were analyzed. Results: Rhinitis symptom and medication scores and FEV(1) % predicted in children showed significantly greater improvement than in adults at week 104 and 156 (p < 0.05). Levels of Der p-specific IgG4 showed a significant increase after 10 weeks of subcutaneous SIT (p < 0.0001) and continued to increase during the 156-week SIT period. Before SIT, the initial Der p-specific IgG4 level was higher in children than adults (p = 0.0004). The increase ratio of Der p-specific IgG4 was higher in children than adults at 52 weeks (p < 0.001) and 104 weeks (p = 0.0156) of SIT, and was higher in rhinitis compared to asthma patients at 156 weeks of SIT (p = 0.0244). There was no difference between males and females at any time points. Conclusion: Children are more responsive to SIT, demonstrating clinical and FEV(1) improvement and producing higher levels of allergen-specific IgG4 during a shorter SIT period compared to adults. Rhinitis patients show a higher increase in specific IgG4 compared to patients with asthma symptoms. The increase of Der p-specific IgG4 reflects a specific response of the immune system towards the SIT vaccine being administrated.     

Clinical characteristics of autoimmune pancreatitis with IgG4 related kidney disease

PurposeTo clarify the clinical characteristics of autoimmune pancreatitis (AIP) in immunoglobulin (Ig)G4-related kidney disease (IgG4-RKD).Patients and methodsA total of 92 patients with AIP were divided into an IgG4-RKD-positive group (RKD-P group, n = 13) and an IgG4-RKD-negative group (RKD-N group, n = 79) on the basis of the diagnostic criteria for IgG4-RKD. Clinical characteristics, including: age; sex; the presence of extrapancreatic lesions other than renal lesions, proteinuria, and hematuria; serum concentrations of IgG, IgG4, IgE, and creatinine; and urinary concentrations of liver-type fatty acid binding protein, α1-microglobulin, β2-microglobulin, and N-acetyl-β-d-glucosaminidase were compared between the RKD-P and RKD-N groups. The clinical course of the RKD-P group was also characterized.ResultsThe prevalence of extrapancreatic lesions other than renal lesions was significantly higher in the RKD-P group (84.6% vs 43.0%,p < 0.01). Serum creatinine (1.19 mg/dl versus 0.74 mg/dl, p < 0.05), urinary β2-microglobulin (6609.8 μg/l vs 265.8 μg/l, p < 0.05), and the prevalence of proteinuria (30.7% vs 7.6%, p < 0.05) were significantly higher in the RKD-P group. Nine out of thirteen patients in the RKD-P group had multiple low-density renal lesions on enhanced computed tomography, 3 patients had multiple high-intensity lesions on diffusion-weighted magnetic resonance images, and 1 patient had diffuse thickening of the renal wall, with a smooth intra-luminal surface.ConclusionsPatients who had AIP with IgG4-RKD were more likely to have extrapancreatic lesions other than those in the kidney, and their serum creatinine and urinary β2-microglobulin concentrations were significantly higher than in those without IgG4-RKD.     

Specific IgE, IgG and IgG4 antibodies against house dust mite in patients with bronchial asthma

Serum levels of total IgE, specific IgE, IgG and IgG4 against house dust mite were measured in mite-sensitive asthma patients receiving immunotherapy with house dust. Serum levels of total IgE, mite specific IgE and IgG did not significantly change during the course of hyposensitization. Increased levels of mite specific IgG4 were observed in patients during immunotherapy. The increase in specific IgG4 was dependent on the total dose of house dust administered in both children (r = 0.636, p less than 0.001) and adults (r = 0.629, p less than 0.01). However, the increase of specific IgG4 in adults was not as apparent as in children. These results might suggest that mite specific IgG4 is a useful immunological marker in the immunotherapy for allergic asthma, and that IgG4 antibody acts as a blocking antibody in atopic bronchial asthma.     

The recognition of a recombinant human Fc epsilon fragment by the subclasses of IgG autoanti-IgE: disproportional subclasses distribution of complexed autoantibody.

Circulating IgG autoanti-IgE is detectable in a large proportion of individuals with allergic asthma where it is suggested to be potentially involved in the removal of IgE-allergen complexes. Since such a putative role will largely be determined by the subclass profile of complexed (i.e. IgE-bound) IgG anti-IgE, a study was undertaken to determine the subclass distribution of complexed IgG anti-IgE antibody in the sera of asthmatic patients. The study exploits the heat-labile property of IgE by heating (30 min at 56 degrees C) serum to liberate bound anti-IgE, pre- and post-heated sera are then assayed for IgG subclass anti-recombinant human Fc epsilon (rFc epsilon) activities by ELISA and any heat-induced increase in antibody activity is taken as a measure of complexed anti-IgE. This has revealed a disproportionately high amount of IgG4 in complexed (but not free) IgG anti-IgE. The propensity of IgG4 to form complexes with IgE has important biological consequences, particularly with regard to the activation of C1q and Fc gamma R by other subclasses.     

Specificity of IgG subclass antibodies in different clinical manifestations of leprosy.

We analysed specific IgG subclasses levels to Mycobacterium leprae sonicate extract (MSE), lipoarabinomannan B (LAM) and phenolic glycolipid I (PGL-I) in the sera of leprosy patients with different clinical manifestations. IgG2 was found to be the predominant antibody to MSE regardless of clinical manifestations, and IgG1 response was mostly seen in lepromatous patients. IgG3 reacted only rarely but IgG4 reacted relatively more in certain clinical groups such as borderline lepromatous and lepromatous with erythema nodosum leprosum (ENL) reaction. Most of the IgG subclass responses to MSE could be accounted for reactivity with LAM, suggesting that LAM is the major immunogen involved in the pathogenesis of leprosy. In contrast to LAM, PGL-I antigen showed considerably lower reactivities for IgG subclasses. An association between IgG subclass responses and clinical manifestations of leprosy was also seen. Whereas borderline lepromatous patients were found to have significantly higher levels of IgG2 and IgG4 to MSE, lepromatous patients had elevated levels of IgG1 and lower levels of IgG2. An interesting observation, however, was the significantly higher levels of IgG2 to LAM in the pure neuritic leprosy patients.     

The natural history of Apis-specific IgG and IgG4 in beekeepers

Background Most published studies on changes of specific IgG or its subclasses as a response to stimuli by allergens have been performed on patients under immunotherapy. There are few reports analysing the response to immunoglobulins in patients exposed to allergens in their natural habitats. Objective The aim of this work was to discover the natural history of Apis specific IgG (IgG-ap) and IgG4 (IgG4-ap) levels in beekeepers from the Canary Islands. Methods We studied 242 beekeepers (Bks). We used a questionnaire and measured total IgE and seric Apis specific IgE (IgE-ap), IgG-ap and IgG4-ap against Apis mellifera venom. Results All Bks had IgG-ap and IgG4-ap. IgE-ap was positive in 160 Bks (65.6 %), but only 92 (37.6 %) Bks were considered sensitized. IgG-ap and IgG4-ap showed significant correlation (r = 0,84); IgE did not correlate with IgG-ap or IgG4-ap. There was no seasonal variation in IgG-ap or IgG4-ap. The group of sensitized Bks had significantly lower IgG-ap and IgG4-ap levels (P < 0.05). The groups with longer beekeeping activity showed significantly higher levels of IgG-ap and IgG4-ap (P < 0.001). Bks with locals reactions had significantly higher IgG-ap and IgG4-ap than Bks who reported systemic reactions (P < 0.05). Conclusion Our study showed that IgG-ap and IgG4-ap appear to increase in Bks, either according to their beekeeping experience or in subjects with local reactions after bee stings.     

Ovalbumin-specific immunoglobulin G and subclass responses through the first 5 years of life in relation to duration of egg sensitization and the development of asthma

BACKGROUND: Egg sensitization, particularly persistent sensitization, is a risk factor for later asthma. However, little is known about accompanying IgG and subclass responses and how they might relate to asthmatic outcome. OBJECTIVE: To characterize hen's egg ovalbumin (OVA) IgG and subclass responses through the first 5 years of life in relation to duration of egg sensitization and later asthma. SUBJECTS and METHODS: The subjects (n=46) formed part of a larger cohort, born to atopic parents, who had been evaluated prospectively for the development of asthma. Egg sensitization was classified as transient (positive egg skin prick test at 1 year only) or persistent (positive skin test for at least 2 years). Plasma OVA IgG, IgG1 and IgG4 concentrations at birth (cord), 6 months, 1 and 5 years of age were measured by ELISA. RESULTS: The kinetics of OVA IgG and IgG1 responses, but not IgG4, differed between egg sensitized and non-egg sensitized (NES) children. Only persistently sensitized children had a rise in OVA IgG1 concentration through the first year of life, and at 1 year of age they had significantly higher OVA IgG and IgG1 than either transiently sensitized or NES children. High OVA IgG1 was associated with later asthma: at 1 year of age, OVA IgG1 greater than 14,500 U predicted asthma with a sensitivity 64% and specificity 74%. CONCLUSION: OVA IgG and subclass responses relate to the duration of egg sensitization. Measurement of OVA IgG1 concentration in infancy might offer a useful adjunct to identify those at an increased risk of asthma.