Sensitization to Malassezia in children with atopic dermatitis combined with food allergy.

BACKGROUND: The yeast Malassezia belongs to our normal cutaneous flora, but is capable of sensitizing individuals with atopic dermatitis (AD). Our objective was to investigate the prevalence of sensitization to Malassezia with a 10-yr follow-up among children suffering from AD combined with food allergy (FA) in relation to the extent of AD in infancy. METHODS: One hundred and eighty seven infants diagnosed with AD and milk/wheat allergy before 1 yr of age were included in the study. The area of AD was estimated from patient records of the first visit and measured with SCORAD at the 10-yr follow-up. Specific IgE against Malassezia was determined with ImmunoCAP™ at 11 yr of age. RESULTS: In infancy, 24 children (13%) were allergic to milk, 71 (38%) to wheat, and 92 (49%) to both milk and wheat, and 94 (50%) children had mild, 57 (30%) moderate and 36 (19%) severe AD. At the 10-yr follow-up visit, 19 (10%) of the children had ongoing milk and/or wheat allergy; 147 children (79%) had mild AD and 30 (16%) had SCORAD index of 0. Specific IgE against Malassezia mix was positive (≥0.35 kU/l) in 27% and specific IgE against M. sympodialis in 20% of the 187 children. The area of AD in infancy was associated with a greater risk of having allergen-specific IgE to Malassezia at the 10-yr follow-up. The risk ratio for FA was 3.11 (95% CI: 2.05-4.72; p < 0.001) if specific IgE to Malassezia was positive. CONCLUSIONS: Infants with severe AD and FA seem to have a greater risk of becoming sensitized to Malassezia during a 10-yr follow-up.

Wheat omega-5 gliadin is a major allergen in children with immediate allergy to ingested wheat.

BACKGROUND: Sensitization to wheat by ingestion can lead to food allergy symptoms and wheat-dependent, exercise-induced anaphylaxis. Sensitization by inhalation causes bakers' asthma and rhinitis. Wheat allergens have been characterized at the molecular level in bakers' asthma and in wheat-dependent, exercise-induced anaphylaxis, in which omega-5 gliadin (Tri a 19) is a major allergen. However, little information is available regarding allergens responsible for hypersensitivity reactions to ingested wheat in children. OBJECTIVE: The aim of this study was to examine whether children with allergy to ingested wheat have IgE antibodies to omega-5 gliadin. METHODS: Sera were obtained from 40 children (mean age, 2.5 years; range, 0.7-8.2 years) with suspected wheat allergy who presented with atopic dermatitis and/or gastrointestinal and/or respiratory symptoms. Wheat allergy was diagnosed with open or double-blinded, placebo-controlled oral wheat challenge. Wheat omega-5 gliadin was purified by reversed-phase chromatography, and serum IgE antibodies to omega-5 gliadin were measured by means of ELISA. In vivo reactivity was studied by skin prick testing. Control sera were obtained from 22 children with no evidence of food allergies. RESULTS: In oral wheat challenge, 19 children (48%) reacted with immediate and 8 children (20%) with delayed hypersensitivity symptoms. Sixteen (84%) of the children with immediate symptoms had IgE antibodies to purified omega-5 gliadin in ELISA. In contrast, IgE antibodies to omega-5 gliadin were not detected in any of the children with delayed or negative challenge test results or in the control children. The diagnostic specificity and positive predictive value of omega-5 gliadin ELISA were each 100% for immediate challenge reactions. Skin prick testing with omega-5 gliadin was positive in 6 of 7 children with immediate challenge symptoms and negative in 2 children with delayed challenge symptoms. CONCLUSION: The results of this study show that omega-5 gliadin is a significant allergen in young children with immediate allergic reactions to ingested wheat. IgE testing with omega-5 gliadin could be used to reduce the need for oral wheat challenges in children.

Late onset reactions to oral food challenge are linked to low serum interleukin-10 concentrations in patients with atopic dermatitis and food allergy.

BACKGROUND: Aberrant cytokine production in vitro has been associated with atopic disease. No study has as yet been made of the circulating cytokine profiles in atopic patients with food allergy in response to oral allergen challenge. OBJECTIVE: To assess the effect of oral allergen challenge on the serum cytokine concentrations in patients with atopic dermatitis and food allergy. METHODS: Serum concentrations of interleukin (IL)-10, transforming growth factor beta 1, IL-1ra, IL-6, IL-5, IL-4 and interferon (IFN)-gamma were measured before and after double-blind, placebo-controlled food challenges (DBPCFC) (n = 73). Before DBPCFC, combined skin prick and patch testing was performed for cow milk, egg, soybean and cereals, and production of IFNgamma, IL-4, IL-10 and tumour necrosis factor alpha (TNFalpha) was determined in supernatants of cultures of peripheral blood mononuclear cells (PBMCs) stimulated by cow milk. RESULTS: The oral food challenge triggered immediate onset exanthematous reactions in 22 cases and late onset eczematous reactions in 29. The late-reacting cases had more positive skin patch test and negative skin prick test reactivities with allergenic food, and they had lower serum IL10 concentrations than immediate-reacting cases. In challenge-positive cases, IL-10 concentrations increased from 2.9 (0.1-5.04) pg/mL to 3. 9 (1.2-8.3) pg/mL in response to DBPCFC, P = 0.05, median (interquartile ranges), but not in those tolerant to cow milk. PBMCs of patients with cow milk allergy but not of those tolerant to cow milk generated TNFalpha in response to cow milk in vitro. CONCLUSION: These results indicate that oral allergen challenge in atopic patients with food allergy triggers systemic release of IL-10. Patients with late onset reactions were found to have lower serum IL-10 concentrations than their immediate-reacting counterparts. Considering that IL-10 is an inhibitory cytokine of delayed-type hypersensitivity, low IL-10 in late-reacting patients may explain the high frequency of their positive skin patch tests combined with negative skin prick tests.

Differences in skin-prick and patch-test reactivity are related to the heterogeneity of atopic eczema in infants.

Current data indicate an obvious relation between food allergy and atopic eczema in infants. However, diagnostic methods for food allergy need to be supplemented. The objective was to study the relevance of food patch testing in the detection of food allergy in correlation with oral food challenge and skin prick tests in atopic infants. Infants with atopic eczema (n = 113) aged 2-24 months were studied. Each patient was subjected to double-blind, placebo-controlled, or open cow's milk challenge, and skin prick and patch tests. Polysensitization, as judged from skin test results, was common in patients with atopic eczema (79/113). Cow's milk challenge was positive in 54/113 infants; reactions were immediate in 36/54 and delayed in 18/54. Immediate-type reactions were associated with skin prick test positivity and delayed reactions with patch test positivity. Altogether 26% of the cow's milk-allergic infants were detected by patch testing only. Patch testing improved the accuracy of skin testing in the diagnosis of food allergy in infants with atopic eczema, but it needs to be standardized. Polysensitization appears to be more common than generally believed among infants with atopic eczema.