A comparative study of the allergenic potency of wild-type and glyphosate-tolerant gene-modified soybean cultivars.

A large proportion of soybean cultivars grown in the USA are now genetically modified varieties and concern has been raised about the safety of these products for consumers. A study of the impact on allergenic potency in soybeans, comparable except for the newly introduced gene (CP4 EPSPS), was performed using soybean-sensitized patients. The allergenicity of 18 different (10 GM and 8 WT) soybean extracts was examined blindly by the following three methods: A) Sera from patients with specific IgE against soybean were used to determine concentrations inducing 50% RAST inhibition; B) Histamine release induced by the extracts was examined using blood from sensitized patients; C) SPT was performed on sensitized patients with all 18 extracts. All three methods showed variations in the allergenic potency between the individual extracts but allergenic potential was not affected by presence of the transgene. By using standard in vitro methods and SPT for determination of allergenicity we were not able to detect any significant difference in the allergenic potency between GM and WT soybeans.

Evaluation of the potential allergenicity of the enzyme microbial transglutaminase using the 2001 FAO/WHO Decision Tree.

All novel proteins must be assessed for their potential allergenicity before they are introduced into the food market. One method to achieve this is the 2001 FAO/WHO Decision Tree recommended for evaluation of proteins from genetically modified organisms (GMOs). It was the aim of this study to investigate the allergenicity of microbial transglutaminase (m-TG) from Streptoverticillium mobaraense. Amino acid sequence similarity to known allergens, pepsin resistance, and detection of protein binding to specific serum immunoglobulin E (IgE) (RAST) have been evaluated as recommended by the decision tree. Allergenicity in the source material was thought unlikely, since no IgE-mediated allergy to any bacteria has been reported. m-TG is fully degraded after 5 min of pepsin treatment. A database search showed that the enzyme has no homology with known allergens, down to a match of six contiguous amino acids, which meets the requirements of the decision tree. However, there is a match at the five contiguous amino acid level to the major codfish allergen Gad c1. The potential cross reactivity between m-TG and Gad c1 was investigated in RAST using sera from 25 documented cod-allergic patients and an extract of raw codfish. No binding between patient IgE and m-TG was observed. It can be concluded that no safety concerns with regard to the allergenic potential of m-TG were identified.

Allergenic components of a novel food, Micronesian nut Nangai (Canarium indicum), shows IgE cross-reactivity in pollen allergic patients.

BACKGROUND: New foods may present a risk for food hypersensitive patients. Several examples exist of allergic reactions caused by cross-reactive plant-derived foods, and new foods should be scrutinised before introducing them to the market. We have evaluated the clinical and serological relevance of cross-reactivity between Nangai and pollen allergens. METHODS: Cross-reactivity was examined with Maxisorp RAST (radioallergosorbent test), RAST inhibition and Western blot, using sera from patients allergic to grass, birch and mugwort pollen. None of the patients reported having seen or eaten Nangai previously. To determine the biological and clinical relevance of the cross-reactivity, histamine release (HR) test, skin prick test (SPT) and food challenge were used. RESULTS: There was prevalence for reactivity against Nangai in the group of pollen allergic patients. This cross-reactivity seems to be related--at least in part--to carbohydrate epitopes. Three out of 12 patients tested with Nangai were positive upon open challenge, but using double blind placebo controlled food challenge (DBPCFC) this could not be confirmed in two patients. The biological effects of Nangai on allergic patients were confirmed using HR and SPT. CONCLUSION: The Nangai specific IgE found among pollen allergic patients addresses the need for control of new or changed foods before introduction to the market.

Immunochemical and biological quantification of peanut extract.

Biological standardization of allergen extracts is one of the steps in the characterization of an extract. The gold standard for determination of biological potency is the skin prick test, but histamine release (HR) has been used as a convenient ex vivo method for analyzing a large number of samples. We describe the use of rabbit basophils as a tool in biological standardization. Using peanut as a model allergen, it is described how rabbits immunized for production of antiserum may become sensitized and their basophils used for histamine release experiments. It is also possible to use rabbit antiserum to passively sensitize basophils derived from naive rabbits, but the sensitivity of this method is so far 100-1000 times lower than the direct histamine release. The rabbit histamine release results are compared to an ELISA developed by means of the same antisera and by passive sensitization of human basophils using serum from a strongly sensitized peanut-allergic patient. The overall sensitivity of the methods were ELISA > HR-human cells > HR-sensitized rabbit cells > HR-passively sensitized rabbit cells. The use of rabbit basophils for biological standardizations will allow for the use of rabbit antisera.

CCR3 expression induced by IL-2 and IL-4 functioning as a death receptor for B cells.

We report that CCR3 is not expressed on freshly isolated peripheral and germinal B cells, but is up-regulated after stimulation with IL-2 and IL-4 (approximately 98% CCR3(+)). Ligation of CCR3 by eotaxin/chemokine ligand (CCL) 11 induces apoptosis in IL-2- and IL-4-stimulated primary CD19(+) (approximately 40% apoptotic cells) B cell cultures as well as B cell lines, but has no effect on chemotaxis or cell adhesion. Freshly isolated B cells express low levels of CD95 and CD95 ligand (CD95L) (19 and 21%, respectively). Expression is up-regulated on culture in the presence of a combination of IL-2, IL-4, and eotaxin/CCL11 (88% CD95 and 84% CD95L). We therefore propose that ligation of such newly induced CCR3 on peripheral and germinal B cells by eotaxin/CCL11 leads to the enhanced levels of CD95 and CD95L expression. Ligation of CD95 by its CD95L expressed on neigboring B cells triggers relevant death signaling pathways, which include an increase in levels of Bcl-2 expression, its functional activity, and the release of cytochrome c from the mitochondria into the cytosol. These events initiate a cascade of enzymatic processes of the caspase family, culminating in programmed cell death. Interaction between CCR3 and eotaxin/CCL11 may, besides promoting allergic reactions, drive activated B cells to apoptosis, thereby reducing levels of Ig production, including IgE, and consequently limit the development of the humoral immune response. The apoptotic action of eotaxin/CCL11 suggests a therapeutic modality in the treatment of B cell lymphoma.