Allergenic Characterization of a Novel Allergen,Homologous to Chymotrypsin,from German Cockroach

Purpose

Cockroach feces are known to be rich in IgE-reactive components. Various protease allergens were identified by proteomic analysis of German cockroach fecal extract in a previous study. In this study, we characterized a novel allergen, a chymotrypsin-like serine protease.

Methods

A cDNA sequence homologous to chymotrypsin was obtained by analysis of German cockroach expressed sequence tag (EST) clones. The recombinant chymotrypsins from the German cockroach and house dust mite (Der f 6) were expressed in Escherichia coli using the pEXP5NT/TOPO vector system, and their allergenicity was investigated by ELISA.

Results

The deduced amino acid sequence of German cockroach chymotrypsin showed 32.7 to 43.1% identity with mite group 3 (trypsin) and group 6 (chymotrypsin) allergens. Sera from 8 of 28 German cockroach allergy subjects (28.6%) showed IgE binding to the recombinant protein. IgE binding to the recombinant cockroach chymotrypsin was inhibited by house dust mite chymotrypsin Der f 6, while it minimally inhibited the German cockroach whole body extract.

Conclusions

A novel allergen homologous to chymotrypsin was identified from the German cockroach and was cross-reactive with Der f 6.     

IgE Reactivity of the Dog Lipocalin Allergen Can f 4 and the Development of a Sandwich ELISA for Its Quantification

Purpose

Divergent results on the IgE reactivity of dog-allergic subjects to Can f 4 have been reported. The aim of this study was to evaluate the significance of Can f 4 in dog allergy and to develop an immunochemical method for measuring Can f 4 content in environmental samples.

Methods

We purified the natural dog allergen Can f 4 from a dog dander extract by monoclonal antibody-based affinity chromatography and generated its variant in a recombinant form. Sixty-three dog-allergic patients and 12 nonallergic control subjects were recruited in the study. The IgE-binding capacity of natural Can f 4 and its recombinant variant was assessed by ELISA, immunoblotting, and skin prick tests (SPT).

Results

Eighty-one percent of the dog-allergic patients showed a positive result to the immunoaffinity-purified natural Can f 4 in IgE ELISA, but only 46% in IgE immunoblotting. Respective results with the recombinant Can f 4 variant were 54% and 49%. SPT results reflected those obtained in ELISA and immunoblotting. The overall IgE reactivity of the immunoaffinity-purified natural Can f 4 was found to depend strongly on the integrity of the allergen''s conformation. A sandwich ELISA based on monoclonal antibodies was found to be functional for measuring Can f 4 in environmental samples.

Conclusions

Can f 4 is a major allergen of dog together with Can f 1 and Can f 5. In combination with other dog allergens, it improves the reliability of allergy tests in dog allergy.     

Specific B-cell Epitope of Per a 1: A Major Allergen of American Cockroach (Periplaneta americana) and Anatomical Localization

Purpose

Cockroach (CR) is a common source of indoor allergens, and Per a 1 is a major American CR (Periplaneta americana) allergen; however, several attributes of this protein remain unknown. This study identifies a novel specific B cell epitope and anatomical locations of Per a 1.0105.

Methods

Recombinant Per a 1.0105 (rPer a 1.0105) was used as BALB/c mouse immunogen for the production of monoclonal antibodies (MAb). The MAb specific B cell epitope was identified by determining phage mimotopic peptides and pair-wise alignment of the peptides with the rPer a 1.0105 amino acid sequence. Locations of the Per a 1.0105 in P. americana were investigated by immunohistochemical staining.

Results

The rPer a 1.0105 (~13 kDa) had 100%, 98% and ≥90% identity to Per a 1.0105, Per a 1.0101, and Cr-PII, respectively. The B-cell epitope of the Per a 1.0105 specific-MAb was located at residues⁹⁹ QDLLLQLRDKGV¹¹⁰ contained in all 5 Per a 1.01 isoforms and Per a 1.02. The epitope was analogous to the Bla g 1.02 epitope; however, this B-cell epitope was not an IgE inducer. Per a 1.0105 was found in the midgut and intestinal content of American CR but not in the other organs. The amount of the Per a 1 was ~544 ℃g per gram of feces.

Conclusions

The novel Per a 1 B-cell epitope described in this study is a useful target for allergen quantification in samples; however, the specific MAb can be used as an allergen detection reagent. The MAb based-affinity resin can be made for allergen purification, and the so-purified protein can serve as a standard and diagnostic allergen as well as a therapeutic vaccine component. The finding that the Per a 1 is contained in the midgut and feces is useful to increase yield and purity when preparing this allergen.     

IgE-binding epitopes of the American cockroach Per a 3 allergen

BACKGROUND: The Per a 3 is a species-specific allergen of the American cockroach (Periplaneta americana) related to insect hemolymph proteins and includes four known isoallergens. This study aimed to identify Per a 3 linear IgE-binding epitopes. METHODS: Per a 3 recombinant fragments were generated from the recombinant Per a 3.01 allergen (685 amino acid residues) by using existing restriction sites or by using polymerase chain reaction products, and expressed in Escherichia coli. Antigenicities were assessed by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and binding inhibition with human IgE. RESULTS: Human IgE recognized recombinant fragments 340-425, 466-579, 502-595, and 595-636 as revealed by immunoblotting and ELISA. On the other hand, the N-terminal fragment 1-399, recombinants 410-443, 472-551, 502-579, 606-636, and the C-terminal fragment 636-685 were unable to bind human IgE. Amino acid sequences 400-409, 466-471, 580-595, and 595-605 were shown to be required for IgE binding to the Per a 3.01 allergen, suggesting that the C-terminus contains most of the IgE-binding sites. Four peptides corresponding to these IgE-binding amino acid sequences were synthesized. These peptides reacted with most sera (62.5-87.5%) tested as revealed by ELISA, demonstrating a heterogeneous IgE-binding response. Moreover, preincubation of IgE-positive recombinant proteins and synthetic peptides with atopic IgE resulted in marked inhibition of the IgE binding to Per a 3.01 allergen. Amino acid sequences 400TVLRDPVFYQ409, 466NNVDQI471, 580VDKGHNYCGYPENLLI595, and 595IPKGKKGGQAY605 of the major recombinant American cockroach Per a 3.01 allergen were involved in IgE binding. CONCLUSION: These findings will advance our understanding of the antigenic structures responsible for allergenicity to the American cockroach, thereby providing strategies for the development of immunotherapies.     

Significance of 40-, 45-, and 48-kDa Proteins in the Moderate-to-Severe Clinical Symptoms of Buckwheat Allergy

Purpose

This study was aimed to investigate the relationship between the allergen components and moderate-to-severe allergic reactions in patients with buckwheat allergy.

Methods

Fifteen patients with a history of buckwheat ingestion and a buckwheat specific IgE level≥0.35 kU/L were enrolled. They were divided into 2 groups according to clinical severity scores, with 0-1 being asymptomatic-to-mild and 2-4 being moderate-to-severe symptoms. Immunoblotting was performed to investigate IgE reactivity toward buckwheat allergens and to measure intensity of each component by using a reflective densitometer.

Results

The proportions of positive band to the 16 kDa (62.5% vs 0%, P=0.026) and 40-50 kDa (87.5% vs 28.6%, P=0.041) buckwheat allergens in the grade 2-4 group were higher than those in grade 0-1 group. The level of buckwheat specific IgE of grade 2-4 group was higher than that of grade 0-1 group (41.3 kU/L vs 5.5 kU/L, P=0.037). The median optical densities (ODs) of IgE antibody binding to 40-50 kDa protein were higher in the grade 2-4 group, compared with those in the grade 0-1 group (130% OD vs 60.8% OD, P=0.037).

Conclusions

The 40-50 kDa protein is implicated as an important allergen to predict moderate-to-severe clinical symptoms in Korean children with buckwheat allergy.     

Profiles of IgE Sensitization to Der f 1, Der f 2, Der f 6, Der f 8, Der f 10, and Der f 20 in Korean House Dust Mite Allergy Patients

Purpose

Measurement of IgE specific to purified house dust mite (HDM) allergens may improve allergy diagnosis. This study aimed to investigate the sensitization profiles of Korean HDM allergic subjects suffering from respiratory allergy and atopic dermatitis (AD) to Der f 1, Der f 2, Der f 6, Der f 8, Der f 10, and Der f 20.

Methods

Recombinant HDM allergens were produced in Pichia pastoris (Der f 1) or Escherichia coli (5 allergens). IgE reactivity to the individual recombinant allergens and total extract of mite was assessed by ELISA.

Results

Der f 1 was recognized by 79.1%, Der f 2 by 79.1%, Der f 6 by 9.3%, Der f 8 by 6.2%, Der f 10 by 6.2%, and Der f 20 by 6.6% of the patients'' sera tested, while the prevalence of IgE reactivity to total mite extract was 94.7%. Combination of Der f 1 and Der f 2 had a sensitivity of 87.6%. Specific IgE to Der f 2 alone was detected from 89.4% of HDM-sensitized respiratory allergy subjects and 92.3% to the combination of the 2 major allergens Der f 1 and Der f 2. However, sera from fewer patients with AD, namely 72.4% and 71.0%, recognized Der f 1 and Der f 2, respectively. The combination of 2 major allergens allowed diagnosis of 84.5% of the AD patients. No correlation between sensitization to specific allergens and HDM allergy entity was found.

Conclusions

Der f 2 was the most frequently sensitized allergen among the HDM-sensitized respiratory and AD patients in Korea, and the combination of the group 1 and 2 major allergens increased the diagnostic sensitivity. Minor allergens did not significantly improve diagnostic sensitivity. However, further studies are needed to analyze the relationship between sensitization to other HDM allergens and the disease entity of the HDM allergy.     

Immunogenic peptides: B & T Cell Epitopes of Per a 10 Allergen of Periplaneta americana

Mapping of B and T cell epitopes of an allergen can be utilised in the development of alternative therapeutic modalities and diagnostics. The present study was aimed to identify B and T cell epitopes of Per a 10, a major cockroach allergen, by computational tools and subsequent validation by in vitro experiments. Per a 10 three-dimensional structure was homology modelled using structure of anionic trypsin from pacific chum salmon as a template. Seven B cell epitopes (B-P1 to B-P7) were predicted by sequence and structure based methods. Three T cell epitopes (T-P8 to T-P10) were predicted by binding score and inhibitory concentration dependent prediction tools. Predicted epitopes were synthesized and biological activity was assessed by ELISA, ELISA inhibition and PBMC proliferation assays. B cell peptides B-P5, B-P6 and B-P7 showed significantly high IgE binding with pooled and individual cockroach hypersensitive patients’ sera while the T cell peptides did not show IgE binding. ELISA inhibition was performed to determine the potency of the predicted peptides. Fifty nanogram of peptide B-P7 was required for 50% IgE binding inhibition of surface bound Per a 10 whereas seventy five nanogram and ninety nanogram of B-P5 and B-P6 were required for the same respectively. Upon stimulation with T-P8 and T-P10 peptides, PBMCs from cockroach allergic patients’ (n = 15) showed significant lymphocyte proliferation and induced IL-4 and IL-5 cytokine release in the culture supernatant demonstrating Th2 dominant cell mediated response of predicted T cell peptides. In conclusion, Per a 10 3-D structure obtained by homology modelling was used to identify B and T cell epitopes, followed by in vitro validation. The identified peptides can be potentially used in designing diagnostics and therapies for cockroach allergy.     

Molecular basis of arthropod cross-reactivity: IgE-binding cross-reactive epitopes of shrimp,house dust mite and cockroach tropomyosins

BACKGROUND: Shrimp may cross-react with other crustaceans and mollusks and nonedible arthropods such as insects (cockroach and chironomids), arachnids (house dust mites) and even nematodes. Since the muscle protein tropomyosin has been implicated as a possible cross-reacting allergen, this study characterized the IgE-binding epitopes in shrimp tropomyosin, Pen a 1, that cross-react with other allergenic invertebrate tropomyosins in house dust mites (Der p 10, Der f 10) and cockroaches (Per a 7). Pen a 1-reactive sera from shrimp-allergic subjects were used to evaluate the effect on IgE binding of different amino acid substitutions in Pen a 1 epitopes based on homologous sequences in Per a 7 and Der p 10/Der f 10. METHODS: Peptides were synthesized spanning the length of Pen a 1 IgE-binding epitopes and amino acid substitutions were performed based on homologous amino acid sequences from Per a 7 and Der p 10/Der f 10. RESULTS: 7/8 individually recognized Pen a 1 epitopes (2, 3a, 3b, 4, 5a, 5b and 5c) had an identical amino acid sequence with lobster allergen, Hom a 1, 4/8 (3a, 3b, 4 and 5a) with Der p 10 and Der f 10, and 5/8 (2, 3a, 3b, 4 and 5a) with Per a 7. In addition, even homologous regions of other arthropod tropomyosins that differ in one or more amino acids from the sequences of Pen a 1 epitopes are still recognized by shrimp-allergic IgE antibodies. In total, shrimp-allergic sera recognize 6/8 peptides homologous to Pen a 1 epitopes in Per a 7, 7/8 in Der p 10/Der f 10, and 7/8 epitopes in Hom a 1. CONCLUSIONS: The IgE recognition by shrimp-allergic individuals of identified and/or similar amino acid sequences homologous to Pen a 1 epitopes in mite, cockroach and lobster tropomyosins are the basis of the in vitro cross-reactivity among invertebrate species. Based on amino acid sequence similarity and epitope reactivity, lobster tropomyosin has the strongest and cockroach the least cross-reactivity with shrimp. The clinical relevance of these cross-reactivities in developing allergic reactions to different arthropods needs to be determined.     

The Allergenic Potency of Japanese Hop Pollen Is Increasing With Environmental Changes in Korea

Purpose

The sensitization rate to Japanese Hop (Hop J) in respiratory allergy patients has increased in recent years in Korea. We evaluated changes in the allergenic potency of Hop J pollen collected in 1998 and 2009.

Methods

Thirty-five patients with allergic rhinitis and/or asthma were enrolled. Group I included 21 subjects sensitized to Hop J at an initial visit and group II included 14 subjects who developed a new sensitization. Hop J pollens were collected in 1998 and 2009 (98 and 09 extracts) and both urban and suburban environments (urban and suburban extracts). Serum specific IgE levels to Hop J pollen extracts were compared using an enzyme-linked immunosorbent assay (ELISA). IgE binding components were compared by IgE immunoblot analysis.

Results

Serum specific IgE levels to the 09 and urban extracts in both groups increased significantly compared to those of the 98 and suburban extracts. IgE immunoblot demonstrated that the major 10 kDa allergen was intensified in group I, while it was newly generated in group II with additional components ranging from 12-95 kDa. When the 98 and 09 extracts were compared, intensification of the major allergen of 09 extract had occurred in both groups. The IgE binding components of the urban extract was stronger than those of suburban one.

Conclusions

The allergenic potency of Hop J pollen may be increased with environmental changes.     

Garlic and onion sensitization among Saudi patients screened for food allergy: a hospital based study

Background

Detection of specific IgE antibodies against food materials indicates allergic sensitization. Some very widely consumed foods materials such as garlic and onion have rarely been investigated for their allergenic potential.

Objectives

To assess the presence of garlic and onion specific IgE antibodies in patients investigated for food allergy.

Methods

Radioallergosorbent test (RAST) results of 108 patients with clinical suspicion of food allergy who were specifically screened for garlic and onion specific IgE antibodies along with other food allergens were analyzed retrospectively at King Khalid University Hosptial between January 2008 and April 2009. This group of patients included 73 males and 35 females with mean age 27+13.2 years. Estimation of garlic and onion specific IgE antibodies was performed by radioallergosorbent test (RAST) using Pharmacia ImmunoCAP 250 analyzer.

Results

Out of the 108 patients 15 (13.8%) had garlic and onion specific IgE antibodies in their sera. Garlic specific IgE antibodies with the RAST scores between one to four were present in 14 and onion specific IgE were detected in 13 patients. For garlic specific IgEs majority of patients (08) had RAST score of one (0.35–0.69 kU/L) and for onion specific IgE antibodies seven patients had RAST score of two (0.70–3.49 kU/L). Among these patients 12 (80%) were found to have coexisting specific IgE antibodies against garlic and onion.

Conclusion

The presence of garlic and onion specific IgE antibodies in a sizeable number of patients indicate sensitization and allergenic potential of these food materials.     

Preparation and Characterization of an Extract of German Cockroach From a Korean Source

Purpose

The cockroach (CR) is an important cause of respiratory allergic disorders. We prepared a German CR extract in a standardized way and analyzed its allergenic properties.

Methods

The extract was prepared from German CR (Blattella germanica) obtained from a Korean colony, and its allergenic activity was compared with that of the commercial Hollister-Stier (HS) extract. The concentrations of Bla g 1 and Bla g 2 were measured, and an in vitro specific IgE binding inhibition assay was performed to assess IgE reactivity. Proteolytic activity was examined by gelatin zymography.

Results

Bla g 1 and Bla g 2 were detected at 405 U/mg and 273 ng/mg, respectively, in the Korean extract, and at 187 U/mg and 56 ng/mg, respectively, in the HS extract. The Korean extract showed 94.2% inhibition of IgE reactivity, as compared with the HS extract. A similar pattern of IgE-reactive bands was detected for the two extracts, indicating that their allergenic components are similar. The proteolytic activities of the Korean and HS extracts were found to be similar in gelatin zymography. The endotoxin levels in the Korean and HS extracts were 3,440 EU/mL and 6,580 EU/mL, respectively.

Conclusions

The German CR extract was prepared in a standardized way. The extract produced in this study will be useful for the development of allergy diagnostics and immunotherapeutic agents.     

Long-term Effects of Specific Allergen Immunotherapy Against House Dust Mites in Polysensitized Patients With Allergic Rhinitis

Purpose

Allergen-specific immunotherapy is the only currently available treatment to modify the natural history of allergic rhinitis (AR). If patients are polysensitized, it is difficult to identify the allergen causing the allergic symptoms. We evaluated the effectiveness of immunotherapy against house dust mites (HDMs) in AR patients polysensitized to both HDMs and seasonal allergens.

Methods

Thirty AR patients polysensitized to both HDMs and seasonal allergens (group A) and 30 patients sensitized to HDMs only (group B) were enrolled in this study. All subjects who received immunotherapy against HDMs for more than 2 years were evaluated by the multiple allergen simultaneous test (MAST) to determine the specific IgE level in luminescence units, total eosinophil counts in peripheral blood, serum total IgE, total nasal symptom scores, and the rhinoconjunctivitis quality of life questionnaire (RQLQ) before and after immunotherapy.

Results

There were no statistical differences in levels of total and specific IgE, or total eosinophil count between the two groups. The total nasal symptom scores, RQLQ and medication scores significantly decreased after immunotherapy in both groups, however no significant differences were noted between the two groups.

Conclusions

We determined that the primary causative allergen of AR in Seoul, Korea is perennial allergens, such as HDMs, rather than seasonal allergens. This study provides a reference for the selection of allergens to use in immunotherapy for polysensitized AR patients living in an urban environment.     

The Interaction Between Prenatal Exposure to Home Renovation and Reactive Oxygen Species Genes in Cord Blood IgE Response is Modified by Maternal Atopy

Purpose

Although home renovation exposure during childhood has been identified as a risk factor for the development of allergy, there is limited information on the association between prenatal exposure to home renovation and cord blood (CB) IgE response. The aims of this study were to identify the effect of prenatal exposure to home renovation on CB IgE levels, and to investigate whether this exposure interacts with neonatal genes and whether the effect can be modified by maternal atopy.

Methods

This study included 1,002 mother-neonate pairs from the COhort for Childhood Origin of Asthma and allergic diseases (COCOA). Prenatal environmental factors were collected using a questionnaire. The levels of CB IgE were measured by the ImmunoCAP system, and DNA was extracted from CB.

Results

Exposure to home renovation during the prenatal period was associated with significantly higher levels of CB IgE only in neonates from atopic mothers, and the effect of renovation exposure on CB IgE levels persisted from 31 months before birth. Furthermore, prenatal exposure to home renovation increased the risk of CB IgE response interacting with polymorphisms of NRF2 and GSTP1 genes only in neonates from atopic mothers.

Conclusions

Maternal atopy modified the effect of prenatal exposure to home renovation on CB serum IgE response as well as the interaction between the exposure and neonatal genes involved in the oxidative stress pathway. These findings suggest that the genetically susceptible offspring of atopic mothers may be more vulnerable to the effect of prenatal exposure to home renovation on the development of allergy.     

Clinical Features and the Diagnostic Value of Component Allergen-Specific IgE in Hymenoptera Venom Allergy

Purpose

Although patient history is vital for the diagnosis of hymenoptera venom allergy, specific IgE detection is also important to identify the culprit insect and monitor the effect of immunotherapy. We evaluated the diagnostic value of serum-specific IgE detection of hymenoptera venom component allergens and documented changes in allergen-specific IgE after immunotherapy.

Methods

Fifty-six hymenoptera venom allergy patients receiving venom immunotherapy were recruited from Ajou University Hospital, Korea. The clinical manifestations of the patients were noted, and serum-specific IgE detection was performed, using conventional venom extracts as well as component allergens. Data were analyzed retrospectively.

Results

A total of 35 (62.5%) patients were male, and 33 (73.3%) patients were atopic. The mean patient age was 44.9±13.8 years. Localized reactions occurred in 23.2% of patients, and systemic reactions occurred in 76.8%. The most common clinical manifestations included skin involvement, such as urticaria and angioedema, and respiratory involvement. Yellow jackets were the most frequent culprit insect, followed by yellow hornets, white-faced hornets, honeybees, and paper wasps, as determined at the time of diagnosis. Double sensitization to both Apidae and Vespidae species was detected in 70.9% of patients. The positive predictive values (PPV) of rVes v 5-specific and rPol d 5-specific IgE detection were 85.7% and 87.5%, respectively, which correlated well with conventional venom extract-specific IgE detection (r=0.762 and r=0.757, respectively). In contrast, the PPV of rApi m 1-specific IgE detection at the time of diagnosis was 34.8%. Three years of venom immunotherapy resulted in decreased venom-specific IgE, particularly IgE specific for Vespidae venom components.

Conclusions

Stings by yellow jackets and male sex may be risk factors for hymenoptera venom allergy in Korea. Vespidae component-specific IgE, but not Apidae component-specific IgE, had diagnostic and monitoring value in hymenoptera venom allergy comparable to that of conventional hymenoptera venom extract-specific IgE.     

IgE-binding epitopes of the American cockroach Per a 1 allergen

Cockroach is one of the major indoor allergens for IgE-mediated allergic respiratory illnesses throughout the world. The American cockroach (Periplaneta americana) Per a 1 allergen is antigenically cross-reactive with the German cockroach (Blattella germanica) Bla g 1 allergen. The aim of this study was to identify linear B cell epitopes of Per a 1 that are recognized by human IgE. Per a 1 deletion mutants were generated from the recombinant Per a 1.0104 allergen (274 amino acid residues), and antigenicities were assessed by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and binding inhibition. Human atopic sera were not able to recognize deletion mutants consisting of amino acids 1-77, 86-205, and 200-266. However, human sera did recognize the N-terminal mutant containing amino acids 1-87 and the C-terminal mutant containing amino acids 200-274, demonstrating positive IgE binding that was heterogeneously distributed among the different sera tested. Amino acid residues 78-85 and 267-274, containing internal repeats, were shown to be required for IgE binding to the Per a 1.0104 protein. Two peptides corresponding to these IgE-binding amino acid sequences were synthesized. Peptide 78-85 showed a positive IgE interaction with 80% of the sera, while peptide 267-274 was capable of IgE binding to all of the sera tested. Moreover, preincubation of atopic sera with IgE-positive recombinants and peptides resulted in marked inhibition of the IgE binding to purified Per a 1.0104 allergen. Amino acid sequences 78LIRALFGL85 and 267IRSWFGLP1274 of the American cockroach Per a 1.0104 allergen were involved in IgE binding. These findings will advance the understanding of the specific reactivity of the epitopes of cockroach allergens, thereby contributing to the development of specific immunotherapies for clinical use.     

Association of Antioxidants With Allergic Rhinitis in Children From Seoul

Purpose

The prevalence of allergic diseases has risen over the last few decades. Many factors, including environmental factors such as those related to diet, have been considered. Among dietary factors, intake of antioxidant-related nutrients has been associated with the risk of allergic disease. We investigated the association of antioxidant nutritional status with allergic rhinitis (AR) in Korean schoolchildren aged 6-12 years.

Methods

Subjects were 4,554 children in Seoul, Korea. The risk of allergic disease was measured using the Korean version of the International Study of Asthma and Allergies in Childhood, and dietary intake was measured by a semi-quantitative food frequency questionnaire. Intake of vitamins A (including retinol and β-carotene), C, and E was used in the analysis.

Results

Vitamin C intake was negatively associated with an increased risk of current symptoms (adjusted odds ratio, 0.886; 95% confidence interval, 0.806-0.973). There was no association between AR and intake of vitamin A, retinol, β-carotene, or vitamin E. Total serum IgE level and sensitization to allergen did not differ according to nutrient intake.

Conclusions

The group of children with increased vitamin C consumption had fewer AR symptoms, despite the lack of a difference in total serum IgE level or allergen sensitization. These findings suggest that nutrient intake, especially that of vitamin C, influences AR symptoms.     

Effect of Amino Acid Polymorphisms of House Dust Mite Der p 2 Variants on Allergic Sensitization

Purpose

The sequence variations of the Der p 2 allergen of Dermatophagoides pteronyssinus diverge along 2 pathways with particular amino acid substitutions at positions 40,47,111, and 114. The environmental prevalence and IgE binding to Der p 2 variants differ among regions. To compare IgE binding to Der p 2 variants between sera from Bangkok, Thailand and Perth, Western Australia with different variants and to determine the variant-specificity of antibodies induced by vaccination with recombinant variants.

Methods

The structures of recombinant variants produced in yeast were compared by circular dichroism and 1-anilinonaphthalene 8-sulfonic acid staining of their lipid-binding cavity. Sera from subjects in Bangkok and Perth where different variants are found were compared by the affinity (IC₅₀) of IgE cross-reactivity to different variants and by direct IgE binding. Mice were immunized with the variants Der p 2.0101 and Der p 2.0110, and their IgG binding to Der p 2.0103, 2.0104, and 2.0109 was measured.

Results

The secondary structures of the recombinant variants resembled the natural allergen but with differences in ANS binding. The IC₅₀ of Der p 2.0101 required 7-fold higher concentrations to inhibit IgE binding to the high-IgE-binding Der p 2.0104 than for homologous inhibition in sera from Bangkok where it is absent, while in sera from Perth that have both variants the IC₅₀ was the same and low. Reciprocal results were obtained for Der p 2.0110 not found in Perth. Direct binding revealed that Der p 2.0104 was best for detecting IgE in both regions, followed by Der p 2.0101 with binding to other variants showing larger differences. Mouse anti-Der p 2.0101 antibodies had a high affinity of cross-reactivity but bound poorly to other variants.

Conclusions

The affinity of IgE antibody cross-reactivity, the direct IgE binding, and the specificities of antibodies induced by vaccination show that measures of allergic sensitization and therapeutic strategies could be optimized with knowledge of Der p 2 variants.     

The Influence of IgE on Cultured Human Mast Cells

Purpose

The mast cell plays a pivotal role in the human immune response. Crosslinking of 2 IgE molecules bound to the high affinity IgE receptor (FcεRI) on the surface of the mast cell results in mast cell degranulation and the release of several proinflammatory mediators. Patients with type-I allergy have increased levels of IgE in the blood compared to healthy individuals.

Methods

In a 6-week culture system of stem cells to human mast cells we investigated the effect of the concentration of IgE. The mast cells were cultured with different concentrations of IgE for the last 10 days of the maturation period. It was observed how the IgE concentration affects the histamine release, FcεRI density on the mast cell surface and the concentration of other mediators.

Results

A clear correlation between IgE concentration in culture medium and the release of histamine upon activation was observed. It showed a bell-shaped dose response curve, with maximal response around an IgE-concentration of 250 ng/mL. Furthermore, the sensitivity of the mast cells and surface density of FcεRI on mast cell surface was also influenced by the IgE concentration in the culture medium.

Conclusions

IgE in the culture medium during the last 10 days of mast cell maturation influences the release of the preformed mediator histamine after mast cell activation and the density of FcεRI on the mast cell surface. The release of the de novo synthetized mediator prostaglandin D₂ and the expression of chymase and tryptase are not influenced by IgE in culture medium.     

Screening for hen's egg and chicken meat specific IgE antibodies in Saudi patients with allergic disorders

Background

Allergy to hen''s egg and meat contributes significantly to the manifestations of food allergy all over the world.

Objectives

This study was performed to assess the presence of hen''s egg and meat specific IgE antibodies among patients investigated for various allergic disorders.

Methods

This is a retrospective study performed at King Khalid University Hosptial, Riyadh. Data from 421 patients with allergic disorders screened for food specific IgE antibodies between January 2009 and March 2011 were analyzed. Sixty (14.25%) patients including 42 males and 18 females with the mean age (sd) of 7.5 (7.4) years were found to have specific IgE antibodies against hen''s egg and chicken meat. There were 56 (93.3%) children and 4 (6.7%) adult patients. Specific IgE antibodies were measured by radioallergosorbent test (RAST) using Pharmacia ImmunoCAP 250 analyzer.

Results

Atopic dermatitis was the most common (55%) clinical condition. Out of the total 60 patients harboring hen''s egg and chicken meat specific IgE antibodies high levels of egg white, yolk and chicken meat specific IgEs were detected in 58 (96.6%), 37 (61.6%) and 6 (10%) patients respectively. Both the egg white and yolk antibodies coexisted in 35 (58.3%) patients.

Conclusion

Sensitization against hen''s egg was higher compared to the chicken meat. Egg white sensitization higher than the egg yolk particularly in Saudi children with food related allergic disorders.