Characterization of ovomucoid-specific T-cell lines and clones from egg-allergic subjects

Can we produce true tolerance in patients with food allergy?

Immune tolerance is defined as nonresponsiveness of the adaptive immune system to antigens. Immune mechanisms preventing inappropriate immune reactivity to innocuous antigens include deletion of reactive lymphocytes and generation of regulatory T (Treg) cells. The normal response to food antigens is the generation of antigen-specific Treg cells. In patients with food allergy, the dominant immune response is a T(H)2-skewed T-cell response and the generation of food-specific IgE antibodies from B cells. It is not known whether a failure of the Treg cell response is behind this inappropriate immune response, but interventions that boost the Treg cell response, such as mucosal immunotherapy, might lead to a restoration of immune tolerance to foods. Tolerance has been notoriously difficult to restore in animal disease models, but limited data from human trials suggest that tolerance (sustained nonresponsiveness) can be re-established in a subset of patients. Furthermore, studies on the natural history of food allergy indicate that spontaneous development of tolerance to foods over time is not uncommon. The current challenge is to understand the mechanisms responsible for restoration of natural or induced tolerance so that interventions can be developed to more successfully induce tolerance in the majority of patients with food allergy.

Recent advances in the understanding of egg allergens: basic, industrial, and clinical perspectives

The emergence of egg allergy has had both industrial and clinical implications. In industrialized countries, egg allergy accounts for one of the most prevalent food hypersensitivities, especially in children. Atopic dermatitis represents the most common clinical manifestation in infancy; however, the range of clinical signs is broad and encompasses life-threatening anaphylaxis. The dominant egg allergens are proteins and are mainly present in the egg white, for example, ovalbumin, ovomucoid, ovotransferrin, and lysozyme. However, egg yolk also displays low-level allergenicity, for example, alpha-livetin. Strict avoidance of the offending food remains the most common recommendation for egg-allergic individuals. Nevertheless, the omnipresence of egg-derived components in prepackaged or prepared foods makes it difficult. Therefore, more efficient preventive approaches are investigated to protect consumers from inadvertent exposure and ensuing adverse reactions. On the one hand, commercial kits have become readily available that allow for the detection of egg contaminants at trace levels. On the other hand, attempts to produce hypoallergenic egg-containing products through food-processing techniques have met with promising results, but the approach is limited due to its potentially undesirable effects on the unique functional and sensory attributes of egg proteins. Therefore, the development of preventive or curative strategies for egg allergy remains strongly warranted. Pilot studies have suggested that oral immunotherapy (IT) with raw or cooked preparations of egg may represent a safe alternative, immediately available to allergic subjects, but remains applicable to only nonanaphylactic patients. Due to the limitations of conventional IT, novel forms of immunotherapy are sought based on information obtained from the molecular characterization of major egg allergens. In the past decade, promising approaches to the treatment and prevention of egg allergy have been explored and include, among others, the production of hypoallergenic recombinant egg proteins, the development of customized peptides, and bacterial-mediated immunotherapy. Nonspecific approaches have also been evaluated, and preliminary trials with the use of probiotic bacteria have yielded encouraging results. The current understanding of egg allergens offers novel approaches toward the making of food products safe for human consumption and the development of efficient immunotherapeutic strategies.

T cell proliferation and cytokine responses to ovalbumin and ovomucoid detected in children with and without egg allergy

BACKGROUND

The specific T cell responses in egg allergy and resolution have not been fully elucidated.

OBJECTIVE

To characterize egg allergen-specific T cells of children with active and resolved egg allergy, in comparison with non-allergic controls.

METHOD

We studied children with active (n=35) or resolved (n=20) egg allergy determined by oral challenge, and non-allergic controls (n=15). Peripheral blood mononuclear cells were labelled with carboxyfluorescein succinimidyl ester (CFSE) and stimulated with ovalbumin (OVA), ovomucoid (OM) or tetanus toxoid. Flow cytometry was used to detect divided CD3+ CFSE(lo) cells that expressed intra-cytoplasmic IL-4 or IFN-gamma. The cell division index (CDI) was calculated as a measure of allergen-specific proliferation. Peanut-specific T cells of a subgroup of children who also had peanut allergy were also studied.

RESULTS

OVA-specific T cells were found in subjects with active (87%) or resolved (75%) egg allergy and in controls (67%), with a trend towards increased T cell proliferation in allergy. OM-induced weaker T cell responses than OVA, stimulating fewer responders (46% allergic, 50% resolved, 60% controls) and 10-fold less proliferation [CDI(OVA) 2.0 (median), 25.6 (maximum) vs. CDI(OM) 0.2 (median), 15.1 (maximum); P<0.01]. Both egg allergens induced significant IL-4+ (median 10%, range 1.4-58%) and IFN-gamma+ (median 28%, range 4.5-63%) cells in responders, including non-allergics. There were no significant differences in IFN-gamma+ or IL-4+ cells or in IFN-gamma/IL-4 ratios between groups. Peanut-specific T cell proliferation was significantly higher in peanut allergy [CDI(CPE) 16.5 (median), 24.8 (maximum)] compared with controls [CDI(CPE) 2.1 (median), 16.1 (maximum)] but cytokine profiles were not different. Tetanus-specific T cells were seen in 90% of the subjects, with no significant inter-group differences in responses.

CONCLUSION

Egg allergen-specific T cells are readily detected in all groups and not restricted to egg allergy. In contrast, peanut-specific proliferation was significantly higher in peanut allergy. This suggests that T cell responses in peanut and egg allergy may differ. We did not find T helper type 2-deviated cytokine responses in egg or peanut allergy.

T-cell epitopes of food allergens

During recent years, a great deal of research has focused on the identification of food allergens, their characterization at the molecular level, and the investigation of immunological mechanisms responsible for food hypersensitivity. Allergen-reactive T-helper 2 cells play a central role in the pathophysiology of allergic diseases. After activation with allergens, this subset of CD4(+) T-lymphocytes produces a spectrum of cytokines that induce high serum levels of immunoglobulin E and eosinophilia, which, in turn, mediate the clinical symptoms. Furthermore, T-helper 2 cells are present in target organs during the late response to allergen exposure. The analysis of the allergic T-cell response, including cytokine production and the identification of T-cell epitopes, provides important information on the characteristics of food allergens. Therefore, in vitro cultures of allergen-specific T-cells derived from peripheral blood or different target organs have been of indispensable help. Results obtained from such studies may not only contribute to the understanding of cellular mechanisms underlying different types of food allergy but also to the development of novel strategies for immunotherapy of food allergy.

Patterns of food allergen-specific cytokine production by T lymphocytes of children with multiple allergies

BACKGROUND

The contribution of different T cell subsets to the overall measured cytokine response to food allergens is largely unexplored.

METHOD

The patterns of cytokine production of peripheral blood-derived T cells after allergen stimulation were studied in 22 children with multiple food allergies and in 20 non-allergic children as controls, using flow cytometry.

RESULTS

Proportions of T cells of food-sensitized children spontaneously secreting IFN-gamma and IL-10 (without antigen stimulation) were lower than non-atopic children and adult controls (P<or=0.001). The proportions of IL-4-producing cells in vitro were significantly increased (P<or=0.04) and IFN-gamma-producing cells were significantly reduced (P<or=0.05) in sensitized children after incubation with and without dendritic cell presentation of peanut extract, beta-lactoglobulin and ovalbumin. The reverse pattern was found in non-sensitized children and adult controls. IL-4 secretion in allergic children to sensitizing allergens was mainly restricted to the CD4(+) CD45 RO(+) population while in non-atopic controls both CD4(+) and CD8(+) CD45 RO(+) cells produced mostly IFN-gamma. Food-specific IgE values did not correspond with cytokine responses but IL-4 production and IFN-gamma reduction relative to normal children were closely associated with total IgE levels.

CONCLUSION

Food-allergic children's IL-4 cytokine response to their relevant allergens is predominantly from a memory population of CD4(+) CD45 RO(+) cells, whereas IL-4 and IFN-gamma secretion of non-allergic controls was predominantly from mixed CD4(+) and CD8(+) CD45 RO(+) populations.

T lymphocytes and food allergy

Food allergy is a hypersensitivity reaction to normally harmless substances and involves humoral immune responses, mediated by immunoglobulin (IgE) synthesized by B lymphocytes, and cellular immune responses mediated by T lymphocytes. An IgE-mediated mechanism leads to clinical symptoms occurring immediately after food ingestion, e. g., "the oral allergy syndrome". For delayed reactions involving the gastrointestinal tract or the skin, the underlying immune mechanisms are less clear. In order to elucidate the cellular response to food allergens, human allergen-specific T cell cultures generated in vitro represent helpful tools. The majority of food allergen-specific CD4(+) T lymphocytes isolated from food-allergic individuals was found to synthesize high levels of IL-4 and IL-13, two cytokines required for initiation of IgE synthesis. Due to selective homing profiles, food-specific T cells seem also to be involved in defining the target organ of the allergic inflammation. Recent data provide evidence that in addition to IgE-mediated inflammation, food allergen-specific T lymphocytes may also cause inflammatory responses independently of IgE-mediated mechanisms.

T helper-2 immunity regulates bronchial hyperresponsiveness in eosinophil-associated gastrointestinal disease in mice

BACKGROUND & AIMS

Eosinophil-associated gastrointestinal diseases are frequently associated with extraintestinal features, including bronchopulmonary manifestations. The factors predisposing to bronchial hyperresponsiveness in eosinophil-associated gastrointestinal diseases are unknown. To elucidate the mechanistic link between eosinophil-associated gastrointestinal diseases and bronchial hyperresponsiveness, we used murine models of eosinophil-associated gastrointestinal diseases and eotaxin-1/transgene-induced eosinophil-associated gastrointestinal diseases.

METHODS

Mice were sensitized and orally challenged with ovalbumin-coated encapsulated particles to induce eosinophil-associated gastrointestinal disease, and bronchial responsiveness was examined. Furthermore, transgenic mice expressing eotaxin in the intestine (with the rat fatty acid-binding promoter) were used to specifically elucidate the contribution of this chemokine in eosinophil-associated gastrointestinal disease-associated bronchial hyperresponsiveness.

RESULTS

The induction of allergen-induced eosinophil-associated gastrointestinal disease was directly correlated with the development of bronchial hyperresponsiveness. The development of bronchial hyperresponsiveness in mice with allergen-induced eosinophil-associated gastrointestinal disease was dependent on eotaxin expression in the gastrointestinal tract. Expression of eotaxin in the gastrointestinal tract of transgenic mice was sufficient to promote bronchial hyperresponsiveness. Bronchial hyperresponsiveness was shown to be directly linked to the aberrant CD4(+) T helper 2 lymphocyte production of interleukin-13. It is interesting to note that transgenic expression of eotaxin was linked with enhanced T helper 2 lymphocyte/cytokine synthesis (interleukin-4, -5, and -13) and the production of mucosal immunoglobulin G1 in the gastrointestinal lumen. We also showed that eotaxin treatment of CD4(+) T cells enhanced interleukin-13 production in vitro.

CONCLUSIONS

These studies suggest that increased expression of eotaxin in the gastrointestinal compartment can lead to increased CD4(+) T cell-derived T helper 2 lymphocyte-cytokine production that drives aberrant immunophysiological responses in distant noninflamed mucosal tissue (the lung). These results provide a possible explanation for the altered lung function seen in some patients with inflammatory gastrointestinal disorders.

Localization of T cell epitope regions of chicken ovomucoid recognized by mice

We localized the T cell epitope regions of chicken ovomucoid (OVM), a potent egg allergen, with the overlapping pin-peptides covering the entire sequence of OVM and three strains of mice with different haplotypes. In C3H/He (H-2k) mice, the T cells recognized relatively broad regions on OVM; the dominant regions were 49-93 and 97-114 residues, and the subdominant regions were 7-21, 37-48, 94-96, 115-123 and 145-177 residues. In contrast, a more limited number of T cell epitope regions were localized in BALB/c (H-2d) and C57BL/6 (H-2b) mice. The T cells from BALB/c mice recognized 100-114 and 157-171 residues, and the T cells from C57BL/6 mice recognized only 157-180 residues. These results were confirmed by using peptides separately synthesized and purified on the putative epitope regions. The roles of the carbohydrate moieties and cysteine residues involved in the disulfide bridges of OVM were also examined, and we found that they were not important in recognition by the T cell/antigen presenting cell.

T lymphocytes in food allergy: overview of an intricate network of circulating and organ-resident cells

Although food hypersensitivity might be divided in IgE- and non-IgE mediated food allergy, there is a large body of evidence implicating T lymphocytes overall in the pathogenesis of food allergy. Priming of naive T cells will occur mainly in Peyer's patches (PP), where surface receptors (l-selectin, CCR7 and CXCR4) will help to initiate diapedesis of the cells to the submucosa. Various antigen-presenting cells (e.g. dendritic cells, M cells) will present food antigen-derived epitopes and initiate either non-responsiveness, or a food-mediated immune response. Food-specific memory T cells express various surface receptors such as the alpha4beta7-integrin, or the cutaneous lymphocyte antigen. It is speculated, that they might also express specific chemokine receptors (CCR4, CCR7 or CCR9). Organ-specific homing will be facilitated through the corresponding receptors (i.e. MAdCAM-1 in the gut, VCAM-1 or fibronectin in other mucosal organs, or E-selectin in the skin). Locally secreted chemokines might help to attract T cells through their corresponding chemokine receptors. Finally, potential T-cell directed therapeutic interventions (peptide-derived immunotherapy, DNA vaccination, or strategies preventing T cells from trafficking to target organs) are discussed.

Interaction among human leucocyte antigen-peptide-T cell receptor complexes in cow's milk allergy: the significance of human leucocyte antigen and T cell receptor-complementarity determining region 3 loops

BACKGROUND

Allergic individuals respond to only a few specific antigens, therefore allergic diseases are characterized by antigen specificity. Clarification of the mechanism of antigen specificity will lead to progress in the therapy of allergic diseases.

OBJECTIVES

The purpose of this study is to determine the specific association among T cell epitopes, antigen-presenting molecules and T cell receptor (TCR), and to determine the TCR usage in the pathogenesis of allergies using antigen-specific T cell clones (TCCs). The results can clarify the mechanism of the antigen specificity of allergic diseases, and provide new therapeutic possibilities using analogue peptides.

METHODS

Short-term T cell clones specific to beta-lactoglobulin (BLG) were established from peripheral blood mononuclear cells (PBMCs) collected from five patients allergic to cow's milk. We then identified the T cell epitopes and antigen-presenting molecules, and examined TCR usage. We also determined the sequence of the TCR-complementarity-determining region 3 (CDR3).

RESULTS

Six TCCs established from the five patients recognized three different peptides, and BLGp97-117 was recognized by four of the six TCCs. BLGp101-112 (KYLLFCMENSAE) was the core sequence in the fragment. Sequence analysis of TCR by the RT-PCR method revealed a marked heterogeneity in TCR usage, and similar amino acid sequences were recognized in the CDR3 region. Four of the six TCCs recognized BLG in association with human leucocyte antigen (HLA)-DRB1*0405 as antigen-presenting molecules.

CONCLUSION

We proposed the motif of the interaction between the HLA-DRB1*0405 allele and antigen peptide, and suggested that HLA-DRB1*0405 is an immunoregulatory gene product for T cell responses to BLG.

Cellular immune responses to ovalbumin and house dust mite in egg-allergic children

BACKGROUND

Although IgE-mediated food (egg) allergy is typically lost with age the underlying immune mechanisms are not understood, particularly in relation to the development of persistent IgE-mediated aeroallergen sensitivity.

METHODS

Lymphoproliferation and cytokine responses (IL-5, IL-10, IL-13 and IFN-gamma) to house dust mite (HDM) allergen and egg ovalbumin (OVA) were assessed using peripheral blood mononuclear cells (PBMC) from children aged 6 months to 5 years (n = 59) with acute IgE-mediated egg allergy (urticaria and angiedema or anaphylaxis), as confirmed by positive skin prick testing (SPT). Of these 46 had positive SPT on the day of blood collection and 13 had outgrown egg allergy (negative SPT and successful egg challenge). Where possible, responses were compared with previous data from nonallergic children of similar ages (n = 107).

RESULTS

Transient lymphoproliferative responses to OVA were seen in both egg-allergic and nonallergic children, but were more marked and more prolonged in egg-allergic children. Younger egg-allergic children (< 18 months) showed a mixed Th0 cytokine response to OVA, with readily detectable IFN-gamma, IL-5, IL-13 IL-10. Although IL-13 and IL-5 responses (OVA) correlated in younger egg-allergic children, there was a dissociation of these Th2 responses with age. Loss of clinical reactivity to egg was associated with almost complete loss of IL-5 responses and OVA-specific lymphoproliferation. Although IL-13 levels tended to be lower with age, this was not significant. Strong IFN-gamma and IL-10 responses to OVA persisted in older children after loss of OVA-specific lymphoproliferation. Lymphoproliferative responses to HDM also developed earlier in egg-allergic children compared with nonallergic children. Th1 (IFN-gamma) responses to HDM were largely below detection prior to 18 months of age, but increased significantly with age. In egg-allergic children Th2 (IL-5, IL-13) HDM responses also progressively increased with age. At 3 years of age almost all egg-allergic children had positive SPT to HDM and positive lymphoproliferative responses to HDM, with strong Th1 and Th2 (Th0) cytokine production.

CONCLUSIONS

IL-5 responses (rather than IL-13) responses most closely reflected clinical food allergy, with dissociation of IL-5 and IL-13 responses in older and egg-tolerant children. In this population, food and aeroallergen sensitivity was not associated with inability to produce IFN-gamma, but rather with mixed Th2 and Th1 (Th0) responses. Strong IL-10 and IFN-gamma responses where associated with the development of tolerance, suggesting persistent 'regulatory' populations of OVA-specific T cells, rather than clonal deletion of OVA responsive T-cells.

Identification of beta-lactoglobulin-derived peptides and class II HLA molecules recognized by T cells from patients with milk allergy

BACKGROUND

Cow's milk allergy impairs the health and development of many infants since it deprives them of adequate nutrition. Cow's milk fractions contain many allergens, and beta-lactoglobulin (BLG) is one of the major allergens.

OBJECTIVE

The purpose of this study was to determine T cell epitopes, antigen-presenting molecules and cytokine production by T cells in relation to BLG. The results can provide new therapeutic possibilities of using analogue peptides of BLG for infants with cow's milk allergy.

METHODS

Using a mixture of a panel of overlapping synthetic peptides that cover the entire BLG molecule, we established polyclonal BLG-specific short-term T cell lines and clones from peripheral blood mononuclear cells of four patients with allergy to cow's milk carrying most of the common human leucocyte antigen (HLA) haplotypes seen in the Japanese population. We then identified the T cell epitopes and antigen-presenting molecules, and measured the production of cytokines interleukin (IL)-4, IL-5 and interferon-gamma in the culture supernatants.

RESULTS

The T cell lines established from the four patients responded to seven different peptides. Three of the peptides stimulated the T cells of two donors, regardless of the HLA types. The patterns of inhibition of the proliferative responses of the cell lines by anti-HLA class II antibodies were heterogeneous; three were mainly inhibited by anti-HLA-DR mAbs, and the other was inhibited by anti-HLA-DQ mAbs. High levels of IL-5 were produced by these T cell lines.

CONCLUSIONS

Patients' T cells recognized BLG in association with a variety of HLA-DR or -DQ as antigen-presenting molecules. Although some peptides did have a more potent T cell stimulatory activity than others, the T cell receptor ligands formed with the BLG molecule are heterogeneous. Peptides for the desensitization of T cells of the patients with cow's milk allergy need to be designed keeping in mind the different requirements in different ethnic groups.

Novel B and T cell epitopes of chicken ovomucoid (Gal d 1) induce T cell secretion of IL-6, IL-13, and IFN-gamma

BACKGROUND

Chicken ovomucoid (OM, Gal d 1) has an important role in the pathogenesis of IgE-mediated allergic reactions to hen's egg white.

OBJECTIVES

The purpose of this study was to clarify the mechanisms of T cell recognition of ovomucoid using intact OM and chemically modified, characterized and homogeneous solid phase synthetic peptides covering the whole molecule.

METHODS

Eighteen overlapping peptides were prepared by solid phase F-moc polyamide peptide synthesis (SPPS), characterized and high-pressure liquid chromatography (HPLC) purified. The peptides, together with intact, denatured and oxidized OM, were used to stimulate patient-derived cell cultures for mapping T cell epitopes. Proliferation responses, T cell phenotype and cytokine secretion using peripheral blood mononuclear cells (PBMC) from eight individuals and T cell lines (TCL) derived from six hen's egg-allergic patients, were examined. In addition, intact, denatured, oxidized and deglycosylated OM, as well as the peptides solely or with their keyhole limpet haemocyanin (KLH) complexes, were tested. For locating IgE and IgG B cell epitopes, seven egg-allergic patient sera and three OM-polyclonal sera were used. Healthy non-allergic individuals were included as controls.

RESULTS

Seven peptides were recognized by specific IgE, while OM-specific TCL recognized 10 peptides. Six of the OM peptides were commonly recognized both by patient S-IgE and blood-derived TCL. Among those, one novel epitope, peptide OM 61-74, had the ability to bind IgE. Another peptide, OM 101-114, was recognized by IgE and IgG sera, but not by any of the TCLs. In contrast, the peptides OM 41-56, OM 71-84, OM 131-144 and OM 171-186 were exclusively T cell epitopes with no affinity to specific antibodies. Abundant TCL secretion of IFN-gamma, IL-6, IL-4, IL-13, IL-10 and TNF-alpha in response to OM stimulation indicates the contribution of Th2 as well as Th1/Th0 CD4+ cell subsets. For allergic patients moderate amounts of IFN-gamma, IL-13, and high amounts of IL-6, were secreted in response to TCL stimulation by OM peptides. High amounts of IL-6 were secreted in response to all molecular forms of OM (intact-, modified-OM and the peptides 71-84 and 51-64) when TCLs from two non-allergic donors were used.

CONCLUSIONS

One novel B cell epitope (OM 61-74) and 10 T cell epitopes have been identified. The most reactive epitopes of the OM molecule comprise the motifs 1-14 to 71-84, the overlapping peptide-pairs OM 121-134 and OM 131-144 and peptides OM 161-174 and 171-186. Peptides OM 1-14 and 171-186 are the only ones capable of inducing IL-4 secretion. Only one peptide (OM 11-24) induces IL-10 secretion. Those peptides recognized as both T and B cell epitopes or only T cell epitopes, have the potential to induce T cell secretion of moderate to high amounts of IL-13, IFN-gamma and particularly IL-6.

Differences in antigen-specific T-cell responses between infants with atopic dermatitis with and without cow's milk allergy: relevance of TH2 cytokines

BACKGROUND

Cow's milk is the most important food antigen in infancy and may lead to acute cutaneous symptoms and atopic dermatitis (AD). The role of circulating allergen-specific T cells in the pathogenesis of food-allergic skin symptoms is still under investigation.

OBJECTIVE

This study was designed to analyze the cow's milk protein (CMP)-specific T-cell response at the clonal level in infants with AD and cow's milk allergy (CMA) in comparison with infants with AD without CMA.

METHODS

We used an antigen-specific culturing system with autologous B cells as antigen-presenting cells to establish CMP-specific T-cell clones derived from PBMCs in infants with AD. T-cell reactivity, measured by using a lymphocyte stimulation test, and cytokine production, measured by using ELISA, was compared between infants with AD with and without CMA.

RESULTS

Both infants with and without allergy to cow's milk had a CMP-specific T helper cell response directed against the major proteins in milk. Analysis of antigen-specific cytokine production showed that this response was T(H)2 skewed in infants with CMA, with production of high levels of IL-4, IL-5, and IL-13. In contrast, infants without CMA had a T(H)1-skewed response, with high levels of IFN-gamma and low levels of IL-4, IL-5, and IL-13.

CONCLUSION

These data confirm for the first time at the clonal level that food allergy in infants with AD is associated with production of T(H)2 cytokines by circulating antigen-specific CD4(+) T cells, whereas tolerance to food antigens is associated with low levels of these cytokines. This suggests a key role for the T helper cell-derived T(H)2 cytokines in food allergy-related skin symptoms.

Clinical relevance of food additives in adult patients with atopic dermatitis

BACKGROUND

Adverse reactions to food play an important role in the pathogenesis of atopic dermatitis (AD). In infancy and childhood, food allergies are observed in up to 30%, whereas nonallergic hypersensitivity reactions (pseudoallergic reactions) towards food additives have been reported to occur between 2 and 7%. By contrast, sensitizations towards food allergens are rarely of clinical relevance in adults and little data is available on nonallergic hypersensitivity reactions. To date the role of pseudoallergic reactions as an aggravating factor in AD of adult patients remains controversial. However, many adult patients report on food-related aggravation of the disease and nonallergic hypersensitivity reactions have been incriminated repeatedly.

OBJECTIVE

To elucidate the relevance of food additives in adult patients suffering from AD.

METHODS

Fifty patients were monitored over 4 weeks under regular diet followed by 6 weeks of a diet omitting known pseudoallergens. Skin status of patients was assessed every 2 weeks by a standardized scoring, and serum eosinophilic cationic protein (ECP) was determined before and after diet.

RESULTS

Nine of fifty patients dropped out, 26 showed a significant improvement of the Costa-score by 57%. In 23/26 patients a corresponding reduction of serum ECP level by 52% on average was determined. Responder patients (24/26) were orally challenged with food rich in pseudoallergens followed by double-blind exposure to food additives (n = 15). A worsening of the eczema was seen in 19/24 patients after intake of pseudoallergen-rich food and in 6/15 patients after exposure to food additives.

CONCLUSION

These results indicate that a subgroup of adult patients with AD clinically improve on low-pseudoallergen diet but only a small subgroup respond to oral provocation with food additives.

The mucosal adhesion receptor alpha4beta7 integrin is selectively increased in lymphocytes stimulated with beta-lactoglobulin in children allergic to cow's milk

BACKGROUND

It has been shown in mice that the integrin alpha4beta7 directs the migration of memory T cells into the gut-associated lymphoid tissue. However, little is known about T-cell homing mechanisms in children with food allergies.

OBJECTIVE

We investigated the expression of this and other integrins in children with different manifestations of cow's milk allergy (urticaria, atopic dermatitis, and wheezing).

METHODS

PBMCs were stimulated with beta-lactoglobulin, 1 of the major allergenic proteins in cow's milk, and tetanus toxoid. Integrin expression was studied by flow cytometric analysis after 1 week of culture.

RESULTS

We found significantly higher expression of the alpha4beta7 integrin in cells from patients compared with control subjects with no allergies (P =. 005) when beta-lactoglobulin was used to stimulate the cells. alpha4beta7 integrin was also expressed at significantly higher levels in beta-lactoglobulin-stimulated cells than in tetanus toxoid-stimulated cells (P =.005). The alphaEbeta7 and the alpha4beta1 integrins were not upregulated by allergen stimulation. Most alpha4beta7 integrin-expressing cells were identified as CD4(+) T cells.

CONCLUSION

These results show that alpha4beta7 integrin expression after stimulation with beta-lactoglobulin correlates with the presumptive site of cow's milk sensitization (ie, the gut-associated lymphoid tissue but not with the site of symptoms of cow's milk allergy).