As peanut allergy is an increasing public health risk, affecting over 1% of the United States and United Kingdom school children, it is important that methods and reagents for accurate diagnosis of food allergy and detection of allergenic foods are reliable and consistent. Given that most current experimental, diagnostic, and detection tests rely on the presence of soluble allergens in food extracts, we investigated the effects of thermal processing on the solubility and IgE binding of the major peanut allergens, Ara h 1 and Ara h 2. The soluble and insoluble fractions of peanuts that were boiled, fried, and roasted were subjected to electrophoresis and Western blot analysis using anti-Ara h 1 and anti-Ara h 2 antibodies and serum IgE from peanut allergic individuals. Overall protein solubility is reduced with processing and IgE binding increases in the insoluble fractions, due mostly to the increase in the amount of insoluble proteins, with increased time of heating in all processes tested. Therefore, it can be concluded that thermal processing of peanuts alters solubility, and the differences in protein solubility within various extract preparations may contribute to inconsistent skin prick test and immunoassay results, particularly when nonstandardized reagents are used.

Background Recent immunological data demonstrated that dendritic cells preferentially recognize advanced glycation end product (AGE) modified proteins, upregulate expression of the receptor for AGE (RAGE), and consequently bias the immune response towards allergy. Methods Peanut extract was characterized by mass spectrometry (MS) to elucidate the specific residues and specific AGE modifications found in raw and roasted peanuts and on rAra h 1 that was artificially glycated by incubation with glucose or xylose. The binding of the RAGE-V1C1 domain to peanut allergens was assessed by PAGE and Western analysis with anti-Ara h 1, 2, and 3 antibodies. IgE binding to rAra h 1 was also assessed using the same methods. Results AGE modifications were found on Ara h 1 and Ara h 3 in both raw and roasted peanut extract. No AGE modifications were found on Ara h 2. MS and Western blot analysis demonstrated RAGE binds selectively to Ara h 1 and Ara h 3 derived from peanut extract whereas the analysis failed to demonstrate Ara h 2 binding to RAGE. rAra h 1 with no AGE modifications did not bind RAGE, however after AGE modification with xylose, rAra h 1 bound to RAGE. Conclusions AGE modifications to Ara h 1 and Ara h 3 can be found in both raw and roasted peanuts. RAGE was demonstrated to selectively interact with AGE modified rAra h 1. If sensitization to peanut allergens occurs in dendritic cells via RAGE interactions, these cells are likely interacting with modified Ara h 1, and Ara h 3, and not Ara h 2.

The MLL gene at chromosome band 11q23 is commonly involved in reciprocal translocations detected in acute leukemias. A number of experiments show that the resulting MLL fusion genes directly contribute to leukemogenesis. Among the many known MLL fusion partners, AF4 is relatively common, particularly in acute lymphoblastic leukemia in infants. The AF4 protein interacts with the product of another gene, AF9, which is also fused to MLL in acute leukemias. Based on mapping studies of the AF9-binding domain of AF4, we have developed a peptide, designated PFWT, which disrupts the AF4-AF9 interaction in vitro and in vivo. We provide evidence that this peptide is able to inhibit the proliferation of leukemia cells with t(4;11) chromosomal translocations expressing MLL-AF4 fusion genes. Further, we show that this inhibition is mediated through apoptosis. Importantly, the peptide does not affect the proliferative capacity of hematopoietic progenitor cells. Our findings indicate that the AF4-AF9 protein complex is a promising new target for leukemia therapy and that the PFWT peptide may serve as a lead compound for drug development.

The thermal stability and IgE binding of raw and boiled shrimp extracts and the tropomyosins (TM) have not been reported. In this study, we compare the stability of raw and boiled shrimp TM of Litopenaeus vannamei and evaluate how boiling may alter the allergenicity of L. vannamei. Extracts were prepared from raw and boiled shrimp and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis. The IgE-binding of the extracts was determined by western-blot and competitive inhibition enzyme-linked immunosorbent assay (iELISA). The TM was then purified from raw and boiled shrimp, the secondary structures analyzed by circular dichroism (CD) spectroscopy, and the IgE binding compared by slot blot analysis. The soluble protein content decreased and the higher molecular weight proteins increased in the extracts from boiled versus raw shrimp. Similar IgE binding characteristics were seen by extracts when using western blot analysis. Although iELISA results showed that extracts from raw shrimp bound higher IgE than extracts from boiled shrimp, dot-blot assay demonstrates higher IgE binding to purified TM from boiled shrimp than raw shrimp. The purified TM had a typical alpha-helical secondary structure and the stability of boiled TM was lower than that of raw TM. Extracts from boiled shrimp produce lower IgE binding than extracts from raw shrimp, which suggest that boiling can be used as a tool in attempting to reduce shrimp allergenicity. However, the purified TM from boiled shrimp, which shows enhanced IgE binding over that of raw shrimp, may be a more effective antigen in diagnosing shrimp allergy through immunoassay.

Enhanced IgE binding to roasted Ara h 1 could be due to alterations such as chemical modifications to individual amino acids or increased epitope exposure. IgE binding is significantly reduced with loss of structure.

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Vicilin-buried peptides (VBPs) from edible plants are derived from the N-terminal leader sequences (LSs) of seed storage proteins. VBPs are defined by a common α-hairpin fold mediated by conserved CxxxCx(10–14)CxxxC motifs. Here, peanut and walnut VBPs were characterized as potential mediators of both peanut/walnut allergenicity and cross-reactivity despite their low (∼17%) sequence identity. The structures of one peanut (AH1.1) and 3 walnut (JR2.1, JR2.2, JR2.3) VBPs were solved using solution NMR, revealing similar α-hairpin structures stabilized by disulfide bonds with high levels of surface similarity. Peptide microarrays identified several peptide sequences primarily on AH1.1 and JR2.1, which were recognized by peanut-, walnut-, and dual-allergic patient IgE, establishing these peanut and walnut VBPs as potential mediators of allergenicity and cross-reactivity. JR2.2 and JR2.3 displayed extreme resilience against endosomal digestion, potentially hindering epitope generation and likely contributing to their reduced allergic potential.