C.A.F.M. Bruijnzeel-Koomen

Skin-derived aeroallergen-specific T-cell clones of Th2 phenotype in patients with atopic dermatitis

T-cell lines have been derived from aeroallergen-induced eczematous patch test sites of patients with atopic dermatitis (AD). Biopsy specimens were obtained 24 hours after allergen application to the skin, and only in vivo-activated T cells were propagated. From one patient, the T-cell lines were subcloned at 0.3 cells per well. With allergen-induced interleukin (IL) production, all clones tested (n = 13) were found to be specific for the allergen, producing IL-4 and granulocyte-macrophage-colony-stimulating factor. No IL-2 or interferon-gamma was found. The allergen-specific proliferative response of these clones, although the response was dependent on exogenous IL-2 or IL-4, also proved that all clones were allergen specific. Under optimal stimulation (aCD3 plus phorbol myristate acetate), 15% of the clones appeared to be of Th0 phenotype and 70% of Th2 phenotype. In 15% of the clones, IL-4 was produced in the absence of IL-2, IL-5, or interferon-gamma. Supernatants of all clones tested induced IgE production by B cells from normal non-atopic donors. The T-cell lines of the other patient demonstrated similar results; allergen-specific proliferation was dependent on exogenous IL-2 or IL-4 and stimulation with aCD3 plus phorbol myristate acetate demonstrated that the T cells in these lines were of the Th2 phenotype. In conclusion, our data reveal that, in AD, percutaneous sensitization to aeroallergens may occur and indicate that allergen-specific Th2 type T cells may be responsible for the high levels of (specific) IgE found in 80% of patients with AD.

Quantification of major peanut allergens Ara h 1 and Ara h 2 in the peanut varieties Runner, Spanish, Virginia, and Valencia, bred in different parts of the world

Background:u2002The serology of peanut allergy seems to be different in various parts of the world. We analyzed the composition of 13 samples of three varieties of peanut in order to compare their allergenic nature.

Children with peanut allergy recognize predominantly Ara h2 and Ara h6, which remains stable over time

Background In peanut‐allergic adults, IgE is mainly directed to Ara h1 and Ara h2. More recently, a role for Ara h6 has been suggested. In contrast to adults, IgE in children can fluctuate over time. Therefore, children may have a more dynamic reactivity to peanut.

Probiotics Have a Different Immunomodulatory Potential in vitro versus ex vivo upon Oral Administration in Children with Food Allergy

Background: Previous studies suggest that administration of probiotics in vitro can stimulate regulatory and Th1 immune responses. We studied both the in vitro immunological effects of probiotics and the ex vivo immunological effects after oral administration of probiotics in children with food allergy, a Th2-mediated disease. Methods: Thirteen children were enrolled. Probiotics (n = 7) or placebo (n = 6) were orally administered during 3 months. At baseline and after 1 and 3 months, peripheral blood mononuclear cells were stimulated with crude peanut extract, anti-CD3, or anti-CD40 and IL-4 in the presence (in vitro response) or absence (ex vivo response) of probiotics. The proliferation and production of IFN-γ, IL-5, IL-13, IL-10, TNF-α, IL-6 and IgE were analyzed. Sensitization to peanut, cow’s milk and hen’s egg was determined before and after treatment. Results: The in vitro addition of probiotics to peripheral blood mononuclear cell cultures resulted in enhanced proliferation and production of IFN-γ, IL-10 and TNF-α. After oral treatment, proliferation in the presence of probiotics increased, whereas in vitro IgE production decreased in the probiotics group compared to baseline. The ex vivo production of IL-10, TNF-α and IL-6 tended to decrease. Th1 and Th2 cytokines were not altered. Sensitization remained unchanged. Conclusion: Probiotics enhanced the production of Th1 and regulatory cytokines in vitro. Oral administration of probiotics resulted in a slightly decreased ex vivo production of IL-10, TNF-α and IL-6. This indicates that probiotics have a different potential to modulate the immune response in vitro versus ex vivo.

T cell responses to major peanut allergens in children with and without peanut allergy

Background T cell responses involved in peanut allergy are poorly understood.

Role of Human Leucocyte Antigen DQ in the Presentation of T Cell Epitopes in the Major Cow’s Milk Allergen αs1-Casein

Background: Little is known about the association between human leucocyte antigen (HLA) and cow’s milk allergy (CMA). The aim of the present study was to determine the HLA restriction of T cell clones (TCCs) specific to αs1-casein, the most abundant milk protein, and to study possible HLA class II allele associations with CMA. Methods: αs1-Casein-specific TCCs were derived from 6 children with CMA, 9 atopic children without CMA and 5 non-atopic children. T cell epitope specificity was defined by stimulation with overlapping peptides, spanning the αs1-casein molecule. HLA restriction was determined in proliferation assays using antibodies blocking either HLA-DP, HLA-DQ or HLA-DR. HLA genotyping was performed in 32 subjects with CMA, 23 atopic and 22 non-atopic individuals. Results: Ten TCCs were restricted to HLA-DQ, 6 TCCs to HLA-DR and 4 TCCs to HLA-DP. The sequence in αs1-casein that was most immunogenic to T cells from children with CMA contained T cell epitopes restricted to DQB1*0201, DPB1*0401 and DRB1*1501. The DQB1*0501 allele frequency was lower in children with CMA than in non-atopic children, but this difference could not be confirmed in an additional group of subjects with and without CMA. Conclusions: HLA-DQ plays a substantial role in the presentation of T cell epitopes in αs1-casein. However, HLA class II allele frequencies do not show major differences between cow’s milk allergic, atopic and non-atopic subjects. T cell epitopes in the most immunogenic region are presented by various abundantly present HLA genotypes. Therefore, this sequence may be a suitable target for peptide immunotherapy.

Anaphylactic versus Mild Reactions to Hazelnut and Apple in a Birch-Endemic Area: Different Sensitization Profiles?

Background: Hazelnut and apple are common causes of food allergy in Europe. In northern Europe, symptoms are usually mild and associated with cross-reactivity to the birch pollen allergen, Bet v 1. In the Mediterranean area, symptoms are more frequently severe and associated with sensitization to lipid transfer protein (LTP). This study compared patients with anaphylactic versus mild reactions to hazelnut and apple in The Netherlands, a birch-endemic area, with respect to sensitization to Bet v 1-homologues (i.e. PR10-proteins) and LTP. Methods: Twenty-one patients fulfilling the criteria for anaphylaxis and 21 with only mild symptoms (oral allergy) to hazelnut and/or apple were recruited. Specific immunoglobulin E to birch pollen, apple, hazelnut and PR10-proteins (rBet v 1, rPru p 1, rMal d 1 and rCor a 1) and recombinant LTP (rPru p 3 and rCor a 8) was measured by ImmunoCAP. Results: Both mild and anaphylactic apple-allergic patients were sensitized to PR10-proteins, whereas only 1/7 of the mild and none of the anaphylactic apple-allergic patients was sensitized to LTP. In contrast, anaphylactic hazelnut-allergic patients displayed no such clear sensitization pattern: some were sensitized to both PR10-proteins and hazelnut LTP (1/9), and others to only LTP (2/9) or to only PR10-proteins (4/9) or to neither PR10-proteins nor LTP (2/9). Conclusion: This study shows that in a birch-endemic area, the sensitization profile to PR10-proteins and LTP in anaphylactic patients may differ between different plant foods. In this patient group, anaphylaxis to hazelnut can be LTP-associated, whereas anaphylaxis to apple is not.

Suboptimal management of acute food‐allergic reactions by patients, emergency departments and general practitioners

Suboptimal food allergy management by patients and doctors.

Role of Langerhans Cells in Atopic Disease

So far, the role of antigen-presenting cells in atopic disorders has been underestimated. Recent observations, made in the skin of patients with atopic dermatitis and in the nasal mucosa of patients with allergic rhinitis suggest that Langerhans cells, being tissue-specific dendritic cells with potent antigen-presenting capacity, play an important role in the allergic inflammatory response. Evidence is presented that Langerhans cells even play a crucial role in directing the type of the allergic reaction mechanism.

Skin eosinophilia in patients with allergic asthma, patients with nonallergic asthma, and healthy controls: II: 20-hydroxy-leukotriene B4 is a potent in vivo and in vitro eosinophil chemotactic factor in nonallergic asthma

BACKGROUNDnIn allergic and nonallergic asthma, eosinophils play an important effector role. However, because the pathogenesis of these types of asthma seems different, the mechanisms responsible for the tissue mobilization of those cells may be different. The in vivo and in vitro migratory response of eosinophils from patients with allergic and nonallergic asthma toward 20-hydroxy-leukotriene B4 (20-OH-LTB4), which is reported here, illustrates this.nnnMETHODSnBy means of the Rebuck skin window technique the in vivo skin mobilizing capacity of intracutaneously applied buffer, LTB4, and 20-hydroxy (OH)-LTB4 was evaluated in healthy subjects (n = 6), subjects with allergic asthma (n = 14), and subjects with nonallergic asthma (n = 17). Also the in vitro chemotactic responsiveness of eosinophils from the circulation of both patient groups (both n = 8) toward buffer, LTB4, and 20-OH-LTB4 were tested by use of a microchemotaxis chamber technique.nnnRESULTSnAlthough none of the substances were capable of inducing macroscopic observable skin reactions, intracutaneously applied 20-OH-LTB4 had an almost similar capacity to mobilize eosinophils in the skin of the subjects with nonallergic asthma as allergens had in subjects with allergic asthma. In 92% of the tested subjects with nonallergic asthma significant skin eosinophilia was observed. By contrast, LTB4 did not induce significant skin eosinophilia in both patient groups compared with buffer solution. This in vivo eosinophil mobilizing capacity of 20-OH-LTB4 in subjects with nonallergic asthma was confirmed by in vitro chemotaxis studies. Dose ranges of both LTB4 and 20-OH-LTB4 proved to be potent chemoattractants for eosinophils from patients with nonallergic asthma, but not for those of healthy subjects and those with allergic asthma.nnnCONCLUSIONSnOur results indicate that 20-OH-LTB4 may be involved in the tissue mobilization of eosinophils in nonallergic asthma and that in vitro 20-OH-LTB4 (and LTB4) may act as potent chemotactic factors on eosinophils from those patients.