Specific Antibody Deficiency in Adult Patients With IgG or IgG Subclass Deficiency

PurposeSpecific antibody deficiency (SAD) involves a deficient response to a polysaccharide vaccine despite having normal immunoglobulin levels. The failure of the polysaccharide response can be observed as a component of various primary antibody deficiencies. However, only a few studies have described the clinical and immunological profiles in SAD and/or other primary immunodeficiencies (PIDs) in adults.MethodsA total of 47 patients who had a clinical history suggestive of antibody deficiency or had already been diagnosed with various antibody deficiencies were enrolled. Polysaccharide responses to 7 pneumococcal serotypes (4, 6B, 9V, 14, 18C, 19F and 23F) were measured using the World Health Organization enzyme-linked immunosorbent assay (WHO-ELISA), and postvaccination immunoglobulin G (IgG) titers were compared to clinical and laboratory parameters.ResultsBased on the American Academy of Allergy, Asthma, and Immunology (AAAAI) criteria for the WHO-ELISA, 11 (23.4%) patients were diagnosed as having SAD. Sixteen-three percent of them had combined with other types of PID, such as IgG subclass deficiency and hypogammaglobulinemia. Postvaccination IgG titers for the serotypes 4/9V/18C correlated with IgG2 (P = 0.012, P = 0.001, and P = 0.004) and for 6B/9V/14 with IgG3 (P = 0.003, P = 0.041, and P = 0.036, respectively). The IgG3 subclass levels negatively correlated with forced expiratory volume in 1 second (FEV1, %) and FEV1/forced vital capacity (P < 0.001 and P = 0.001, respectively).ConclusionSAD can be diagnosed in patients with normal IgG levels as well as in those deficient in IgG or the IgG3 subclass, implicating that restricted responses to Streptococcus pneumoniae polysaccharide antigens commonly exist in patients with predominantly antibody deficiency.     

IgG Subclass Antibody Response in Grass Pollen-Allergic Patients Undergoing Specific Immunotherapy

All four subclasses of IgG antibodies to timothy grass pollen extract were measured by a three-layer immunoradiometric assay in sera from 20 grass pollen-allergic patients who underwent specific immunotherapy in a 3-year prospective study. Both IgG1 and IgG4 antibody levels rose significantly during the first 8 weeks of immunotherapy. IgG1 antibody level passed its peak (median 5.4 U/ml) after 12 weeks. At this time, the ratio between the medians of IgG1 and IgG4 antibodies was 2.25. IgG4 antibody level reached its peak (median 11.6 U/ml) just before termination of immunotherapy. At this time IgG1/IgG4 ratio was 0.43. Two years after the end of immunotherapy, IgG1 and IgG4 antibody levels were 0.0 and 1.8 U/ml in median, respectively. The amounts of IgG2 and IgG3 antibodies detected in the sera were less than 1.6 U/ml and were considered insignificant. Preseasonal serum IgG1 and IgG4 antibody levels did not correlate significantly with symptom scores in the subsequent season. Serum IgG4 level obtained after 12 weeks of immunotherapy was significantly correlated to symptom score in the third season, i.e. the season just after termination of therapy (rs = 0.529, t = 2.567, P = 0.02). In this work, a serum IgG4 antibody level higher than 8.0 U/ml after 12 weeks of therapy predicted poor clinical result at the end of immunotherapy with 100% sensitivity and 87% specificity. An IgG4/IgG1 ratio greater than 1.0 after 12 weeks' therapy had the same predictive value.     

The Subclass Nature and Clinical Significance of the IgG Antibody Response in Patients Undergoing Allergen-Specific Immunotherapy

The purpose of this paper is to discuss the methodological difficulties in quantitation of human IgG subclass antibodies to allergens, to describe the subclass nature of the IgG antibody response in patients undergoing allergen-specific immunotherapy, and to discuss the possible immunological functions and clinical significance of allergen-specific IgG antibodies of different subclasses. Based on results obtained by use of assays with documented specificity it is concluded that the IgG antibody response during allergen-specific immunotherapy is IgG1 and IgG4 restricted, although low levels of IgG2 and IgG3 antibodies to some allergens may occur. In most patients the early IgG antibody response is IgG1 dominated and the late IgG4 dominated. A too early or too pronounced IgG4 dominated antibody response seems to indicate a poor clinical outcome of immunotherapy with inhalant allergens, whereas a pronounced early IgG1 antibody production has been found to be associated with a decrease in synthesis of IgE antibodies to an insect venom. It is therefore proposed that an early IgG1 dominated response is necessary to induce suppression of the ongoing IgE antibody production, which in its turn may be a prerequisite for long-lasting clinical effect. The possibility of induction of an early IgG1 dominated response in every patient by use of alternative immunotherapy procedures is discussed.     

Specific IgG Subclass Antibody Levels and Phagocytosis of Serotype 14 Pneumococcus Following Immunization

Complement and specific antibody directed against capsular polysaccharide are necessary for efficient phagocytosis of pneumococci. In normal adults, specific antibody to pneumococci is predominantly of the IgG2 subclass. However, the role of IgG2 in bacterial clearance is debatable. We therefore decided to investigate the relationship between specific IgG subclass antibody levels and phagocytosis of serotype 14 pneumococcus, before and after immunization with a pneumococcal capsular polysaccharide vaccine. Specific IgG subclass antibody was measured by an ELISA technique and the effect of serum on phagocytosis of radiolabelled pneumococci by normal polymorphs was determined. We found that in the presence of complement, phagocytosis correlated significantly with both specific IgGl and IgG2 antibody titres( r = 0.547, P = 0.002 and r = 0.464. P = 0.009, respectively). However, in decomplemented sera, the correlation with IgGl antibody was lost, whereas that with IgG2 antibody was strengthened ( r = 0.641. P = < 0.001). The possibility that IgG2 binds to receptors on polymorphs should be considered.     

The IgG Subclass Pattern of Complement Activation Depends on Epitope Density and Antibody and Complement Concentration

Using a matched series of human-mouse chimaeric IgG anti-5-iodo-4-hydroxy-3-nitrophenacetyl (anti-NIP) antibodies and NIP-bovine serum albumin (NIP-BSA) we examined how different variables influence the activation pattern of complement. When BSA was used with different hapten densities and the input of NIP-BSA was altered, we observed a change in the subclass reaction pattern. IgG3 fixed more Clq than IgG1 and IgG2 in all situations. IgG1 was slightly better than IgG3 and IgG2 at high antigen concentrations at activating C4 and C3 and inducing formation of the terminal complement complex (TCC). When the epitope density and/or the NIP-BSA concentration was reduced, IgG3 became best, followed by IgG1 and IgG2. IgG1 now revealed a marked prozone. Furthermore, IgG4 was found to activate C3 and mediate TCC formation at high epitope and complement concentrations.     

IgG Subclass Antibody Responses to Pneumococcal Polysaccharide Vaccine in Splenectomized, Otherwise Normal, Individuals

Subclasses of IgG antibodies to pneumococcal polysaccharide serotype antigens 4, 6A, and 23F were measured before and 4 weeks after vaccination with pneumococcal vaccine in young individuals splenectomized because of trauma and in a control group. An ELISA technique was applied. IgG2 anti-pneumococcal antibodies predominated before vaccination, especially against serotypes 4 and 6A. The youngest individuals in the splenectomy group tended to have lower IgG2 anti-pneumococcal antibody levels than the older ones. Vaccination induced antibodies of the IgG1 and IgG2 subclasses, and in some individuals also of the IgG4 subclass. Splenectomy does not seem to influence the IgG subclass pattern of antipneumococcal antibodies.     

A Three-Layer Immunoradiometric Assay for Determination of IgG Subclass Antibodies in Human Sera ("IgG Subclass RAST")

We report the development of a three-layer immunoradiometric assay (TIRA) for measurement of IgG antibodies of all four subclasses in human sera. The first layer consists of diluted human serum, the second layer is monoclonal mouse antibodies to human IgG subclasses., and the third layer is ¹²⁵I-labelled rabbit anti-mouse IgG. Monoclonal anti-IgG1. anti-IgC3 and anti-IgG4 reacted only with their complementary IgG subclass, whereas the anti-lgG2 showed slight cross-reactivity to immunoglobins of other subclasses and classes and to light chain proteins. The observed cross-reactivity was found to be without importance, when the TIRA was applied to measurement of IgG subclass antibodies. Equipotency was established by use of appropriate dilutions of the monoclonal antibodies, and the assay was calibrated by use of human reference serum. The TIRA therefore permits reliable inter-individual and intra-individual comparisons of the IgG antibody response in all four subclasses. Von-sped fie binding obtained with pooled normal human serum was below 0.33'#. Inter-assay coefficient of variation was between 18 and 27%, The TIRA was applied to measurement of IgG subclass antibodies to timothy grass pollen in sera from grass pollen allergies undergoing immunotherapy.     

Subclass Distribution of IgA and IgG Antibodies Against Clq in Patients with Rheumatic Diseases

To obtain insight into the immunoregulatory mechanisms in patients with different rheumatic diseases, the occurrence and the subclass distribution of IgA and IgG antibodies against Clq (anti-ClqAb) was determined. In patients with systemic lupus erythaematosus (SLE) the highest frequency of increased serum levels of IgG anti-ClqAb were found, whereas IgA anti-ClqAb were predominantly present in patients with ankylosing spondylitis (AS) and patients with rheumatoid arthritis complicated by vasculitis (RV). In all the IgA anti-ClqAb positive AS and RV patients the antibody reactivity involved the IgAl subclass while the IgA2 subclass was found in 47% of the patients. Further characterization of the IgA anti-Clq binding activity in sera of AS patients revealed that both subclasses of IgA anti-ClqAb were predominantly polymeric; the binding of both IgA subclasses with solid phase CI q was inhibitable by aggregated fluid phase Clq; we found no delectable interference of rheumatoid factor in the test system for the measurement of IgA anti-ClqAb. In patients with SLE the IgG anti-ClqAb reactivity was mainly of the IgG2 and IgG3 subclass, whereas in the same patients the IgG anti-tetanus toxoid response was not restricted to these subclasses.
The predominance of IgG2 and IgG3 subclass of anti-ClqAb in sera of SLE patients, suggests a skewing of the anti-ClqAb response. The observation that the IgA anti-ClqAb of both subclasses is predominantly polymeric in nature and the notion that polymeric IgA is associated with activation of inflammation cascades, suggests that IgA anti-ClqAb may contribute to tissue damage.     

Serum IgG and IgG Subclass Contents in Different Gm Phenotypes

Different serum IgG and IgG subclass levels were found among Gm phenotypes of a normal population. One hundred and fifty-seven Caucasian blood donors were investigated for the reciprocal Gm allotypes on IgG subclass loci namely: for IgG1, Glm(f) and Glm(a); for IgG2, G2m(n) and G2m("); and for IgG3, G3m(b) and G3m(g), and subgrouped in the seven most common Gm phenotypes. The frequencies of Gm phenotypes and haplotypes were given, including numbers of the previously little known G2m(n,") heterozygous individuals. Mean serum quantities ±SD and range of IgG, IgG1, IgG2, IgG3 and IgG4 were given for different Gm phenotypes. The IgG content was significantly lower in the Gm(f,",b/f,",b) phenotype in which the IgG2 levels were also significantly lower, compared with values of the other phenotypes. IgG3 levels were significantly lower in the Gm(a,",g/a,",g) phenotype compared with other phenotypes. These data imply the importance of Gm(f,",b/f,",b) and Gm(a,",g/a,",g) phenotypes causing lower amounts of IgG antibodies. In evaluating IgG subclass deficiency, the range for the low responding Gm(f,",b/f,",b) and Gm(a,",g/a,",g) phenotypes should be considered.     

IgM and IgG Subclass Distribution of Human Anti-Ro/SSA 60 kDa Autoantibodies

The Ro/SSA and La/SSB antigens are common targets for autoantibodies found in the sera of patients with Sjögren's syndrome and SLE. The anti-Ro/SSA and anti-La/SSB antibodies often appear together but are not cross-reactive. This paper describes the humoral autoimmune response to the Ro/SSA 60 kDa protein moiety with respect to the presence of IgM and IgG1-4 antibodies. IgM antibodies to the Ro 60 kDa protein coexisted with IgG anti-Ro 60 kDa antibodies in nearly half of the sera. A similar fraction also contained IgM anti-La/SSB antibodies. The frequency of sera with IgM antibodies of both specificities was that expected from random overlap.
A predominating igGl anti-Ro 60 kDa response was found in all patients, but anti-Ro 60 kDa antibodies of the other IgG subclasses were present also in a high number of sera. This is in contrast to the reported IgG subclass distribution of anti-La/SSB antibodies.
Mapping of IgM and IgG 1–4 antibody recognition of different parts of the Ro 60 kDa protein was also performed. IgM and IgGl-4 antibodies of all sera reacted with the central part of the Ro 60 kDa protein, encompassing amino acid residues 181–320.     

Subclass distribution of human IgG autoantibodies in pemphigus

The distribution of IgG subclasses in the intercellular substance (ICS) reactive autoantibodies in serum of 10 patients with pemphigus was analyzed by semiquantitative indirect immunofluorescence (IF) using the HP series of monoclonal antibodies specific for the four human IgG subclasses. IgG4 ICS specific autoantibody was present in all 10 sera at a titer of 10 to 320, while IgG1 antibodies were found in 9 of 10 sera at a seemingly lower level. IgG3 autoantibodies were detected in the serum of one patient, only after isolation of IgG using ion-exchange chromatography. Autoantibodies of IgG subclass 2 were not detectable in any of the 10 sera tested. One of the ten patients displayed circulating anti-ICS antibodies of only the IgG4 isotype.     

IgG Subclass Values from Normal Children in Cape Town

Sensitive and reproducible enzyme-linked immunoabsorbent assays (ELISA) have been developed to quantitate IgG subclass levels using monoclonal antibodies. Normal values for serum IgG subclass levels were determined in 300 healthy children between 6 months and 14 years of age and in SO adults. High levels of IgG 1 and delayed maturational development of IgG 2 in children from Cape Town are different to results reported from developed countries. Genetic differences may account for this.     

血清TGAb的测定在分化型甲状腺癌中的作用

探讨在电化学发光免疫法测定TG时TGAb对其测定的影响及TGAb在分化型甲状腺癌（DTC）患者中的阳性分布情况。在一高浓度的TGAb血清中加入一定量的高浓度TG（试剂R3）,测定TG的回收率,并对74例DTC患者在术前及术后一个月分别进行TG和TGAb的测定。结果显示,TGAb的浓度在2840.20～81.15IU/mL之间时,TG的回收率在73.99%～93.34%之间,TG的回收率同TGAb的浓度呈负相关（r=-0.9909,P〈0.01）;TGAb在DTC患者中的阳性率为29.7%,其中以乳头状癌伴桥本甲状腺炎组为最高（56.5%）。结论：在用电化学发光免疫法测定TG时TGAb会对其产生负干扰,并呈浓度依赖性,且TGAb在DTC患者中存在一定的阳性率,这应引起临床的重视,以防发生错误的临床诊断。     

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.     

Heterogeneity of Serum IgG Subclass Deficiencies in B Chronic Lymphocytic Leukemia

The occurrence of abnormally low serum immunoglobulin (Ig) levels is well-known in B chronic lymphocytic leukemia (CLL), but published data on IgG subclass levels are virtually absent. We measured serum IgG subclass levels in 52 B CLL outpatients, most in stage A and untreated, using an indirect immunoenzymatic assay with monoclonal antibodies. Mean levels of all Ig isotypes were lower than in normal controls in the whole group of patients, except for IgG2 in those studied at diagnosis. Levels of IgG1, IgG2, IgA, and IgM were lower in patients with a long disease duration than in those studied earlier. IgG subclass deficiencies occurred in 54% of cases and the most frequently affected isotype was IgG1. Every possible combination of IgG subclass and Ig class deficiencies from the selective deficiency of a single subclass to a combined deficiency of all isotypes was observed. This marked heterogeneity argues against the occurrence of isolated defects of one of the cytokines involved in Ig switching as a cause of hypoimmunoglobulinemia in CLL.     

In vitro Characterization of Synthesized Thyroglobulin Immune Complexes (IC)

Human thyroglobulin (Tg) immune complexes (TgIC) were preformed at different ratios from purified Tg, and Tg antibodies (TgAb) obtained from six patients with autoimmune thyroid diseases. TgIC were characterized by precipitation with polyethylene glycol, and sedimentation in sucrose gradient. TgIC from one patient were further characterized by concanavalin A (con A), and binding to the complement factor Clq and rheumatoid factor (RF).
Tg and TgIC had almost identical binding to con A, no binding to Clq, but could be partially separated by ultracentrifugation and polyethylene glycol. The highest degree of separation was obtained by a RF-coated plastic tube radiometric assay, using 125-I-rabbit TgAb as indicator. Tg showed no binding to RF, and a dose-response curve of TgIC in serum could be established. There was a dependence of the Tg-TgAb ratio, TgIC at equilibrium and in antibody excess being detected most efficiently.
The method may serve as an aid in the evaluation of the fate of Tg, TgAb and TgIC following thyroid damage (surgery, radioiodine) and may be extended as a model system in the investigation of immune complexes in connection with autoimmune disorders.     

Subclass Distribution of Human Anti-Staphylococcus aureus Alpha Toxin Antibodies: Suggestion of an IgG1, IgA1, IgG4 Switch Pattern

The subclass distribution of antibodies against alpha toxin from Staphylococcus aureus in man was investigated. Antibodies were restricted to IgG1, IgA1, and IgG4 and appeared to develop sequentially. These data suggest a distinct pattern of class and subclass switches in response to protein antigens. However, studies in immunodeficient (class- or subclass- deficient) donors show that the proposed patterns is not obligatory.     

Prevalence of IgG Anti-Der p 2 Antibodies in Children from High and Low Antigen Exposure Groups: Relationship of IgG and Subclass Antibody Responses to Exposure and Allergic Symptoms

Serum IgG PAN, IgG1-4, and IgE antibodies (Ab) specific for the house dust miteDermatophagoidesantigen (Ag) Der p 2 were measured by enzyme-linked immunosorbent assay (ELISA) in two groups of school children, age 12–14, exposed to high (Charlottesville, VA) and low (Los Alamos, NM) mite Ag levels in their environment. More than 90% of the children were found to have Der p 2-specific IgG antibodies, although the levels of both IgG PAN and IgG 1-4 Ab were substantially higher in the high exposure group (P= 0.001). In addition, there was considerable overlap between these two groups in all Ab measurements. The presence of IgG anti-Der p 2 Ab in the Los Alamos children was unexpected and suggests continuing Ag exposure, although the source of such exposure is not apparent. There is no correlation between RAST (+) and RAST (−) subjects with respect to the level of IgG Ab measured by ELISA. These results suggest that the IgG Ab response to house dust mite has been underestimated in the RAST negative population. Two twin pairs were included in this study and the divergent and varied Ab responses in these individuals indicate that factors in addition to environmental exposure and genetic susceptibility require further investigation and provide evidence for the complexity of the pathogenesis of the allergic response.     

Tg与TGA在分化型甲状腺癌术后监测及其疗效观察中的应用价值

目的：探讨甲状腺球蛋白（thyroglobulin,Tg）在分化型甲状腺癌（differentiated thyroid carcer,DTC）诊断及术后疗效观察中的应用价值。方法：采用放射免疫分析,对198例行甲状腺全切及次全切的DTC患者进行术后及术后半年血清Tg水平的追踪检测,同时行甲状腺球蛋白抗体（thyroglobulin antibody,TGA）的检测,并与正常对照组与转移组进行比较。结果：160例Tg〈20ng/ml的DTC患者阴性组术后1周血清Tg水平与对照组比较无明显差异（P〉0.05）;Tg水平〈10ng/ml者为56例,占35%。38例Tg〉20ng/ml阳性组术后1周时Tg水平明显高于阴性组和正常对照组（P〈0.01）。术后半年Tg水平随着病情好转逐渐下降,与术前1周之间呈明显正相关（t=4.951,P〈0.01）。23例远处转移癌的Tg水平明显高于颈部淋巴结转移组（P〈0.01）。术后Tg阴性患者其TGA增高者为25例,占20%。术后Tg阳性组TGA增高阳性率为42%。远处转移组TGA增高阳性率为56%。结论：Tg作为DTC的肿瘤标志物,在监测DTC手术效果、预后判断、复发、转移的诊断和鉴别治疗效果中具有重要的指导作用。