Allergen-specific IgE Antibodies Research Articles

Diagnostic Agreement of Different IgE Assay Methods, Immunocap and ‘Extended Range' Immulite 2000 3gAllergy in Japanese School Age Children

S U N D A Y 417 Diagnostic Agreement of Different IgE Assay Methods, Immunocap and Extended Range' Immulite 2000 3gAllergy in Japanese School Age Children Mari Kondo, Mayumi Sugimoto, MD, Keigo Kainuma, MD, Reiko Tokuda, Mizuho Nagao, MD, Takao Fujisawa, MD, FAAAAI; Mie National Hospital, Tsu, Japan, Mie National Hospital, Mie National Hospital, Mie, Japan. RATIONALE: Quantitative measures of allergen specific IgEantibody (sIgE) using different methods, IMMULITE 2000 3gAllergy (3g) and ImmunoCAP (CAP) assays, have to be interchangeable. Recently, extended measurement range of 3g, 0.1 ‘500IUA/mL, has been evaluated in Japan. METHODS: Serum samples were collected from 144 healthy and allergic children as classified by the ISAAC questionnaire. Samples were tested for total IgE (tIgE) and allergen specific IgE (sIgE) to house dust mite (HDM), Japanese cedar pollen (JCP), egg white and milk using both 3g and CAPassays. RESULTS: tIgE levels for CAP & 3g were almost identical.sIgE levels to various allergens by the two assays were highly correlated with Spearman’s r of >0.9. Values with the 3g assay tended to be higher than those by CAP, possibly a result of the wider 3greportable range. The area under the curve (AUC) determined from analysis of allergic and nonallergic groups were nearly identical between the assays for tIgE, sIgE for HDM and JCP, resulting in similar sensitivity and specificity calculations. Also in both methods, increasing sIgEto HDM correlated with a higher number of co-morbid allergic diseases. In particular, 3gshowed a greater significant difference because of the wider measurement range. CONCLUSIONS: sIgE levels to inhalant and food allergens measured by the 3g and CAP systems are highly correlated. The extended measurement range of the 3g assay may provide additional information for early detection of sensitization and monitoring of highly sensitized patients.

Evaluation of criteria for diagnosis of atopic dermatitis and detection of allergen specific IgE antibodies in dogs allergic to Ambrosia artemisiifolia pollen

Common ragweed (Ambrosia atremisiifolia) is one of the most frequent causes of pollen-induced allergic reactions both in humans and dogs. It has not been defined yet, what is the major allergen(s) to which most dogs allergic to ragweed show a positive result on intradermal skin test (IDST). In the present study sensitization to Ambrosia artemisiifolia pollen allergens in dogs with atopic dermatitis was examined with both in vivo and in vitro tests, including IDST and serum allergen specific IgE test. Detection of specific-IgE antibodies against ragweed allergens by immunoblotting in the sera of allergic dogs was optimized, as well. Dogs that were positive, as judged by IDST reactions to ragweed pollen allergens, also had alergen specific IgE antibodies in their sera. Results indicate that major allergens of A. artemisifolia pollen in dogs are Amb a 1 and Amb a 2. Further characterization of ragweed allergens is needed before they could potentially be used in intradermal testing or allergen immunotherapy in affected dogs. Also, we evaluated new Favrots diagnostic criteria for canine atopic dermatitis in dogs allergic to Ambrosia atremisiifolia pollen. It might be concluded that proposed criteria are of great assistance for seting up suspected diagnosis of canine atopic dermatitis, after ruling out other pruritic dermatoses. [Projekat Ministarstva nauke Republike Srbije, br. 172024]

Can Allergen-Specific IgE Antibodies Diagnose Egg Allergy Accurately?

Diagnosis of food allergy requires thorough history and physical examination, and/or skin prick tests or serum immunoassays to determine food-specific IgE (sIgE) antibodies for IgE-mediated food allergy.1 Double-blind placebo-controlled food challenges (DBPCFC) are actually still the gold standard for diagnosis.2 Many researchers endeavored to find solutions on diagnosing food allergies without food challenge tests. The traditional DBPCFC tests are time-consuming, expensive and troublesome for physician and patients. Serum immunoassays of food-sIgE has become a widely used modality to evaluate IgE-mediated food allergies.3 Higher concentrations of food-sIgE levels are correlated with an increasing likelihood of clinical allergic reactions but not generally associated with the severity.4-6 However, different predictive values are being suggested from recent studies, which might be influenced by diet, age, disease, and challenge protocol.5-7 Ethnicity or geographic location can also affect the difference in predictive values because they influence prevalence and causes of food allergies.8,9 Moreover, the absence of food-sIgE does not indicate absence of clinical reactions to food.10

Diagnosis of food allergies: the impact of oral food challenge testing

A diagnosis of food allergies should be made based on the observation of allergic symptoms following the intake of suspected foods and the presence of allergen-specific IgE antibodies. The oral food challenge (OFC) test is the most reliable clinical procedure for diagnosing food allergies. Specific IgE testing of allergen components as well as classical crude allergen extracts helps to make a more specific diagnosis of food allergies. The Japanese Society of Pediatric Allergy and Clinical Immunology issued the 'Japanese Pediatric Guideline for Food Allergy 2012' to provide information regarding the standardized diagnosis and management of food allergies. This review summarizes recent progress in the diagnosis of food allergies, focusing on the use of specific IgE tests and the OFC procedure in accordance with the Japanese guidelines.

False-positive penicillin immunoassay: An unnoticed common problem

False-positive penicillin immunoassay: An unnoticed common problem

The dynamics of soluble apoptosis markers during diet therapy in infants with atopic dermatitis

Background. To estimate the dynamics of soluble apoptosis markers in infants with atopic dermatitis for updating mechanisms of immunopathogenesis and improvement of diet therapy. Methods. We observed 66 bottle-fed infants aged 1,5—12 months old (boys -47, girls — 19) with atopic dermatitis (AD). The sensibilization to cow milk protein was revealed in all 66 infants. Detected allergen-specific IgG and IgE antibodies to cow milk protein, its fraction and goat milk protein were the reason to include infants into the 1st group and feed with hydrolyzed formula (27 infants). 39 infants in the 2nd group, who were not sensibilized to goat milk protein, were fed by goat milk based formula. Serum levels of soluble apoptosis markers (sCD153, caspase-8, sFas-L, caspase-9 and annexin-5) were measured by immunoenzyme method (ELISA). Results. The activation of signal apoptosis systems in infants with AD with increased levels of sFas-L и sCD153 was revealed. Levels of caspase-8 and caspase-9 were significantly lower than in control group, and reflected the impaired elimination of modified immmunocompetent cells. The level of annexin-5 was significantly lower in infants with AD than in control group. The estimation of the dynamics of investigated parameters during diet therapy showed significant increase of caspase-9 level in both groups. The level of caspase-8 was increased only in infants who were fed by goat milk formula. Levels of sFas-L, sCD153 and annexin-5 during diet treatment did not differ significantly between groups. Conclusion. The results showed that sCD153, caspase-8, sFas-L, caspase-9 and annexin-5 play a role in the realization of allergic inflammation in infants with AD. The diet therapy with goat milk formula promotes more physiological repair of the effectory component of the apoptosis.

Determination of allergen specificity by heavy chains in grass pollen allergen–specific IgE antibodies

Affinity and clonality of allergen-specific IgE antibodies are important determinants for the magnitude of IgE-mediated allergic inflammation. We sought to analyze the contribution of heavy and light chains of human allergen-specific IgE antibodies for allergen specificity and to test whether promiscuous pairing of heavy and light chains with different allergen specificity allows binding and might affect affinity. Ten IgE Fabs specific for 3 non-cross-reactive major timothy grass pollen allergens (Phl p 1, Phl p 2, and Phl p 5) obtained by means of combinatorial cloning from patients with grass pollen allergy were used to construct stable recombinant single chain variable fragments (ScFvs) representing the original Fabs and shuffled ScFvs in which heavy chains were recombined with light chains from IgE Fabs with specificity for other allergens by using the pCANTAB 5 E expression system. Possible ancestor genes for the heavy chain and light chain variable region-encoding genes were determined by using sequence comparison with the ImMunoGeneTics database, and their chromosomal locations were determined. Recombinant ScFvs were tested for allergen specificity and epitope recognition by means of direct and sandwich ELISA, and affinity by using surface plasmon resonance experiments. The shuffling experiments demonstrate that promiscuous pairing of heavy and light chains is possible and maintains allergen specificity, which is mainly determined by the heavy chains. ScFvs consisting of different heavy and light chains exhibited different affinities and even epitope specificity for the corresponding allergen. Our results indicate that allergen specificity of allergen-specific IgE is mainly determined by the heavy chains. Different heavy and light chain pairings in allergen-specific IgE antibodies affect affinity and epitope specificity and thus might influence clinical reactivity to allergens.

Passive immunization with allergen-specific IgG antibodies for treatment and prevention of allergy

IgE antibody-mediated allergies affect more than 25% of the population worldwide. To investigate therapeutic and preventive effects of passive immunization with allergen-specific IgG antibodies on allergy in mouse models we used clinically relevant pollen allergens. In a treatment model, mice were sensitized to the major birch pollen allergen Bet v 1 and to the major grass pollen allergens, Phl p 1 and Phl p 5 and then received passive immunization with rabbit IgG antibodies specific for the sensitizing or an unrelated allergen. In a prevention model, mice obtained passive immunization with allergen-specific rabbit IgG before sensitization. Kinetics of the levels of administered IgG antibodies, effects of administered allergen-specific IgG on allergen-specific IgE reactivity, the development of IgE and IgG responses and on immediate allergic reactions were studied by ELISA, rat basophil leukaemia degranulation assays and skin testing, respectively. Treated mice showed an approximately 80% reduction of allergen-specific IgE binding and basophil degranulation which was associated with the levels of administered allergen-specific IgG antibodies. Preventive administration of allergen-specific IgG antibodies suppressed the development of allergen-specific IgE and IgG1 antibody responses as well as allergen-induced basophil degranulation and skin reactivity. Our results show that passive immunization with allergen-specific IgG antibodies is effective for treatment and prevention of allergy to clinically important pollen allergens in a mouse model and thus may pave the road for the clinical application of allergen-specific antibodies in humans.

Establishing an allergic eczema model employing recombinant house dust mite allergens Der p 1 and Der p 2 in BALB/c mice

The major house dust mite allergens Der p 1 and Der p 2 are prevalent inducers of eczema. Der p 1 is a cysteine protease disrupting epithelial barriers, whereas Der p 2 functionally mimics the LPS-binding compound MD-2 within the TLR4 complex. In this work, we tested the percutaneous sensitizing capacity of recombinant (r) Der p 1 and Der p 2 in BALB/c mice. Mice were sensitized by percutaneous application of low (10 μg/application) and high dose (100 μg) rDer p 1 or rDer p 2, or with rDer p 1 followed by rDer p 2. Allergen-specific and total IgE antibodies were determined by ELISA. Eczema of BALB/c was classified by the itching score and corresponded to erosions. Infiltrating immune cells were identified by haematoxylin/eosin and Giemsa staining for eosinophils or mast cells, CD3 staining for T lymphocytes. Percutaneous treatments with rDer p 1, but not rDer p 2-induced specific IgG1. However, cotreatment with rDer p 1 led to increase in anti-Der p 2 IgG titres. Both allergens elicited skin erosions because of scratching, thickening of the epidermis, and eosinophil and T-cell infiltration. Our data indicate that recombinant mite allergens in the absence of adjuvant are sufficient for inducing eczema in BALB/c mice. As the enzymatic activity of an allergen might be an important cofactor for specific sensitization via the skin, Der p 1 may act as adjuvant for other allergens too. The presented mouse model is suitable for investigating the mechanisms of allergic eczema.

The majority of allergen‐specific IgE in the blood of allergic patients does not originate from blood‐derived B cells or plasma cells

The production of allergen-specific IgE antibodies is a hallmark of IgE-mediated allergy but the contribution of blood cells to allergen-specific IgE production in allergic patients has not been studied in detail. Aim of this study was the characterization of IgE-producing cells in the blood of allergic patients and the determination of the amount of IgE antibodies which are produced by these cells in relation to total amounts of circulating specific IgE. Peripheral blood mononuclear cells (PBMCs) were isolated from allergic patients and cell populations were purified or depleted using magnetically labelled antibodies directed against specific cell surface markers (CD19, CD20, CD22, CD27, CD38, CD126, CD138, CD203c). Allergen-specific IgE was measured in serum samples and cell culture supernatants by quantitative ImmunoCAP measurements and by ELISA using purified recombinant allergens. IgE transcripts were detected using RT-PCR with primers specific for human IgE. We found that allergen-specific IgE levels in PBMC supernatants correlated strongly with specific serum IgE but represented less than 1% of circulating IgE. Depletion of basophils resulted in substantial reduction of allergen-specific IgE levels in PBMC culture supernatants suggesting that an important source of allergen-specific IgE in PBMC supernatants could be IgE derived from the surface of basophils. Newly synthesized IgE was derived from CD138+ plasma cells, but not from B and B memory cells, and accounted for only approximately 0.2% of circulating IgE in blood. Our finding that the majority of allergen-specific IgE in the peripheral blood is not derived from IgE-secreting cells in the blood suggests local IgE production in tissues as a major source for allergen-specific IgE and possible target for therapeutic intervention.

Do all asthmatics with atopy have atopic asthma?

Do all asthmatics with atopy have atopic asthma?

Old questions and novel clues: Complexity of IgE repertoires

Old questions and novel clues: Complexity of IgE repertoires

Perinatal maternal administration of Lactobacillus paracasei NCC 2461 prevents allergic inflammation in a mouse model of birch pollen allergy.

BackgroundThe hygiene hypothesis implies that microbial agents including probiotic bacteria may modulate foetal/neonatal immune programming and hence offer effective strategies for primary allergy prevention; however their mechanisms of action are poorly understood. We investigated whether oral administration of Lactobacillus paracasei NCC 2461 to mothers during gestation/lactation can protect against airway inflammation in offspring in a mouse model of birch pollen allergy, and examined the immune mechanisms involved.MethodsBALB/c mice were treated daily with L. paracasei in drinking water or drinking water alone in the last week of gestation and during lactation. Their offspring were sensitized with recombinant Bet v 1, followed by aerosol challenge with birch pollen extract.ResultsMaternal exposure to L. paracasei prevented the development of airway inflammation in offspring, as demonstrated by attenuation of eosinophil influx in the lungs; reduction of IL-5 levels in bronchoalveolar lavage, and in lung and mediastinal lymph node cell cultures; and reduced peribronchial inflammatory infiltrate and mucus hypersecretion. While allergen-specific IgE and IgG antibody levels remained unchanged by the treatment, IL-4 and IL-5 production in spleen cell cultures were significantly reduced upon allergen stimulation in offspring of L. paracasei treated mice. Offspring of L. paracasei supplemented mothers had significantly reduced Bet v 1-specific as well as Concanavalin A-induced responses in spleen and mesenteric lymph node cell cultures, suggesting the modulation of both antigen-specific and mitogen-induced immune responses in offspring. These effects were associated with increased Foxp3 mRNA expression in the lungs and increased TGF-beta in serum.ConclusionOur data show that in a mouse model of birch pollen allergy, perinatal administration of L. paracasei NCC 2461 to pregnant/lactating mothers protects against the development of airway inflammation in offspring by activating regulatory pathways, likely through TLR2/4 signalling.

Allergische Transfusionsreaktionen bei einer Patientin mit multiplen Nahrungsmittelallergien

A 13-year-old girl with an osteosarcoma was treated by surgery and chemotherapy. During three transfusions of apheresis platelet concentrates allergic reactions occurred, partly in spite of premedication with an antihistamine and a corticoid. As the patient declared to be allergic to some foods, in-vitro tests for allergen-specific IgE antibodies were performed and showed markedly positive results for specific IgE to carrot and celery, less so to hazelnut, peanut and a lot of other food antigens. The donor of one of the unsuitable platelet concentrates remembered when questioned, that he had eaten carrots and chocolate with hazelnuts during the evening before platelet donation. Two washed platelet concentrates were transfused without any problem. Furthermore, transfusions of nine red blood cell concentrates and one unit of virus-inactivated frozen pooled plasma were well tolerated. Patients should be asked for allergies previous to transfusions to be alert to allergic reactions in patients with a positive history of food or drug allergies. If premedication with antihistamines does not prevent severe allergic transfusion reactions, transfusion of washed platelet concentrates and of virus-inactivated frozen pooled plasma can be considered.

Maternal Antibodies as an Immunotherapeutic Strategy in the Newborn

Studies using animal models have suggested several approaches for the prevention of allergen sensitization, such as the use of mutated allergens for vaccine engineering, schedules for oral tolerance induction, Treg induction and Th1 inducer adjuvants. Furthermore, experimental protocols involving the vaccination of the mother for indirect intervention in infants should be considered because initial allergen sensitization could occur during pregnancy or early infancy [6,7]. Maternal immunization is a particularly interesting approach for the passive transference of antibodies and other factors to the fetus/newborn as a regulatory mechanism for modulating the skewed Th2 neonatal immune responses of a Th2-linked allergy profile. In addition, maternal influences on the fetus or young infant are essential for the immunological decision between tolerance and immunity in the offspring. Several approaches attempting to induce maternal IgG allergen-specific antibodies have been shown to protect rat offspring against allergic sensitization [8,9], inhibiting anti-ovalbumin IgE antibody production for up to 14 weeks after birth. The efficiency of maternal immunization is associated with the period during which immunization occurs, and immunization during early gestation is more effective at controlling the allergic response of the offspring than immunization later in gestation [10]. The complete suppression of allergen-specific IgE antibodies in the offspring depends on the presence of maternal IgG 1 antibodies. We have shown that preconception immunization on mice with the dust mite Dermatophagoides pteronyssinus or ovalbumin promoted the transference of high levels of allergen-specific IgG antibodies via transplacental/amniotic pathways In recent decades, there has been an increase in the incidence of allergic disease worldwide, particularly in children. Several environmental stimuli and host genetic factors are involved in the development of allergies and viral infections in the neonatal period. There is evidence that prenatal risk factors, such as changes in diet during pregnancy or lactation, lifestyle and cigarette smoke, can interfere with epigenetics and lead to the early development of allergies [1]. Environmental agents implicated in airway disease can induce epigenetic changes that have important implications for the development of allergic and immunologic diseases. Risk factors that contribute to the development of atopy in newborns and children require prevention strategies that are initiated in early life. There is some evidence of a positive correlation between fetus sensitization and inhalant or food allergen exposure during pregnancy, as revealed in assays of antigen-specific cellular proliferation from the umbilical cords of children from atopic mothers [2,3]. However, studies of high-risk children have shown that the priming of Th2 responses associated with persistent IgE antibody expression against dust mites occurs entirely postnatally [4]. The timing of allergen sensitization is controversial, with conflicting evidence suggesting transplacental priming versus exclusively postnatal priming. Because the absolute avoidance of environmental allergens, even in the preor post-natal stage, is not possible, ongoing and future studies aim to generate mechanistic insights that will enable the rational design of vaccines and adjuvants for pregnant or nursing mothers or neonates and, thereby, reduce the incidence of allergy symptoms in infancy and early childhood [5].

The critical role of allergen-specific IgE, IgG4 and IgA antibodies in the tolerance of IgE-mediated food sensitisation in primary school children

Primary objective. There are about 6% of children who are either intolerant to or lose their ability to tolerate food allergens, resulting in the development of food hypersensitivity. The hypothesis that increase in food allergen-specific IgE antibody level is associated with the decrease in the levels of food allergen-specific IgG4 and IgA antibodies was used as a biomarker of food tolerance. Methods & Procedures. The Modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire (added gastrointestinal allergy questions) and Phadiatop infant test were used to screen one hundred 6–8-year-old allergic school children. Food allergen-specific IgE, IgG and IgA antibodies were measured by using the Phadia ImmunoCAP system radioabsorbent test (RAST). Immunoglobin E antibodies to common aeroallergens, were also detected by enzyme-linked immunosorbent assay. Main outcome. The level of analysed food specific-IgE antibody was obviously higher in the study population. Sensitivity to dust mites among the children was nearly 90%, and that to cockroach was 47%. Egg white-, cow's milk-, α-lactoalbumin-, β-lactoglobulin- and casein-specific IgG4/IgE and IgA/IgE ratios were lower in the atopic school children but not in the tropomysin-, mango- and kiwi-sensitive participants. Conclusion. The level of cow's milk- and egg white-specific IgE antibody still remained high along with a decrease in the specific IgG4/IgE and IgA/IgE ratios in our study population. Therefore, allergen-specific IgG4 and IgA antibodies are important biomarkers of tolerance establishment, and failure to establish tolerance to food allergens may be related to the regulation of the inhalant allergens encountered in late childhood stages.

Essential role of macrophages in the initiation of allergic rhinitis in mice sensitized intranasally once with cedar pollen: regulation of class switching of immunoglobulin in B cells by controlling interleukin-4 production in T cells of submandibular lym

The production of allergen-specific IgE antibodies (Abs) in allergen-sensitized patients or animals has a mutual relationship with the immunologic response leading to allergic rhinitis. We recently reported that, after an intranasal injection of cedar pollen into mice, an interleukin-4 (IL-4)-dependent increase in serum nonspecific IgE Abs was a prerequisite for the production of serum allergen-specific IgE Abs. Here, we explored which lymphoid organs were responsive to the intranasally injected allergen and how IL-4 and IgE Abs were produced in the lymphocytes. Time-dependent changes in the total cell numbers and in in vitro IgE Ab production in various lymphoid organs revealed that the submandibular lymph nodes were the main responsible organ. After treatment with allergen (for IgE production) or allergen and complete Freund's adjuvant (for IgG production), we separated submandibular lymph node cells into macrophage-, lymphocyte-, and granulocyte-rich populations by discontinuous Percoll density-gradient centrifugation. Unexpectedly, bulk cells, but not the lymphocyte- or macrophage-rich populations, produced significant amounts of IL-4, IgE, and IgG; whereas production was restored by addition of Mac-1(+) cells from the macrophage-rich to the lymphocyte-rich fraction. Furthermore, a combination of the lymphocyte-rich population (for IgG [or IgE]) production) and the macrophage-rich population (for IgE [or IgG]) production) produced a large amount of IgE (or IgG). These results indicate that, in the initiation of allergic rhinitis, macrophages in the submandibular lymph nodes are essential not only for IL-4 or immunoglobulin production, but also for class switching of immunoglobulin in lymphocytes.

Total IgE and allergen-specific IgE and IgG antibody levels in sera of atopic dermatitis affected and non-affected Labrador- and Golden retrievers

Canine atopic dermatitis (CAD) is an allergic skin disease associated with IgE and IgG antibodies (Ab) to environmental allergens. The aim of this study was to determine which other factors influence serum Ab levels in CAD-affected and non-affected dogs as this has only been poorly investigated in dogs so far.Total and allergen-specific IgE levels and Dermatophagoides farinae (DF)-specific IgG1 and IgG4 were measured by ELISA in sera of 145 CAD-affected and 271 non-affected Labrador- and Golden retrievers. A multivariable logistic regression analysis including the factors age, breed, gender, castration, clinical CAD status and allergen-specific immunotherapy (ASIT) was performed.Golden retrievers had more frequently total (OR=1.87, 95% CI=1.26–2.87, p<0.01) and specific IgE levels above the threshold value than Labrador retrievers, suggesting that genetic factors influence IgE levels in dogs. Castration was generally associated with low Ab levels (OR=0.43–0.65, p<0.05). Surprisingly, dogs with CAD did not have increased odds for high IgE against any of the allergens tested. ASIT with DF was associated with high DF-specific IgG1 (OR=4.32, 95% CI 1.46–12.8, p<0.01) but was not associated with DF-specific IgG4 or decreased IgE levels.Further studies are needed to understand the role of allergen-specific IgE in CAD and of IgG1 in ASIT.

High titers of IgE antibody to dust mite allergen and risk for wheezing among asthmatic children infected with rhinovirus

BackgroundThe relevance of allergic sensitization, as judged by titers of serum IgE antibodies, to the risk of an asthma exacerbation caused by rhinovirus is unclear.ObjectiveWe sought to examine the prevalence of rhinovirus infections in relation to the atopic status of children treated for wheezing in Costa Rica, a country with an increased asthma burden.MethodsThe children enrolled (n = 287) were 7 through 12 years old. They included 96 with acute wheezing, 65 with stable asthma, and 126 nonasthmatic control subjects. PCR methods, including gene sequencing to identify rhinovirus strains, were used to identify viral pathogens in nasal washes. Results were examined in relation to wheezing, IgE, allergen-specific IgE antibody, and fraction of exhaled nitric oxide levels.ResultsSixty-four percent of wheezing children compared with 13% of children with stable asthma and 13% of nonasthmatic control subjects had positive test results for rhinovirus (P < .001 for both comparisons). Among wheezing subjects, 75% of the rhinoviruses detected were group C strains. High titers of IgE antibodies to dust mite allergen (especially Dermatophagoides species) were common and correlated significantly with total IgE and fraction of exhaled nitric oxide levels. The greatest risk for wheezing was observed among children with titers of IgE antibodies to dust mite of 17.5 IU/mL or greater who tested positive for rhinovirus (odds ratio for wheezing, 31.5; 95% CI, 8.3-108; P < .001).ConclusionsHigh titers of IgE antibody to dust mite allergen were common and significantly increased the risk for acute wheezing provoked by rhinovirus among asthmatic children.

Chapter 31: Common in vitro tests for allergy and immunology

Allergen-specific IgE antibody is the most commonly ordered in vitro test in the practice of allergy and is used to diagnose type I hypersensitivity reactions to foods or reactivity to aeroallergens in patients with relative contraindications to skin-prick testing such as dermatographism. The Phadebas radioallergosorbent test (RAST; Pharmacia, Uppsala, Sweden) was the first assay reported for the detection of the allergen-specific IgE antibody. In a RAST, antigen (allergen) is bound to a solid phase, such as a paper disk, and then incubated with human serum. A buffer wash removes unbound serum proteins, and radiolabeled anti-human IgE is added to detect bound IgE, if present. The results are reported in arbitrary units of IgE per milliliter of serum. The term RAST was originally a brand name but it is now often used colloquially (and incorrectly) to describe any in vitro assay for allergen-specific IgE. Total serum IgE can be measured and is helpful in determining atopic presentations such as in allergic bronchopulmonary aspergillosis or in patients with persistent asthma who are candidates for monoclonal anti-IgE antibody therapy with, omalizumab. In patients with recurrent bacterial infections of the sinopulmonary tract, the basic humoral immune system testing includes measuring quantitative immunoglobulins (IgG, IgA, and IgM) and comparing them to age-matched normal ranges. Most clinical laboratories use nephelometry to measure immunoglobulin levels quantitatively. Nephelometry detects either the rate or the end point of soluble immune complex formation (the IgG in sera complexes with an anti-IgG antibody forming a classic immunoprecipitation reaction) by monitoring the scatter of transmitted light. The most common method for the screening of cellular immunodeficiency involved the measurement of the absolute and relative representation of the major lymphocyte subsets, T-cells, T-helper cells, T-cytotoxic cells, B-cells and NK-cells.