Isolation and characterization of proteic allergens in refined peanut oil

Abstract

Allergic reactions to peanut oil are very much debated, even if the responsibility of peanut oil has been evoked in several cases of adverse reactions, including death related to severe asthma. The aim of the present study was to investigate the presence of allergenic proteins in peanut oil. Proteins were extracted from commercial refined peanut oil, with a relative content in the order of 0.1-0.2 microg per g of oil, and molecular sizes ranging from 14 up to 76kDa in SDS-PAGE. Eight protein bands were systematically observed in crude, neutralized and refined oils, with a molecular mass ranging from approximately 14 to 76 kDa, including one at 18 kDa which was identified by Western blot performed with serum from two allergic patients. The protein extract gave positive IgE-RIA with patient sera, positive in vitro leucocyte histamine release tests and positive skin-prick tests in allergic patients. The allergenic protein was purified by HPLC and [125I] iodide-labelled. It had an isoelectric point at 4.5 in isoelectrofocusing. In conclusion, we have demonstrated the presence of allergenic proteins in crude and refined peanut oil. These proteins are the same size as two allergens previously described in peanut protein extracts.

Scientific Opinion on the evaluation of allergenic foods and food ingredients for labelling purposes

“…However, refined peanut oil may contain sufficient peanut allergenic proteins to elicit a reaction in highly sensitive individuals (Olszewski et al, 1998). One of these proteins was recognised by IgE antibodies from a population of 11 peanut-allergic patients, four of whom reacted to commercially available refined peanut oils from the European market during a DBPCFC.…”

Opinion of the Scientific Panel on Dietetic products, nutrition and allergies [NDA] related to a notification from FEDIOL and IMACE on fully refined peanut oil and fat pursuant to Article 6 paragraph 11 of Directive 2000/13/EC

“…However, they did not detect any protein in two other "cold pressed peanut oil" or in any of the three "hot-pressed peanut oils" tested. Olszewski et al (1998) using bicinchoninic protein acid assay revealed 3.4 µg/g of protein in "crude peanut oil" and 0.2 µg/g of protein in "neutralized peanut oil". They also tested six commercially available "refined peanut oil" and reported the protein content to be between 0.1-0.2 µg/g of oil.…”

“…A total of 6 studies have addressed the immunochemical characterisation of the protein component of peanut oils (Nordlee et al, 1981;Hoffman et al, 1994;Teuber et al, 1997;Olszewski et al, 1998;Kull et al, 1999;Peeters et al, 2004 The applicant also states that there is no consensus on the most appropriate analytical methods for measurement of protein content of edible oils.…”

“…The two methods described by the applicant, based on the available evidence in this area, are the "Total Protein Methods" and the "Immunochemical Methods". A total of 8 studies (Hoffman et al, 1994;Yeung and Collins 1996;Teuber et al, 1997;Olszewski et al, 1998;Skinner and Haynes, 1998;Crevel et al, 2000a;Crevel et al, 2000b;Peeters et al, 2004) have addressed the protein content of "peanut oils".…”

Naseptin® Nasal Cream ’contains peanut oil’

“…2 It also mentioned an earlier study that demonstrated the persistence of small amounts of allergenic protein in peanut oil despite re nement. 3 Although the Committee on Safety of Medicines has determined that there is insuf cient evidence to conclude that exposure to topical medicines containletters to the editorsing peanut oil leads to sensitization to peanut protein, it has issued a precautionary recommendation that patients with known peanut allergy should avoid such medicines. Indeed, the labelling of these products is to be updated with new warnings.…”