IgE Reactivity Research Articles

Cockroach allergen component analysis of children with or without asthma and rhinitis in an inner-city birth cohort

Cockroach is one of the most important sources of indoor allergens and can lead to IgE sensitization and development of rhinitis and asthma. We sought to perform a cockroach allergen component analysis to determine the allergens and antibody levels and patterns of sensitization associated with asthma and rhinitis. Antibody (IgE, IgG, and IgG4) levels to total cockroach and 8 cockroach allergens were determined in 2 groups of cockroach-sensitized 10-year-old children with (n=19) or without (n=28) asthma and rhinitis. Allergen-specific antibody levels were measured in streptavidin ImmunoCAPs loaded with each of the recombinant allergens from groups 1, 2, 4, 5, 6, 7, 9, and 11, and total cockroach-specific IgE levels were measured with the i6 ImmunoCAP. IgE antibody levels to cockroach allergens and extract, but not IgG or IgG4 antibody levels, differed between subjects with and without asthma and rhinitis. Specifically, recognition of more cockroach allergens with higher allergen-specific IgE levels was associated with disease. Variable patterns of sensitization with no immunodominant allergens were found in both groups. There was a good correlation between the sum of allergen-specific IgE and total cockroach IgE levels (r=0.86, P<.001). Component analysis of 8 cockroach allergens revealed significant differences in IgE reactivity associated with the presence of asthma and rhinitis. Allergen-specific IgE titers and sensitization profiles were associated with asthma and rhinitis.

The Prevalence of Food Allergy in Young Israeli Adults

Information regarding the prevalence of food allergy (FA) among adults is limited due to their inaccessibility for thorough epidemiological evaluations. To evaluate the prevalence of FA among Israeli young adults. All recruits (n= 12,592, ages 17-18 years) signing up over 6 months at a single recruitment center of the Israeli army were evaluated for FA. The evaluation included a frontal interview by physicians who used a focused screening set of questions, medical documentation collection, tests of IgE reactivity, and oral food challenges. The latter were performed at an allergy care institute in ambiguous cases. A prediction model for the identification of individuals with true allergy among recruits eliminating foods due to suspected FA was developed using multivariable logistic regression. Foods elimination due to suspected FA was reported by 148 recruits (1.2%). After diagnostic testing, FA was confirmed in 0.67% (84 of 12,592). The prevalence of food elimination versus diagnosed allergy was 0.2%/0.16% milk, 0.2%/0.14% peanuts, 0.13%/0.09% fish, 0.1%/0.09% sesame, 0.04%/0.015% egg, and 0.36%/0.28% tree nuts, respectively. On multivariable logistic regression analysis, male gender (adjusted odds ratio [OR]= 3.2, 95% confidence interval [CI]: 1.4-7.7), report of a common food allergen (OR= 3.6, 95% CI: 1.4-9.3), previous allergist evaluation for FA (OR= 7.8, 95% CI: 3-20.2), and FA reactions within the past 2 years (OR= 2.8, 95% CI: 1.2-6.7) were significantly identified as independent predictors of true FA. The prevalence of FA among Israeli young adults is lower than reported for other western countries. Reliance on food elimination alone does not accurately rule in FA. The use of the identified predictors for FA can facilitate large-scale epidemiological studies in adults.

Efficacy and Safety of Sesame Oral Immunotherapy—A Real-World, Single-Center Study

The presence of sesame in Western diet is increasing, making its avoidance by sesame-allergic patients more challenging. To report the efficacy and safety of sesame oral immunotherapy (OIT). Sixty patients aged 4 years or older, diagnosed as sesame-allergic on the basis of a positive oral food challenge, were consecutively enrolled into OIT between November 2014 and November 2017. Fifteen patients with sesame allergy, based on a positive oral food challenge or a recent immediate reaction, and a positive skin prick test result or specific IgE, continued sesame elimination and served as observational controls. Immunologic parameters were measured in a subset (OIT, n= 16; controls, n= 11) at the start and end of the study. Fully desensitized patients continued daily consumption of 1200 mg sesame protein and challenged with 4000 mg after more than 6 months. Fifty-three OIT-treated patients (88.4%) were fully desensitized to sesame, compared with 0% of controls. Four additional patients (total 57 of 60= 95%) were desensitized to more than 1000 mg protein. Reactions occurred in 4.7% of hospital doses and 1.9% of home doses. Epinephrine-treated reactions occurred in 16.7% of patients for hospital and 8.3% for home doses. Significant decreases in rSes i 1 IgE (P= .007) and basophil reactivity (P= .001) and increases in sesame and rSes i 1 IgG4 (P= .001) occurred in OIT-treated patients but not in controls. Forty-seven patients desensitized to 4000 mg were evaluated more than 6 months after reaching maintenance. Only mild reactions were reported during maintenance, and all passed the 4000-mg challenge. Sesame-OIT is an effective alternative to sesame avoidance in allergic patients. The potential for adverse events necessitates its performance in specialized centers.

Rational design of a hypoallergenic Phl p 7 variant for immunotherapy of polcalcin-sensitized patients

Polcalcins are important respiratory panallergens, whose IgE-binding capacity depends on the presence of calcium. Since specific immunotherapy is not yet available for the treatment of polcalcin-sensitized patients, we aimed to develop a molecule for efficient and safe immunotherapy. We generated a hypoallergenic variant of the grass pollen polcalcin Phl p 7 by introducing specific point mutations into the allergen’s calcium-binding regions. We thereby followed a mutation strategy that had previously resulted in a hypoallergenic mutant of a calcium-binding food allergen, the major fish allergen parvalbumin. Dot blot assays performed with sera from Phl p 7-sensitized patients showed a drastically reduced IgE reactivity of the Phl p 7 mutant in comparison to wildtype Phl p 7, and basophil activation assays indicated a significantly reduced allergenic activity. Rabbit IgG directed against mutant rPhl p 7 blocked patients’ IgE binding to wildtype Phl p 7, indicating the mutant’s potential applicability for immunotherapy. Mass spectrometry and circular dichroism experiments showed that the mutant had lost the calcium-binding capacity, but still represented a folded protein. In silico analyses revealed that the hypoallergenicity might be due to fewer negative charges on the molecule’s surface and an increased molecular flexibility. We thus generated a hypoallergenic Phl p 7 variant that could be used for immunotherapy of polcalcin-sensitized individuals.

Discovery of Alpha-Gal-Containing Antigens in North American Tick Species Believed to Induce Red Meat Allergy.

Development of specific IgE antibodies to the oligosaccharide galactose-α-1, 3-galactose (α-gal) following tick bites has been shown to be the source of red meat allergy. In this study, we investigated the presence of α-gal in four tick species: the lone-star tick (Amblyomma americanum), the Gulf-Coast tick (Amblyomma maculatum), the American dog tick (Dermacentor variabilis), and the black-legged tick (Ixodes scapularis) by using a combination of immunoproteomic approach and, carbohydrate analysis. Anti-α-gal antibodies identified α-gal in the salivary glands of both Am. americanum and Ix. scapularis, while Am. maculatum and De. variabilis appeared to lack the carbohydrate. PNGase F treatment confirmed the deglycosylation of N-linked α-gal-containing proteins in tick salivary glands. Immunolocalization of α-gal moieties to the salivary secretory vesicles of the salivary acini also confirmed the secretory nature of α-gal-containing antigens in ticks. Am. americanum ticks were fed on human blood (lacks α-gal) using a silicone membrane system to determine the source of the α-gal. N-linked glycan analysis revealed that Am. americanum and Ix. scapularis have α-gal in their saliva and salivary glands, but Am. maculatum contains no detectable quantity. Consistent with the glycan analysis, salivary samples from Am. americanum and Ix. scapularis stimulated activation of basophils primed with plasma from α-gal allergic subjects. Together, these data support the idea that bites from certain tick species may specifically create a risk for the development of α-gal-specific IgE and hypersensitivity reactions in humans. Alpha-Gal syndrome challenges the current food allergy paradigm and broadens opportunities for future research.

Analysis of allergen-specific T cell and IgE reactivity in milk and egg allergic children in response to progressive forms of baked milk and egg food extracts

Abstract Egg and milk allergy are among the most common food allergies in young children and are commonly outgrown. Developing tolerance is often clinically monitored by food challenge with cooked forms of egg and milk. This study characterizes IgE and T cell reactivity to four progressively cooked food extracts from egg and milk. Egg and milk-containing food extracts were prepared from most to least cooked foods: egg muffin, meat balls frittata and raw egg; milk muffin, pizza cheese, custard and raw milk. IgE reactivity against extracts was determined by western blot and protein-specific IgE reactivity was quantified. T cell reactivity against the extracts was determined by FluoroSpot (IL-5, IFNγ and IL-10) after 24h restimulation following a two week in vitro expansion culture. IgE reactivity varied between extracts, in a protein-specific manner. For milk, a protein band at 14 kDa corresponding in size to Bos d 4 is observed most strongly in raw milk and cheese extract, while being less reactive in custard and milk muffin. In contrast, a band at 67 kDa, corresponding to Bos d 6 in size, is most intense in milk muffin compared to raw milk, cheese and custard. For egg, trends are more consistent across the different proteins, with egg muffin showing most IgE reactivity throughout. Analysis of T cell responses showed highest IL-5 production for raw milk extract compared to custard (p=0.058), cheese (p=0.039) and muffin (p=0.097). No differences were observed for IFNγ and IL-10. For egg, no differences between extract-induced T cell reactivity was observed. Both IgE and T cell reactivity is readily detectable against food extracts from baked forms of egg and milk. Immunological reactivity is not necessarily associated with the degree of cooking.

Variability of allergens in commercial fish extracts for skin prick testing.

Commercial allergen extracts for allergy skin prick testing (SPT) are widely used for diagnosing fish allergy. However, there is currently no regulatory requirement for standardization of protein and allergen content, potentially impacting the diagnostic reliability of SPTs. We therefore sought to analyse commercial fish extracts for the presence and concentration of fish proteins and invitro IgE reactivity using serum from fish-allergic patients. Twenty-six commercial fish extracts from five different manufacturers were examined. The protein concentrations were determined, protein compositions analysed by mass spectrometry, followed by SDS-PAGE and subsequent immunoblotting with antibodies detecting4 fish allergens (parvalbumin, tropomyosin, aldolase and collagen). IgE-reactive proteins were identified using serum from 16 children with confirmed IgE-mediated fish allergy, with focus on cod, tuna and salmon extracts. The total protein, allergen concentration and IgE reactivity of the commercial extracts varied over 10-fold between different manufacturers and fish species. The major fish allergen parvalbumin was not detected by immunoblotting in 6/26 extracts. In 7/12 extracts, five known fish allergens were detected by mass spectrometry. For cod and tuna, almost 70% of patients demonstrated the strongest IgE reactivity to collagen, tropomyosin, aldolase A or β-enolase but not parvalbumin. Commercial fish extracts often contain insufficient amounts of important allergens including parvalbumin and collagen, resulting in low IgE reactivity. A comprehensive proteomic approach for the evaluation of SPT extracts for their utility in allergy diagnostics is presented. There is an urgent need for standardized allergen extracts, which will improve the diagnosis and management of fish allergy.

Isoforms of Group 1 Allergens from a Tropical/Subtropical Para Grass (Urochloa mutica) Display Different Levels of IgE Reactivity and Cross-reactivity.

Group 1 grass pollen allergens, or beta-expansins, are the most important major allergens from tropical/subtropical grasses. This study aimed to investigate the sequence similarity, and immunoreactivity of group 1 allergens from Para grass (Urochloa mutica). Three isoforms (Uro m 1.01, Uro m 1.02, and Uro m 1.03) were cloned from cDNA of Para grass pollen. The acidic-neutral isoforms rUro m 1.01 and rUro m 1.02 could effectively inhibited beta-expansins in pollen extract of Bermuda and Johnson grasses, suggesting that these isoforms could be major cross-reacting allergens among these grasses. In contrast, the basic isoform rUro m 1.03 had limited IgE reactivity. Thus, group 1 allergens both acidic-neutral and basic isoforms could have markedly different IgE reactivity.

Multiplexed immunoassay approach to characterize antidrug antibody like specific reactivity.

Aim: Characterization of antidrug antibody (ADA)-like reactivity has emerged as critical element of bioanalytical design and assessment of compound immunogenicity risk. Materials& methods: Multiplex immunoassay was applied to detect and characterize ADA like reactivity using Photonic Ring Immunoassay platform (Genalyte). Specific binding to human IgE or human recombinant IL21-receptor-Fc fusion using exogenous reagents as surrogates for drug-specific reactivity was investigated. Results: Multiplexed assay format allowed identification of spiked antihuman IgE reactivity as murine IgG1 and endogenous antihuman recombinant IL21-receptor-Fc reactivity in rheumatoid arthritis sera as antihuman Fc-specific binding. Conclusion:The ability of a multiplex immunoassay platform to identify isotype and domain specificity of antidrug immunoglobulins was shown to be effective and should be considered when screening and characterizing pre- and post-dose ADA reactivity.

Fusion proteins consisting of Bet v 1 and Phl p 5 form IgE-reactive aggregates with reduced allergenic activity

The cross-linking of effector cell-bound IgE antibodies by allergens induces the release of inflammatory mediators which are responsible for the symptoms of allergy. We demonstrate that a recombinant hybrid molecule consisting of the major birch (Bet v 1) and grass (Phl p 5) pollen allergen exhibited reduced allergenic activity as compared to equimolar mixes of the isolated allergens in basophil activation experiments. The reduced allergenic activity of the hybrid was not due to reduced IgE reactivity as demonstrated by IgE binding experiments using sera from allergic patients. Physicochemical characterization of the hybrid by size exclusion chromatography, dynamic light scattering, negative-stain electron microscopy and circular dichroism showed that the hybrid occurred as folded aggregate whereas the isolated allergens were folded monomeric proteins. IgG antibodies raised in rabbits against epitopes of Bet v 1 and Phl p 5 showed reduced reactivity with the hybrid compared to the monomeric allergens. Our results thus demonstrate that aggregation can induce changes in the conformation of allergens and lead to the reduction of allergenic activity. This is a new mechanism for reducing the allergenic activity of allergens which may be important for modifying allergens to exhibit reduced side effects when used for allergen-specific immunotherapy.

Microarray assessment of N-glycan-specific IgE and IgG profiles associated with Schistosoma mansoni infection in rural and urban Uganda

Core β-1,2-xylose and α-1,3-fucose are antigenic motifs on schistosome N-glycans, as well as prominent IgE targets on some plant and insect glycoproteins. To map the association of schistosome infection with responses to these motifs, we assessed plasma IgE and IgG reactivity using microarray technology among Ugandans from rural Schistosoma mansoni (Sm)-endemic islands (n = 209), and from proximate urban communities with lower Sm exposure (n = 62). IgE and IgG responses to core β-1,2-xylose and α-1,3-fucose modified N-glycans were higher in rural versus urban participants. Among rural participants, IgE and IgG to core β-1,2-xylose were positively associated with Sm infection and concentration peaks coincided with the infection intensity peak in early adolescence. Responses to core α-1,3-fucose were elevated regardless of Sm infection status and peaked before the infection peak. Among urban participants, Sm infection intensity was predominantly light and positively associated with responses to both motifs. Principal component and hierarchical cluster analysis reduced the data to a set of variables that captured core β-1,2-xylose- and α-1,3-fucose-specific responses, and confirmed associations with Sm and the rural environment. Responses to core β-1,2-xylose and α-1,3-fucose have distinctive relationships with Sm infection and intensity that should further be explored for associations with protective immunity, and cross-reactivity with other exposures.

Clinical and immunological differences between asymptomatic HDM-sensitized and HDM-allergic rhinitis patients.

Confirmation of the clinical relevance of sensitisation is important for the diagnosis of allergic rhinitis. To investigate the usefulness of an in vitro basophil activation test and component-resolved diagnosis in distinguishing between symptomatic allergic rhinitis patients and asymptomatic sensitization to house dust mites (HDMs). Thirty-six subjects with a positive skin prick test (SPT) for HDM were divided into a symptomatic (n=17) and an asymptomatic (n=19) group on the basis of their clinical history and a nasal provocation test. A basophil CD63 response to in vitro stimulation with Dermatophagoidespteronyssinus whole allergen extract and the IgE reactivity profiles for Der p 1, 2, 4, 5, 7, 10, 11, 14, 15, 18, 21, 23 were evaluated. Serum IgE and IgG specific to Dpteronyssinus whole allergen extract and total IgE were measured. There were no statistically significant differences in the levels of IgE (IgE levels were higher in symptomatic patients with P=0.055) and IgG specific to Dpteronyssinus and total IgE. Symptomatic patients showed a lower threshold for in vitro basophil activation (3.33ng/mL vs 33.3ng/mL), a higher area under the curve (AUC) of basophil activation (171 vs 127) (P=0.017), a higher response to positive control with anti-FcεRI stimulation (97% vs 79%) (P<0.001), a recognition of more HDM allergens (4 vs 2) and more frequent sensitization to rDer p 7 (P=0.016) and rDer p 23 compared to asymptomatic subjects (P=0.018). There was a positive correlation (r=0.63; P<0.001) between the number of recognized allergens and the AUC of basophil activation. In the subjects studied, the differences in the basophil response to Dpteronyssinus allergen extract, number of recognized HDM allergens and reactivity to rDer p 7 and rDer p 23 distinguish symptomatic from asymptomatic HDM sensitisation better than SPT or allergen extract-specific IgE. Information regarding the clinical relevance of sensitization is important for the prescription of allergen-specific immunotherapy.

Impact of lipid binding on the tertiary structure and allergenic potential of Jug r 3, the non-specific lipid transfer protein from walnut

Plant non-specific lipid transfer proteins type 1 (nsLTP1) are small basic proteins with a hydrophobic cavity able to host a number of different ligands: i.e. fatty acids, fatty acyl-CoA, phospholipids, glycolipids, and hydroxylated fatty acids. However, ligand binding specificity differs among nsLTPs. Within this protein family, Jug r 3 from walnut has been identified as a major allergen. So far, data on the structural characterization of Jug r 3 and its lipid binding capacity are lacking. We report the results from a fluorescence-based ligand-binding assay and ligand-based NMR experiments, to study the binding interactions between Jug r 3 and the 18-carbon monounsaturated oleic acid. Furthermore, protein-based NMR experiments were employed to detect the oleate binding site of Jug r 3. The NMR data were used to dock the oleate molecule into the structural model of Jug r 3. Finally, the impact of the interaction on the allergenic potential of Jug r 3 was investigated by IgE ELISA with 6 sera from walnut allergic patients. Our data corroborate the hypothesis of direct impact of food-derived matrix on the IgE reactivity of nsLTPs.

Crystal structure of the dog allergen Can f 6 and structure-based implications of its cross-reactivity with the cat allergen Fel d 4

Several dog allergens cause allergic reactions in humans worldwide. Seven distinct dog allergens, designated Canis familiaris allergen 1 to 7 (Can f 1–Can f 7), have been identified thus far. Can f 6 shows high sequence similarity and cross-reactivity with Fel d 4 and Equ c 1, major cat and horse allergens, respectively. This study was conducted on the allergenic epitopes of Can f 6 based on its structural characterization. We demonstrated that sera from 18 out of 38 (47%) dog-sensitized patients reacted to recombinant Can f 6 protein (rCan f 6). We then determined the crystal structure of rCan f 6 by X-ray crystallography, which exhibited a conserved tertiary structural architecture found in lipocalin family proteins. Based on the tertiary structure and sequence similarities with Fel d 4 and Equ c 1, we predicted three IgE-recognizing sites that are possibly involved in cross-reactivity. Substituting three successive amino acids in these sites to triple alanine decreased IgE reactivity to the allergen. However, the degree of reduction in IgE reactivity largely depended on the site mutated and the serum used, suggesting that Can f 6 is a polyvalent allergen containing multiple epitopes and Can f 6-reactive sera contain varied amounts of IgE recognising individual Can f 6 epitopes including those predicted in this study. We also demonstrated that the predicted epitopes are partly involved in IgE cross-reactivity to Fel d 4. Interestingly, the effect of the mutation depended on whether the protein was structured or denatured, indicating that the bona fide tertiary structure of Can f 6 is essential in determining its IgE epitopes.

New Insights of Biomarkers in IgE and Non-IgE-Mediated Drug Hypersensitivity

Background Drug hypersensitivity reactions (DHRs) occurring less than 6 h after the drug intake are named immediate reactions. They include allergic reactions, and pseudo-allergic or non-allergic reactions, and despite their similar clinical manifestations, the underlying mechanism is different. Its identification is essential for their management. In IgE-mediated-DHRs, the best biomarker is drug-specific IgE, which can be determined by in vivo and in vitro tests. Identifying the culprit drug is critical for the design of avoidance strategies and the recommendation of safe alternatives for future treatments. Recent findings It has been suggested the existence of other mechanisms beyond IgE and related with the drug interaction with MRGPRX2 or IgG receptors, or mediated by their effect on some enzymes. However, the lack of a clear biomarker for characterizing them, together with the difficulty of predicting cross-reactivity, makes the management of non-allergic reactions very complex. Desensitization is standard intervention in allergic patients who need the drug. It is successful in IgE-mediated DHRs but its value on non-IgE-mediated DHRs is not well-known. Summary Further research is needed to identify the mechanism involved in DHRs considering that IgE and non-allergic reactions cannot be mutually exclusive and can happen simultaneously, increasing their severity. It is crucial the identification of biomarkers in non-allergic reactions.

Molecular IgE reactivity pattern in Lipid Transfer Protein (LTP) allergy using a new multiplex diagnostic array.

Molecular IgE reactivity pattern in Lipid Transfer Protein (LTP) allergy using a new multiplex diagnostic array.

IgE reactivity to Pacific cod (Gadus macrocephalus) fish allergens in dogs with canine atopic dermatitis

IgE reactivity to Pacific cod (Gadus macrocephalus) fish allergens in dogs with canine atopic dermatitis

Modulation of Allergic Reactivity in Humans Is Dependent on Schistosoma mansoni Parasite Burden, Low Levels of IL-33 or TNF-α and High Levels of IL-10 in Serum.

Helminth infections and allergies are characterized by a predominant type-2 immune response. In schistosomiasis, the Th-2 response is usually accompanied by induction of immunoregulatory mechanisms that contribute to worm survival and less severe schistosomiasis. Although helminth-induced immunomodulatory mechanisms seem to affect atopy, epidemiological studies on the relationship between helminths and allergy have been inconsistent, and data suggest that the modulatory effects may be influenced by helminth species, chronicity of infection, and parasite burden. Here we performed a cross-sectional study to investigate the effects of Schistosoma mansoni parasite burden and immune response on allergic reactivity of individuals living in a schistosomiasis endemic area in Brazil. Fecal samples from the participants were collected for extensive parasitological examinations by spontaneous sedimentation, Kato-Katz, Helmintex and Saline Gradient tests and molecular detection of S. mansoni by qPCR. Additionally, the concentrations of cytokines and chemokines, total IgE and IgE-reactivity to common house dust allergens were quantified from serum samples. IgE reactivity to dust allergens was detected in 47 individuals (23.8%), and 140 individuals (54.4%) were diagnosed with S. mansoni infection. Most of the infected population (108 individuals) presented very low parasite burden (≤12 eggs/g of feces). The frequency and intensity (p ≤ 0.03) of allergic reactivity were lower in S. mansoni-infected compared with non-infected individuals. Multivariable logistic regression models adjusted by age revealed that allergic reactivity was positively associated with low IL-10 response (OR, 4.55, 95% CI, 0.56–7.36) and high concentration of the inflammatory mediators IL-33 (OR, 2.70, 95% CI, 1.02–7.15) or TNF-α (OR, 6.88, 95% CI, 0.32–143.39) in serum, and inversely associated with S. mansoni infection (OR, 0.38, 95% CI, 0.16–0.87). Most importantly, the logistic regression demonstrated that the modulatory effects of Schistosoma infection depend on parasite burden, with individuals infected with ≤12 eggs/g of feces showing allergic IgE-reactivity similar to non-infected individuals Altogether, our data show that immunomodulation of allergic reactivity depends on S. mansoni burden, low type-2 inflammatory response, and high level of IL-10.

IgE testing can predict food allergy status in patients with moderate to severe atopic dermatitis

BackgroundDiagnosing food allergy in patients with atopic dermatitis (AD) is complicated by their high rate of asymptomatic sensitization to foods, which can lead to misdiagnosis and unnecessary food avoidance. ObjectiveWe sought to determine whether food-specific (sIgE) or component immunoglobulin (Ig) E levels could predict allergic status in patients with moderate to severe AD and elevated total IgE. MethodsSeventy-eight children (median age, 10.7 years) with moderate to severe AD were assessed for a history of clinical reactivity to milk, egg, peanut, wheat, and soy. The IgE levels for each food and its components were determined by ImmunoCAP. The level and pattern of IgE reactivity to each food and its components, and their ratio to total IgE, were compared between subjects who were allergic and tolerant to each food. ResultsNinety-one percent of subjects were sensitized, and 51% reported allergic reactivity to at least 1 of the 5 most common food allergens. Allergy to milk, egg, and peanut were most common, and IgE levels to each of these foods were significantly higher in the allergic group. Component IgEs most associated with milk, egg, and peanut allergy were Bos d8, Gal d1, and Ara h2, respectively. The ratio of sIgE to total IgE offered no advantage to sIgE alone in predicting allergy. ConclusionSpecific IgE levels and the pattern of IgE reactivity to food components can distinguish AD subjects allergic vs tolerant to the major food allergens and may therefore be helpful in guiding the clinical management of these patients.

Immunological characterization of the American cockroach allergen Per a 9 expressed in baculovirus-infected insect cells.

American cockroach (CR) allergy has been recognized as important IgE-mediated type I hypersensitivity. Per a 9 is an arginine kinase, reacting with IgE in sera of all CR allergic Thai patients. Per a 9 gene was cloned and expressed in eukaryotic systems (baculovirus-infected insect cells). The expressed Per a 9 was purified by Nickel column. The antigenicities were analyzed by ELISA, immunoblot analysis and basophile activation test. The results show that 13 out of 16 (81.3%) sera from American CR patients reacted to Per a 9, confirming that Per a 9 is a major allergen of CR. The IgE reactivity of Per a 9 in the sera from American CR patients was increased 8.3-fold in comparison with the sera from healthy controls. Per a 9 at 1.0 μg/ml induced an approximately up to 5.6-fold increase in CD63 and CCR3 double positive cells when incubating with passively sensitized basophils from by sera from American CR patients.