The Efficacy & Molecular Mechanisms of a Terpenoid Compound Ganoderic Acid C1 on Corticosteroid-Resistant Neutrophilic Airway Inflammation: In vivo and in vitro Validation.

Introduction: Neutrophil predominant airway inflammation is associated with severe and steroid-resistant asthma clusters. Previously, we reported efficacy of ASHMI, a three-herb TCM asthma formula in a steroid-resistant neutrophil-dominant murine asthma model and further identified Ganoderic Acid C1 (GAC1) as a key ASHMI active compound in vitro. The objective of this study is to investigate GAC1 effect on neutrophil-dominant, steroid-resistant asthma in a murine model. Methods: In this study, Balb/c mice were systematically sensitized with ragweed (RW) and alum and intranasally challenged with ragweed. Unsensitized/PBS challenged mice served as normal controls. Post sensitization, mice were given 4 weeks of oral treatment with GAC1 or acute dexamethasone (Dex) treatment at 48 hours prior to challenge. Pulmonary cytokines were measured by ELISA, and lung sections were processed for histology by H&E staining. Furthermore, GAC1 effect on MUC5AC expression and on reactive oxygen species (ROS) production in human lung epithelial cell line (NCI-H292) was determined by qRT-PCR and ROS assay kit, respectively. Computational analysis was applied to select potential targets of GAC1 in steroid-resistant neutrophil-dominant asthma. Molecular docking was performed to predict binding modes between GAC1 and Dex with TNF-α. Results: The result of the study showed that chronic GAC1 treatment, significantly reduced pulmonary inflammation (P < 0.01-0.001 vs Sham) and airway neutrophilia (P < 0.01 vs Sham), inhibited TNF-α, IL-4 and IL-5 levels (P < 0.05-0.001 vs Sham). Acute Dex treatment reduced eosinophilic inflammation and IL-4, IL-5 levels, but had no effect on neutrophilia and TNF-α production. GAC1 treated H292 cells showed decreased MUC5AC gene expression and production of ROS (P < 0.001 vs stimulated/untreated cells). Molecular docking results showed binding energy of complex GAC1-TNF was -10.8 kcal/mol. Discussion: GAC1 may be a promising anti-asthma botanical drug for treatment of steroid-resistant asthma.

Mapping Sequential IgE-Binding Epitopes on Major and Minor Egg Allergens.

INTRODUCTION: Molecular studies of hen's egg allergens help define allergic phenotypes, with IgE to sequential (linear) epitopes on the ovomucoid (OVM) protein associated with a persistent disease. Epitope profiles of other egg allergens are largely unknown. The objective of this study was to construct an epitope library spanning across 7 allergens and further evaluate sequential epitope-specific (ses-)IgE and ses-IgG4 among baked-egg reactive or tolerant children. METHODS: A Bead-Based Epitope Assay was used to identify informative IgE epitopes from 15-mer overlapping peptides covering the entire OVM and ovalbumin (OVA) proteins in 38 egg allergic children. An amalgamation of 12 B-cell epitope prediction tools was developed using experimentally identified epitopes. This ensemble was used to predict epitopes from ovotransferrin, lysozyme, serum albumin, vitellogenin-II fragment, and vitellogenin-1 precursor. Ses-IgE and ses-IgG4 repertoires of 135 egg allergic children (82 reactive to baked-egg, the remaining 52 tolerant), 46 atopic controls, and 11 healthy subjects were compared. RESULTS: 183 peptides from OVM and OVA were screened and used to create an aggregate algorithm, improving predictions of 12 individual tools. A final library of 65 sequential epitopes from 7 proteins was constructed. Egg allergic children had higher ses-IgE and lower ses-IgG4 to predominantly OVM epitopes than both atopic and healthy controls. Baked-egg reactive children had similar ses-IgG4 but greater ses-IgE than tolerant group. A combination of OVA-sIgE with ses-IgEs to OVM-023 and OVA-028 was the best predictor of reactive phenotype. CONCLUSION: We have created a comprehensive epitope library and showed that ses-IgE is a potential biomarker of baked-egg reactivity.

Epicutaneous immunization using synthetic virus-like particles efficiently boosts protective immunity to respiratory syncytial virus.

Despite the substantial health and economic burden caused by RSV-associated illness, no vaccine is available. The sole licensed treatment (palivizumab), composed of a monoclonal neutralizing antibody, blocks the fusion of the virus to the host cell but does not prevent infection. The development of a safe and efficacious RSV vaccine is therefore a priority, but also a considerable challenge, and new innovative strategies are warranted. Most of the adult population encounter regular RSV infections and can elicit a robust neutralizing antibody response, but unfortunately it wanes over time and reinfections during subsequent seasons are common. One approach to protect the mother and young infant from RSV infection is to administer a vaccine capable of boosting preexisting RSV immunity during pregnancy, which would provide protection to the fetus through passive transfer of maternal antibodies, thus preventing primary RSV infection in newborns during their first months of life. Here, we describe the preclinical evaluation of an epicutaneous RSV vaccine booster that combines epicutaneous patches as a delivery platform and a Synthetic Virus-Like Particles (SVLP)-based vaccine displaying multiple RSV F-protein site II (FsII, palivizumab epitope) mimetic as antigen (V-306). We demonstrated in mice that epicutaneous immunization with V-306 efficiently boosts preexisting immunity induced by the homologous V-306 administered subcutaneously. This boosting was characterized by a significant increase in F- and FsII-specific antibodies capable of competing with palivizumab for its target antigen and neutralize RSV. More importantly, epicutaneous booster immunization with V-306 significantly decreased lung viral replication in experimental mice after intranasal RSV challenge, without inducing enhanced RSV disease. In conclusion, an epicutaneous booster vaccine based on V-306 is safe and efficacious in enhancing RSV preexisting immunity in mice. This needle-free vaccine candidate would be potentially suited as a booster vaccine for vulnerable populations such as young infants via pregnant women, and the elderly.

Treatment of Intestinal Inflammation With Epicutaneous Immunotherapy Requires TGF-ß and IL-10 but Not Foxp3+ Tregs.

Background: Inflammatory bowel disease (IBD) involves an increase in T effector cells in the intestines that disrupts the normal balance with T regulatory cells (Tregs). A therapy that restores this balance has the potential to treat IBD. We have shown that epicutaneous exposure to OVA induces Tregs that are able to induce tolerance. The Tregs also migrate to the intestines where they alleviate colitis in mice, demonstrating the potential for skin induced Tregs to treat intestinal inflammation. We investigated the role of Foxp3, IL-10, and TGF-ß in the suppression of colitis by epicutaneous immunotherapy (ET). Methods: RAG1-/- mice were transferred with CD4+CD45RBhi T cells from wild type mice to induce colitis. To determine whether Foxp3+ Tregs, IL-10-, or TGF-ß-producing Tregs were necessary, Foxp3-DTR, IL-10-/-, or CD4-dnTGFBRII mice were immunized with OVA and OVA TCR enriched T cells were added. As control groups, some mice were given OVA TCR enriched T cells from wild type mice or no OVA TCR enriched T cells. Half of the mice in each group were then exposed on the skin to Viaskin patches containing OVA weekly for 3 weeks. Mice given OVA TCR enriched T cells from Foxp3-DTR mice were given diphtheria toxin (DT) or not in addition to ET. Mice were assessed for weight loss, colon length, colonic cytokine production, and histological inflammation. Results: ET, after injection with OVA TCR enriched T cells derived from wild type mice, prevented weight loss, decreased colonic inflammatory cytokine production and histological colitis. ET in the absence of the OVA TCR enriched T cells did not alleviate colitis. ET, after injection with OVA TCR enriched T cells derived from Foxp3-DTR mice, prevented weight loss, decreased colonic inflammatory cytokine production, and histological colitis. Ablation with DT did not impair the ability of ET to alleviate colitis. ET failed to alleviate colitis when OVA TCR enriched T cells were derived from IL-10-/- or CD4-dnTGFBRII mice. Conclusions: ET through induction of Tregs, which produce IL-10 and TGF-ß, could be a promising treatment for IBD.

A new Luminex-based peptide assay to identify reactivity to baked, fermented, and whole milk.

BACKGROUND: The majority of children with cow's milk allergy (CMA) tolerate baked milk. However, reactivity to fermented milk products such as yogurt/cheese has not been previously evaluated. We sought to determine whether children with CMA could tolerate yogurt/cheese and whether a patient's IgE and IgG4-binding pattern to milk protein epitopes could distinguish clinical reactivity. METHODS: Four groups of reactivity were identified by Oral food challenge: baked milk reactive, fermented milk reactive, whole milk reactive, and outgrown. sIgE and sIgG4 binding to milk protein epitopes were assessed with a novel Luminex-based peptide assay (LPA). Using machine learning techniques, a model was developed to predict different degrees of CMA. RESULTS: The baked milk reactive patients demonstrated the highest degree of IgE epitope binding, which was followed sequentially by fermented milk reactive, whole milk reactive, and outgrown. Data were randomly divided into two groups with 75% of the data utilized for model development (n = 68) and 25% for testing (n = 21). All 68 children used for training were correctly classified with models using IgE and IgG4 epitopes. The average cross-validation accuracy was much higher for models using IgE plus IgG4 epitopes by LPA (84.8%), twice the performance of the serum component proteins assayed by UniCAP (41.9%). The performance of the model on "unseen data" was tested using the 21 withheld patients, and the accuracy of IgE was 86% (AUC = 0.89) while of IgE+IgG4 model was 81% (AUC = 0.94). CONCLUSION: Using a novel high-throughput LPA, we were able to distinguish the diversity of IgE/IgG4 binding to epitopes in the varying CMA phenotypes. LPA is a promising tool to predict correctly different degrees of CMA.

Predicting development of sustained unresponsiveness to milk oral immunotherapy using epitope-specific antibody binding profiles.

BACKGROUND: In a recent trial of milk oral immunotherapy (MOIT) with or without omalizumab in 55 patients with milk allergy treated for 28 months, 44 of 55 subjects passed a 10-g desensitization milk protein challenge; 23 of 55 subjects passed the 10-g sustained unresponsiveness (SU) challenge 8 weeks after discontinuing MOIT. OBJECTIVE: We sought to determine whether IgE and IgG4 antibody binding to allergenic milk protein epitopes changes with MOIT and whether this could predict the development of SU. METHODS: By using a novel high-throughput Luminex-based assay to quantitate IgE and IgG4 antibody binding to 66 sequential epitopes on 5 milk proteins, serum samples from 47 subjects were evaluated before and after MOIT. Machine learning strategies were used to predict whether a subject would have SU after 8 weeks of MOIT discontinuation. RESULTS: MOIT profoundly altered IgE and IgG4 binding to epitopes, regardless of treatment outcome. At the initiation of MOIT, subjects achieving SU exhibited significantly less antibody binding to 40 allergenic epitopes than subjects who were desensitized only (false discovery rate ≤ 0.05 and fold change > 1.5). Based on baseline epitope-specific antibody binding, we developed predictive models of SU. Using simulations, we show that, on average, IgE-binding epitopes alone perform significantly better than models using standard serum component proteins (average area under the curve, >97% vs 80%). The optimum model using 6 IgE-binding epitopes achieved a 95% area under the curve and 87% accuracy. CONCLUSION: Despite the relatively small sample size, we have shown that by measuring the epitope repertoire, we can build reliable models to predict the probability of SU after MOIT. Baseline epitope profiles appear more predictive of MOIT response than those based on serum component proteins.

PDL2+ CD11b+ dermal dendritic cells capture topical antigen through hair follicles to prime LAP+ Tregs.

The skin immune system must discriminate between innocuous antigens and pathogens. Antigen applied topically using a Viaskin® patch elicits immune tolerance that can suppress colitis and food allergy. Here we show how topical antigen is acquired and presented by dendritic cells in the skin. Topical antigen is acquired by Langerhans cells (LC) and CD11b+ cDC2s but not cDC1s, and both  LCs and CD11b+ cDC2s reaching the lymph node can prime T cells and expand LAP+ Tregs. However, LCs are neither required nor sufficient for T cell priming, and have no role in tolerance induction. Conversely, IRF-4-dependent cDC2s are required for T cell priming. Acquisition of antigen in the dermis, delivery to the draining lymph node, and generation of tolerance are all absent in hairless mice. These results indicate an important function for hair follicle niche and CD11b+ cDC2s in antigen acquisition, and in generation of primary immune tolerance to topical antigens.

Secreted IgD Amplifies Humoral T Helper 2 Cell Responses by Binding Basophils via Galectin-9 and CD44.

B cells thwart antigenic aggressions by releasing immunoglobulin M (IgM), IgG, IgA, and IgE, which deploy well-understood effector functions. In contrast, the role of secreted IgD remains mysterious. We found that some B cells generated IgD-secreting plasma cells following early exposure to external soluble antigens such as food proteins. Secreted IgD targeted basophils by interacting with the CD44-binding protein galectin-9. When engaged by antigen, basophil-bound IgD increased basophil secretion of interleukin-4 (IL-4), IL-5, and IL-13, which facilitated the generation of T follicular helper type 2 cells expressing IL-4. These germinal center T cells enhanced IgG1 and IgE but not IgG2a and IgG2b responses to the antigen initially recognized by basophil-bound IgD. In addition, IgD ligation by antigen attenuated allergic basophil degranulation induced by IgE co-ligation. Thus, IgD may link B cells with basophils to optimize humoral T helper type 2-mediated immunity against common environmental soluble antigens.

Food allergy.

Food allergies manifest in a variety of clinical conditions within the gastrointestinal tract, skin and lungs, with the most dramatic and sometimes fatal manifestation being anaphylactic shock. Major progress has been made in basic, translational and clinical research, leading to a better understanding of the underlying immunological mechanisms that lead to the breakdown of clinical and immunological tolerance against food antigens, which can result in either immunoglobulin E (IgE)-mediated reactions or non-IgE-mediated reactions. Lifestyle factors, dietary habits and maternal-neonatal interactions play a pivotal part in triggering the onset of food allergies, including qualitative and quantitative composition of the microbiota. These factors seem to have the greatest influence early in life, an observation that has led to the generation of hypotheses to explain the food allergy epidemic, including the dual-allergen exposure hypothesis. These hypotheses have fuelled research in preventive strategies that seek to establish desensitization to allergens and/or tolerance to allergens in affected individuals. Allergen-nonspecific therapeutic strategies have also been investigated in a number of clinical trials, which will eventually improve the treatment options for patients with food allergy.

Mechanistic correlates of clinical responses to omalizumab in the setting of oral immunotherapy for milk allergy.

BACKGROUND: In our recent clinical trial, the addition of omalizumab to oral immunotherapy (OIT) for milk allergy improved safety, but no significant clinical benefit was detected. OBJECTIVE: We sought to investigate mechanisms by which omalizumab modulates immunity in the context of OIT and to identify baseline biomarkers that predict subgroups of patients most likely to benefit from omalizumab. METHODS: Blood was obtained at baseline and multiple time points during a placebo-controlled trial of OIT for milk allergy in which subjects were randomized to receive omalizumab or placebo. Immunologic outcomes included measurement of basophil CD63 expression and histamine release and casein-specific CD4+ regulatory T-cell proliferation. Biomarkers were analyzed in relationship to measurements of safety and efficacy. RESULTS: Milk-induced basophil CD63 expression was transiently reduced in whole blood samples from both omalizumab- and placebo-treated subjects. However, IgE-dependent histamine release increased in washed cell preparations from omalizumab- but not placebo-treated subjects. No increase in regulatory T-cell frequency was evident in either group. Subjects with lower rates of adverse reactions, regardless of arm, experienced better clinical outcomes. Pre-OIT basophil reactivity positively associated with occurrence of symptoms during OIT, whereas the baseline milk IgE/total IgE ratio correlated with the likelihood of achieving sustained unresponsiveness. A combination of baseline basophil and serologic biomarkers defined a subset of patients in which adjunctive therapy with omalizumab was associated with attainment of sustained unresponsiveness and a reduction in adverse reactions. CONCLUSIONS: Combining omalizumab therapy with milk OIT led to distinct alterations in basophil reactivity but not T-cell responses. Baseline biomarkers can identify subjects most likely to benefit from adjunctive therapy with omalizumab.

Basophil Degranulation Assay.

Basophil degranulation assay has gained importance over the last decade in both diagnosis of food allergy and evaluation of progression of immunotherapy. This assay involves the identification and quantification of the expression of CD63 molecule on basophil membrane. CD63 is a marker of multivesicular bodies that is exposed to cell membrane during the process of degranulation in which the contents of basophil granules are released. This chapter describes the methodology for performing this assay.

IgE Epitope Mapping Using Peptide Microarray Immunoassay.

IgE epitope mapping has the potential to become an additional tool for food allergy diagnosis/prognosis and to lead to a better understanding of the pathogenesis and tolerance induction of food allergy. Due to its ability to screen thousands of targets in parallel using small volumes of sample, peptide microarray has greatly facilitated large-scale IgE epitope mapping. In the past 10 years, we have developed and optimized a reliable and sensitive peptide microarray immunoassay, which has been successfully applied for IgE epitope mapping of many food allergens in our lab. Here, we describe the method of performing the peptide microarray immunoassay for IgE epitope mapping. In addition, we have upgraded the microarray platform to measure antibody affinity by adding one additional competition step, which is also described in this chapter.

T-Cell Proliferation Assay: Determination of Immunodominant T-Cell Epitopes of Food Allergens.

Characterization of allergen-specific T cells is critical to understand their contribution to disease pathogenesis. The identification of immunodominant T-cell epitopes is crucial for development of T-cell-based vaccines. Peptide-specific T-cell proliferation studies are usually performed in a library of short synthetic peptides (15mer or 20mer) with 3 or 5 offset spanning the entire length of the allergen. T-cell peptide epitopes lack the primary and tertiary structure of the native protein to cross-link IgE, but retain the ability to stimulate T cells. The peptides sequences can also be obtained either by in silico approaches and in vitro binding assays. The efficacy of T-cell epitope-based peptide immunotherapy has been proven in certain allergies. The present methodology describes T-cell proliferation assays using whole blood sample from allergic subjects.

Epicutaneous immunotherapy induces gastrointestinal LAP+ regulatory T cells and prevents food-induced anaphylaxis.

BACKGROUND: The attempt to induce oral tolerance as a treatment for food allergy has been hampered by a lack of sustained clinical protection. Immunotherapy by nonoral routes, such as the skin, may be more effective for the development of maintained tolerance to food allergens. OBJECTIVE: We sought to determine the efficacy and mechanism of tolerance induced by epicutaneous immunotherapy (EPIT) in a model of food-induced anaphylaxis. METHODS: C3H/HeJ mice were sensitized to ovalbumin (OVA) orally or through the skin and treated with EPIT using OVA-Viaskin patches or oral immunotherapy using OVA. Mice were orally challenged with OVA to induce anaphylaxis. Antigen-specific regulatory T (Treg)-cell induction was assessed by flow cytometry using a transgenic T-cell transfer model. RESULTS: By using an adjuvant-free model of food allergy generated by epicutaneous sensitization and reactions triggered by oral allergen challenge, we found that EPIT induced sustained protection against anaphylaxis. We show that the gastrointestinal tract is deficient in de novo generation of Treg cells in allergic mice. This defect was tissue-specific, and epicutaneous application of antigen generated a population of gastrointestinal-homing LAP+Foxp3- Treg cells. The mechanism of protection was found to be a novel pathway of direct TGF-ß-dependent Treg-cell suppression of mast cell activation, in the absence of modulation of T- or B-cell responses. CONCLUSIONS: Our data highlight the immune communication between skin and gastrointestinal tract, and identifies novel mechanisms by which epicutaneous tolerance can suppress food-induced anaphylaxis.

Peanut T-cell epitope discovery: Ara h 1.

BACKGROUND: Identification of potential T-cell epitopes in the peanut major allergens is essential for development of peptide-based immunotherapy. Traditional methods of T-cell epitope discovery use overlapping short peptides spanning the full length of the protein in T-cell proliferation assays. Because large proteins, such as Ara h 1, require a large number of peptides, this limits screening to a small number of allergic subject-derived T-cell lines. OBJECTIVE: We sought to identify candidate peptides of Ara h 1 that display promiscuous binding to MHC class II and induce TH2 cytokine production by T cells. METHODS: In silico MHC class II binding prediction was performed with NetMHCIIpan 2.0 (peptide length, 15; 1-mer offset) and the most abundant class II alleles in the North American population and with an in vitro MHC class II peptide reporter assay performed in parallel, which used synthetic 15-mer peptides offset by 5 mer spanning the protein. High-resolution MHC class II typing and a T-cell proliferation assay using preselected peptides were performed with PBMCs from 98 subjects with peanut allergy and 14 healthy control subjects. IL-4, IL-13, IL-5, IFN-γ, and TNF-α levels were measured in culture supernatants. RESULTS: Thirty-six Ara h 1 peptides were identified by using in silico predictions and MHC class II binding assays. In combination with T-cell proliferation and cytokines secreted in T-cell assays, we have identified 4 vaccine candidate Ara h 1 peptides. CONCLUSIONS: Preselection of peptides by using in silico and in vitro approaches in combination with conventional methods appears to be an effective strategy for identifying peanut T-cell peptide vaccine candidates.

Genome-wide association analysis of eosinophilic esophagitis provides insight into the tissue specificity of this allergic disease.

Eosinophilic esophagitis (EoE) is a chronic inflammatory disorder associated with allergic hypersensitivity to food. We interrogated >1.5 million genetic variants in EoE cases of European ancestry and subsequently in a multi-site cohort with local and out-of-study control subjects. In addition to replicating association of the 5q22 locus (meta-analysis P=1.9×10(-16)), we identified an association at 2p23 spanning CAPN14 (P=2.5×10(-10)). CAPN14 was specifically expressed in the esophagus, was dynamically upregulated as a function of disease activity and genetic haplotype and after exposure of epithelial cells to interleukin (IL)-13, and was located in an epigenetic hotspot modified by IL-13. Genes neighboring the top 208 EoE-associated sequence variants were enriched for esophageal expression, and multiple loci for allergic sensitization were associated with EoE susceptibility (4.8×10(-2)

Effect of Antiasthma Simplified Herbal Medicine Intervention on neutrophil predominant airway inflammation in a ragweed sensitized murine asthma model.

BACKGROUND: Neutrophil-predominant asthma is less responsive to steroids and associated with poorer disease control. The effects of Antiasthma Simplified Herbal Medicine Intervention (ASHMI), a traditional Chinese medicine formula reported to be efficacious in asthmatic patients and murine asthma models, on neutrophil predominant asthma are unknown. OBJECTIVE: To determine the effects of standard ASHMI and refined formula ASHMI (ASHMI(II)) in a neutrophil-predominant murine model of ragweed (RW) asthma and explore underlying mechanisms. METHODS: BALB/c mice were systemically sensitized, intranasally challenged with RW extract, and orally treated with ASHMI, ASHMI(II), or vehicle (water). In a separate experiment, some RW sensitized mice were treated with dexamethasone before challenge. After RW challenge, airway hyperreactivity (AHR), total and differential bronchoalveolar lavage fluid leukocyte counts, lung histologic features, and bronchoalveolar lavage fluid cytokine and chemokine levels were assessed. RW stimulation of the murine macrophage cell line RAW264.7 was used to determine effects of ASHMI active compound ganoderic acid C1 (GAC1) on tumor necrosis factor α (TNF-α) production and regulation of phosphorylated IκB and histone deacetylase 2 (HDAC2) levels. RESULTS: ASHMI and ASHMI(II) markedly reduced AHR, mucous production, neutrophilic inflammation, and TNF-α, interleukin 8, and interleukin 17 levels and decreased eosinophilic inflammation and TH2 responses in vivo (P < .01-.001 for all). GAC1 inhibited TNF-α production in RW-stimulated RAW264.7 cells in association with suppression of phosphorylated IκB and increased HDAC2 expression. Dexamethasone failed to reduce AHR and neutrophilic inflammation. CONCLUSION: ASHMI treatment was efficacious in a murine model of neutrophil-predominant asthma via modulation of innate chemokines, TH2 responses, nuclear factor-κB, and HDAC2. ASHMI, and/or its constituent GAC1, may be a valuable option for treating neutrophil-predominant asthma.

Potential non-T cells source of interleukin-4 in food allergy.

BACKGROUND: Recently, a study from the Consortium of Food Allergy Research (CoFAR) showed that allergen-induced IL-4 expression in CD25(+) mononuclear cells was increased in allergic patients. However, they did not find the expected increase in GATA-3 expression, suggesting that allergen-induced IL-4 might not be of T-cell origin. We sought to determine whether other cell types were responsible for the increased IL-4 expression in the CD25(+) cell population. METHODS: Comparing six allergic patients and six healthy controls, we analyzed the CD25(+) isolated population from PBMC for the presence of potential IL-4-expressing non-T cells. We also compared spontaneous expression levels of surface markers (CD203c, CD63, CD25, and HLA-DR) on basophils from whole blood of 42 peanut-allergic patients and from 12 non-atopic controls. Expression of these markers was also evaluated following basophil activation in eight peanut-allergic patients selected from the previous cohort. RESULTS: In addition to CD4(+) T cells, a substantial proportion of non-T cells were found in the CD25(+) -isolated cell population: basophils, NK, and NK-T cells with a mean percentage ± s.e.m. of 5.24 ± 0.63%, 6.65 ± 1.01%, and 6.01 ± 1.04%, respectively. The majority of these cells exhibited positive intracytoplasmic staining for IL-4. Expression of CD63 and CD25 was significantly higher in allergic patients compared with controls (p < 0.05). Interestingly, we found a significantly higher proportion of activated basophils expressing HLA-DR, compared with non-activated basophils (p < 0.05). CONCLUSIONS: Our results support the suggested key role of non-T cells secreting IL-4 in food allergy, particularly basophils, which may also play a central role in antigen presentation.

In vitro digestibility of bovine ß-casein with simulated and human oral and gastrointestinal fluids. Identification and IgE-reactivity of the resultant peptides.

Stability during digestion is considered an important feature in determining the allergenicity of food proteins. This study aimed to provide an immunological characterisation of the digestion products of the major cow's milk allergen ß-casein (ß-CN) produced by in vitro orogastrointestinal hydrolysis with simulated and human digestive fluids. ß-CN was unaffected by oral digestion, but quickly broke down during the early stages of gastric digestion. The degradation with human fluids was faster than that with commercial enzymes. There were similarities in the peptide patterns of the hydrolysates produced in both models, showing 20 peptides in common after gastric digestion. After gastroduodenal digestion, the human fluids gave less numerous and shorter peptides. The IgE binding of most of the individual sera used to the hydrolysates produced with simulated and human fluids increased at the end of the gastric phase and decreased when the duodenal digestion was completed. Two IgE-binding synthetic peptides: ß-CN (57-68) and ß-CN (82-93), which matched fragments released by ß-CN following in vitro digestion with simulated and human fluids, consisted of the most immunoreactive areas of the protein. The similarities found between the in vitro simulated digestion system and that using human digestive fluids suggest that the former would provide a reasonably good estimation of the potential allergenicity of protein digests.