Background: Soy lecithin is widely used as an emulsifier in processed foods, pharmaceuticals and cosmetics. Soy lecithin is composed principally of phospholipids; however, it has also been shown to contain IgE-binding proteins, albeit at a low level. A few clinical cases involving allergic reactions to soy lecithin have been reported. The purpose of this investigation is to better characterize the IgE-binding proteins typically found in lecithin. Methods: Soy lecithin proteins were isolated following solvent extraction of lipid components and then separated on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The separated lecithin proteins were immunoblotted with sera from soy-sensitive individuals to determine the pattern of IgE-binding proteins. The identity of IgE-reactive bands was determined from their N-terminal sequence. Results: The level of protein in six lecithin samples obtained from commercial suppliers ranged from 100 to 1,400 ppm. Lecithin samples showed similar protein patterns when examined by SDS-PAGE. Immunoblotting with sera from soy-sensitive individuals showed IgE binding to bands corresponding to 7, 12, 20, 39 and 57 kD. N-terminal analysis of these IgE-binding bands resulted in sequences for 3 components. The 12-kD band was identified as a methionine-rich protein (MRP) and a member of the 2S albumin class of soy proteins. The 20-kD band was found to be soybean Kunitz trypsin inhibitor. The 39-kD band was matched to a soy protein with unknown function. Conclusions: Soy lecithin contains a number of IgE-binding proteins; thus, it might represent a source of hidden allergens. These allergens are a more significant concern for soy-allergic individuals consuming lecithin products as a health supplement. In addition, the MRP and the 39-kD protein identified in this study represent newly identified IgE-binding proteins.

Keywords:
Lecithin, IgE-binding proteins, 2S soybean albumin, Food allergens
1.
Wilson TA, Meservey CM, Nicolosi RJ: Soy lecithin reduces plasma lipoprotein cholesterol and early atherogenesis in hypercholesterolemic monkeys and hamsters: Beyond linoleate. Atherosclerosis 1998;140:147–153.
2.
Porras O, Carlsson B, Fallstrom SP, Hanson LA: Detection of soy protein in lecithin, margarine and, occasionally, soy oil. Int Arch Allergy Appl Immunol 1985;78:30–32.
3.
Flider FJ: The manufacture of soybean lecithins; in Szuhaj BF, List GR (eds): Lecithins. Champaign, American Oil Chemists’ Society, 1985, pp 21–37.
4.
Awazuhara H, Kawai H, Baba M, Matsui T, Komiyama A: Antigenicity of the proteins in soy lecithin and soy oil in soybean allergy. Clin Exp Allergy 1998;28:1559–1564.
5.
Muller U, Weber W, Hoffman A, Franke S, Lange R, Vieths S: Commercial soybean lecithins: A source of hidden allergens? Z Lebensm Unters Forsch A 1998;207:341–351.
6.
Sampson HA, Burks AW: Mechanisms of food allergy. Ann Rev Nutr 1996;16:161–177.
7.
Bush RK, Hefle SL: Food allergens. Crit Rev Food Sci Nutr 1996;36(suppl):S119–S163.
8.
Bush RK, Schroeckenstein D, Meier-Davis S, Balems J, Remple D: Soybean flour asthma: Detection of allergens by immunoblotting. J Clin Immunol 1988;82:251–255.
9.
Perdu LF, Prevost A, Vallerand H, Cossart C, Passemard F: Baker’s asthma related to soybean lecithin exposure. Allergy 1994;49:159–162.
10.
Renaud C, Cardiet C, Dupond C: Allergy to soy lecithin in a child. J Pediatr Gastroenterol Nutr 1996;22:328–329.
11.
Fine SR: Possible reactions to soya lecithin in aerosols. J Allergy Clin Immunol 1991;87:600.
12.
Palm M, Monertet-Vautrin DA, Kanny G, Denery-Papini S, Fremont S: Food allergy to egg and soy lecithins. Allergy 1999;54:1116–1117.
13.
Lory OH, Rosebrough NJ, Farr AL, Randall RJ: Protein measurement with the Folin phenol reagent. J Biol Chem 1951;193:265–275.
14.
Loroz LA, Yang WH: Kunitz soybean trypsin inhibitor. A specific allergen in food anaphylaxis. N Engl J Med 1980;302:1126–1128.
15.
Burks AW, Cockrell G, Connaughton C, Guin J, West A, Helm R: Identification of peanut agglutinin and soybean trypsin inhibitor as minor legume allergens. Int Arch Allergy Immunol 1994;105:143–149.
16.
Revilleza MJ, Galvez AF, Krenz DC, De Lumen BO: An 8 kDa methionine-rich protein (MRP) from soybean (Glycine max) cotyledon: Identification, purification and N-terminal sequence. J Agric Food Chem 1996;44:2930–2935.
17.
Odani S, Koide T, Ono T: Amino acid sequence of a soybean (Glycine max) seed polypeptide having a poly(L-aspartic acid) structure. J Biol Chem 1987;262:10502–10505.
18.
Rico M, Bruix M, Gonzalez C, Monsalve R, Rodriguez R: 1H NMR assignment and global fold of napin Bnlb, a representative 2S albumin seed protein. Biochemistry 1996;35:15672–15682.
19.
Gayler KR, Kolivas S, McFarlane AJ, Lilley GG, Baldi M, Blagrove RJ, Johnson ED: Biosynthesis, cDNA and amino acid sequences of a precursor of conglutin delta, a sulfur-rich protein from Lupinus angustifolius. Plant Mol Biol 1999;15:879–893.
20.
Kleber-Janke T, Crameri R, Appenzeller U, Schlaak M, Becker W-M: Selective cloning of peanut allergens, including profilin and 2S albumins by phage display technology. Int Arch Allergy Immunol 1999;119:265–274.
21.
Ogawa T, Bando N, Tsuji H, Okajima H, Nishikawa K, Sasaoka K: Investigation of the IgE-binding proteins in soybeans by immunoblotting with the sera of the soybean-sensitive patients with atopic dermatitis. J Nutr Sci Vitaminol (Tokyo) 1991;37:555–565.
22.
Herian A, Taylor S, Bush RK: Identification of soybean allergens by immunoblotting with sera from soy-allergic adults. Int Arch Allergy Appl Immunol 1990;92:193–198.
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2001
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