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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: Differences between heat-treated raw and commercial peanut extracts by skin testing and immunoblotting

Authors
item Maleki, Soheila
item Casillas, Adrian -
item Kaza, Ujwala -
item Wilson, Brian -
item Nesbit, Jacqueline
item Reimoneqnue, Chantrel -
item Cheng, Hsiaopo
item Bahna, Sami -

Submitted to: Annals of Allergy, Asthma and Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 25, 2010
Publication Date: December 10, 2010
Citation: Maleki, S.J., Casillas, A.M., Kaza, U., Wilson, B., Nesbit, J.B., Reimoneqnue, C., Cheng, H., Bahna, S.L. 2010. Differences between heat-treated raw and commercial peanut extracts by skin testing and immunoblotting. Annals of Allergy, Asthma and Immunology. 105:451-457.

Interpretive Summary: Peanut is generally consumed in a heat-treated form, yet the commonly available extracts for diagnostic purposes are derived from raw peanuts. Raw and heat-treated samples were prepared and compared with commercially available peanut extracts regarding skin test (ST) reactivity and serum IgE reactivity. Protein profiles of three commercial and 3 laboratory-prepared extracts (raw, roasted, and boiled) were compared and used for ST in 24 patients that were presented to the clinic with suspected allergy to peanut or another food. Twelve of the 24 patients had peanut allergy. Of the 12 peanut allergic patients subject to ST, 2 did not react to any of the extracts, and only 2 reacted to all six extracts. Majority of the patients had either an equal or higher ST reactivity to the heat-treated extracts. IgE binding to Ara h 2 was demonstrated in nearly all patients, regardless of their clinical reactivity. The use of differentially prepared and/or processed peanut extracts can lead to significant discrepancies between the results obtained from ST and IgE specificity. Using a mixture of differently processed extracts may enhance the diagnostic reliability of these tests.

Technical Abstract: Peanut is generally consumed in a heat-treated form, yet the commonly available extracts for diagnostic purposes are derived from raw peanuts. Raw and heat-treated samples were prepared and compared with commercially available peanut extracts regarding SPT reactivity and serum IgE reactivity. Protein profiles of three commercial and 3 laboratory-prepared extracts (raw, roasted, and boiled) were compared using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, western blot, and used for SPT in 24 patients that were presented to the clinic with suspected allergy to peanut or another food. Twelve of the 24 patients had a positive peanut challenge or a strong history of peanut allergy. Serum was obtained from all patients to measure total IgE and specific IgE. Boiled extract had the highest SPT specificity (75% vs 45 to 64% for the other extracts). Of the 12 peanut allergic patients, two did not react to any of the extracts, and only two reacted to all six extracts. Majority of the patients had either an equal or higher SPT reactivity to the heat-treated extracts. Specific IgE levels did not correlate with either SPT or clinical reactivity. IgE binding to Ara h 2 was demonstrated in nearly all patients, regardless of their clinical reactivity. The use of differentially prepared and/or processed peanut extracts can lead to significant discrepancies between the results obtained from SPT and IgE specificity. Using a mixture of differently processed extracts may enhance the diagnostic reliability of these tests.

Last Modified: 12/27/2014
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