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United States Department of Agriculture

Agricultural Research Service

Research Project: Primary and Secondary Prevention of Peanut and Tree Nut Allergy

Location: Food Processing and Sensory Quality Research

Title: IgE binding to peanut allergens is inhibited by combined D-aspartic and D-glutamic acids

Authors
item Chung, Si-Yin
item Reed, Shawndrika

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 3, 2014
Publication Date: July 1, 2014
Citation: Chung, S., Reed, S.S. 2014. IgE binding to peanut allergens is inhibited by combined D-aspartic and D-glutamic acids. Food Chemistry. 166:248-253.

Interpretive Summary: D-amino acids (D-aas) are enantiomers, or mirror images of L-amino acids (L-aas). They occur in living organisms and humans, and can form from L-aas in foods during heat processing. Some D-aas have been used to bind and remove immunoglobulin E (IgE) antibodies from plasma of people with allergy and asthma. Our objectives were to determine if D-aas bind or inhibit IgE binding to peanut allergens, and if they are more effective than L-aas in this respect. Several D-aa cocktails were prepared: D-aspartic acid (D-Asp), D-glutamic acid (D-Glu), D-[Asp/Glu], hydrophilic D-aas, and hydrophobic D-aas. L-aa cocktails and a control with no amino acids were also made. Each sample was mixed with diluted pooled plasma from donors with peanut allergy, and tested for IgE binding in immunoassays such as, ELISA and Western blots. Results showed that among the D-aa cocktails, only D-[Asp/Glu] (4 mg/mL) inhibited 75% IgE binding to peanut allergens. D-Asp or D-Glu alone did not inhibit IgE binding. A higher inhibition was seen with D-[Asp/Glu] than with the L-form. We concluded that IgE may have an affinity for D-[Asp/Glu], and that D-[Asp/Glu] have a higher affinity for IgE than the L-forms. The significance of this study is that our method may benefit people with peanut allergy by removing IgE from their plasma extracorporeally (i.e., outside the body), and thus reducing their allergic reactions to peanuts.

Technical Abstract: D-amino acids (D-aas) are reported to bind to IgE antibodies from people with allergy and asthma. The objectives of this study were to determine if D-aas bind or inhibit IgE binding to peanut allergens, and if they are more effective than L-amino acids (L-aas) in this respect. Several D-aa cocktails at various concentrations were prepared: D-Asp, D-Glu, D-[Asp/Glu], hydrophilic D-aa, and hydrophobic D-aa. L-aas was prepared in the same way along with a buffer control containing no amino acids. Each sample was mixed (1:1) (v:v) with diluted pooled plasma (IgE antibodies) from donors with peanut allergy, and subjected to inhibition ELISA and Western blot assays for IgE binding. Results showed that among the amino acid cocktails tested, only D-[Asp/Glu] (4 mg/mL) inhibited 75% IgE binding to peanut allergens. D-Asp or D-Glu alone did not inhibit IgE binding. A higher inhibition was seen with D-[Asp/Glu] than with the L-form. We concluded that IgE had an affinity for D-[Asp/Glu] but not for D-Asp or D-Glu alone, and that D-[Asp/Glu] was more effective than the L-form in the binding of IgE. The research implies that D-[Asp/Glu] may have the potential for use in extracorporeal treatment to remove IgE from plasma of individuals with peanut allergy.

Last Modified: 11/27/2014
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