Simultaneous quantification of specific food allergen proteins using a fluorescent multiplex array

The aim was to develop a fluorescent multiplex array for simultaneously measuring regulated food allergens using specific allergen protein molecules from peanut, tree nut, cow's milk, egg, soy, fish, shellfish, sesame, mustard and celery. Microspheres coupled to specific monoclonal antibodies were used for allergen detection, with purified allergens as reference standards.Standard curves for 17 allergens covered a 5-log dynamic range. Intra- and inter-assay acceptance criteria were within 70-130% recovery and a CV of ≤15%. Food reference materials contained high levels of their respective major allergens (2000-175,000 µg/g), Similar high allergen levels were found in 10 selected foods analysed using a 9-plex array. Egg, milk, peanut, hazelnut and walnut allergens were detectable in chocolate bars with incurred allergens at 3, 10, 30, and 100 ppm. The multiplex array is an efficient tool for measuring specific food allergens, with applications for risk assessment and standardization of therapeutic products for food allergy.

Bos d 11 in baked milk poses a risk for adverse reactions in milk-allergic patients

BACKGROUND

Patients are commonly challenged with foods containing baked milk, for example muffins, yet little is known about the specific allergen content of muffins used in milk challenges or of the effect that baking has on allergenicity.

OBJECTIVE

Our objective was to compare the levels of major milk allergens in uncooked and baked muffins using monoclonal immunoassays and IgE antibody binding before and after baking.

METHODS

Uncooked and baked muffins were prepared using recipes from Mount Sinai and Imperial College. Allergen levels were compared by ELISA for Bos d 5 (β-lactoglobulin) and Bos d 11 (β-casein). IgE reactivity was assessed using sera from milk-sensitized donors in direct binding and inhibition ELISA.

RESULTS

Bos d 5 was reduced from 680 µg/g in uncooked muffin mix to 0.17 µg/g in baked muffins, representing a >99% decrease after baking. Conversely, Bos d 11 levels in baked muffin remained high and only decreased by 30% from a mean of 4249 µg/g in uncooked muffin mix to 2961 µg/g when baked (~181 mg Bos d 11 per muffin). Baked muffins retained ~70% of the IgE binding to uncooked muffin mix. Baked muffin extract inhibited IgE binding to uncooked muffin mix by up to 80%, demonstrating retention of in vitro IgE reactivity.

CONCLUSIONS AND CLINICAL RELEVANCE

High levels of Bos d 11 in baked muffins pose a risk for adverse reactions, especially in patients who have high anti-casein IgE antibodies.

Innate Immunity Induced by the Major Allergen Alt a 1 From the Fungus Alternaria Is Dependent Upon Toll-Like Receptors 2/4 in Human Lung Epithelial Cells

Allergens are molecules that elicit a hypersensitive inflammatory response in sensitized individuals and are derived from a variety of sources. Alt a 1 is the most clinically important secreted allergen of the ubiquitous fungus, Alternaria. It has been shown to be a major allergen causing IgE-mediated allergic response in the vast majority of Alternaria-sensitized individuals. However, no studies have been conducted in regards to the innate immune eliciting activities of this clinically relevant protein. In this study, recombinant Alt a 1 was produced, purified, labeled, and incubated with BEAS-2B, NHBE, and DHBE human lung epithelial cells. Alt a 1 elicited strong induction of IL-8, MCP-1, and Gro-a/b/g. Using gene-specific siRNAs, blocking antibodies, and chemical inhibitors such as LPS-RS, it was determined that Alt a 1-induced immune responses were dependent upon toll-like receptors (TLRs) 2 and 4, and the adaptor proteins MYD88 and TIRAP. Studies utilizing human embryonic kidney cells engineered to express single receptors on the cell surface such as TLRs, further confirmed that Alt a 1-induced innate immunity is dependent upon TLR4 and to a lesser extent TLR2.

Arsenic and other trace elements in two catfish species from Paranaguá Estuarine Complex, Paraná, Brazil

Concentrations of arsenic and four additional trace elements (Cu, Cr, Ni, and Zn) were determined by inductively coupled plasma-optical emission spectrometry in the muscular tissue of the yellow catfish (Cathorops spixii) and the urutu catfish (Genidens genidens) from Paranaguá Estuarine Complex, Brazil (PEC). The PEC can be characterized by an environment of high ecological and economic importance in which preserved areas of rainforest and mangroves coexist with urban activities as ports and industries. The average concentrations (in milligram per kilogram dry weight) of elements in the muscle tissue of C. spixii are as follows: Zn (31), As (17), Cu (1.17), Cr (0.62), and Ni (0.28). Similar concentrations could be found in G. genidens with exception of As: Zn (36), As (4.78), Cu (1.14), Cr (0.51), and Ni (0.14). Fish from the geographic northern rural region (Guaraqueçaba-Benito) display higher As concentrations in the muscle tissues than fish found in the south-western (urban) part of the PEC. An international comparison of muscle tissue concentrations of trace elements in fish was made. Except for Ni in C. spixii, a tendency of decrease in element concentration with increasing size (age) of the fish could be observed. According to the National Health Surveillance Agency of Brazil, levels of Cr and As exceeded the permissible limits for seafood. An estimation of the provisional tolerable weekly intake of As was calculated with 109 % for C. spixii and with 29 % for G. genidens.

Purified Natural Ara h 6: An Important Marker for IgE Responses to Peanut (177.15)

Ara h 6 has a reported seroprevalence similar to Ara h 2, a major peanut allergen. Both allergens have a similar molecular weight (14.5kD - Ara h 6; 17-18kD - Ara h 2) and share 55% identity in their amino acid sequences. Thus, it has been difficult to obtain natural Ara h 6 (nAra h 6) free of Ara h 2. Our study compares the IgE antibody reactivity of highly purified nAra h 6 to a natural Ara h 6 reference reagent (nAra h 6-R), recombinant Ara h 6 (rAra h 6) and natural Ara h 2 (nAra h 2). SDS-PAGE of the highly purified allergen revealed a single 14.5kD band and the identity of Ara h 6 was confirmed by tandem mass spectrometry (LC/MS-MS). The purified nAra h 6 contained <0.005% traces of nAra h 2 as assessed by ELISA. Natural Ara h 6 had a lower biological activity in basophil histamine release assays than nAra h 2. Chimeric ELISA showed that 70 and 75% of peanut allergic patients (n=57) had specific-IgE to nAra h 2 and nAra h 6 respectively. Natural Ara h 6-R and rAra h 6 displayed similar IgE antibody reactivity when compared to the nAra h 6. In conclusion, Ara h 6 is a major peanut allergen, with comparable immunoreactivity to Ara h 2. The highly purified Ara h 6, free of Ara h 2, will be useful for diagnostic IgE antibody assays, and for molecular and cellular studies to further investigate the immunological mechanisms of peanut allergy.