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Diagnosing IgE-mediated hypersensitivity to sesame by an immediate-reading “contact test” with sesame oil

2011; Elsevier BV; Volume: 127; Issue: 6 Linguagem: Inglês

10.1016/j.jaci.2011.01.050

1097-6825

Cristiana Alonzi, Paolo Campi, Francesco Gaeta, Fernando Pineda, Antonino Romano,

Allergic Rhinitis and Sensitization

To the Editor:Sesame allergy has been reported as increasingly frequent in both adults and children,1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar in particular in Europe (2% to 4% of total food allergies).2Gangur V. Kelly C. Navuluri L. Sesame allergy: a growing food allergy of global proportions?.Ann Allergy Asthma Immunol. 2005; 95: 4-11Abstract Full Text PDF PubMed Google Scholar This phenomenon may be a result of the increased use of sesame in vegetarian dietary regimens and of the introduction of exotic foods.Most literature data concerning sesame allergy are reports of single cases or case series. In a series of 9 patients with hypersensitivity reactions to sesame seeds, Kanny et al3Kanny G. De Hauteclocque C. Moneret-Vautrin D.A. Sesame seed and sesame seed oil contain masked allergens of growing importance.Allergy. 1996; 51: 952-957PubMed Google Scholar described 2 patients who also had anaphylactic reactions to sesame oil. In these patients, an IgE-mediated hypersensitivity was diagnosed on the basis of positive responses to both skin prick tests (SPTs) with sesame seed flour and double-blind placebo-controlled food challenges. Two other cases of immediate hypersensitivity to sesame seeds and sesame-containing cosmetic oils have been described by Pecquet et al4Pecquet C. Leynadier F. Saïag P. Immediate hypersensitivity to sesame in foods and cosmetics.Contact Dermatitis. 1998; 39: 313Crossref PubMed Scopus (32) Google Scholar: these subjects displayed negative results to SPTs with a commercial sesame extract but positive ones with crushed sesame seeds. In both studies,3Kanny G. De Hauteclocque C. Moneret-Vautrin D.A. Sesame seed and sesame seed oil contain masked allergens of growing importance.Allergy. 1996; 51: 952-957PubMed Google Scholar, 4Pecquet C. Leynadier F. Saïag P. Immediate hypersensitivity to sesame in foods and cosmetics.Contact Dermatitis. 1998; 39: 313Crossref PubMed Scopus (32) Google Scholar specific IgE assays were negative. However, 2 studies5Zavalkoff S. Kagan R. Joseph L. St-Pierre Y. Clarke A. The value of sesame-specific IgE levels in predicting sesame allergy.J Allergy Clin Immunol. 2008; 121: 1508-1510Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar, 6Maloney J.M. Rudengren M. Ahlstedt S. Bock S.A. Sampson H.A. The use of serum-specific IgE measurements for the diagnosis of peanut, tree nut, and seed allergy.J Allergy Clin Immunol. 2008; 122: 145-151Abstract Full Text Full Text PDF PubMed Scopus (208) Google Scholar demonstrated that a titer of sesame-specific IgE lower than 0.35 kUA/L is useful to rule out an IgE-mediated hypersensitivity to sesame. Nevertheless, according to Zavalkoff et al,5Zavalkoff S. Kagan R. Joseph L. St-Pierre Y. Clarke A. The value of sesame-specific IgE levels in predicting sesame allergy.J Allergy Clin Immunol. 2008; 121: 1508-1510Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar oral provocation tests should be offered to all patients to confirm the diagnosis of sesame allergy irrespective of SPT or sesame-specific IgE results, even though in patients with a sesame-specific IgE level <0.35 kUA/L, the risk of an allergic reaction is extremely low. In this connection, cases of anaphylaxis have been reported in patients presenting negative results in both SPTs and specific IgE assays.7Stern A. Wüthrich B. Non-IgE-mediated anaphylaxis to sesame.Allergy. 1998; 53: 325-326Crossref PubMed Scopus (29) Google ScholarIn a study by Leduc et al,1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar which included SDS-PAGE immunoblotting of a purified oil body fraction, Ses i 4 and Ses i 5 (2 oleosins from sesame seeds) were recognized by the IgE from 29 of the 32 patients with hypersensitivity reactions to sesame. Six of them reported reactions to sesame oil and presented negative responses to both SPTs and specific IgE assays with sesame seeds. Thus, these authors1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar highlighted the need to improve the quality of sesame extract for diagnosis.We report 3 cases of immediate reactions to sesame. Patient 1 was a 42-year-old man with 2 anaphylactic reactions after ingestion of breadsticks and candy, respectively; both products contained sesame. Patient 2 was a 28-year-old man with 2 urticarial and angioedematous reactions within 10 minutes after the ingestion of bread containing sesame seeds. Patient 3 was a 38-year-old man with an 8-year history of several urticarial and angioedematous reactions within 30 minutes after ingesting sesame-containing foods, such as bread, crackers, and products cooked in sesame oil. Case histories were not suggestive of any other food allergies or atopic manifestations. They underwent SPTs with a panel of 2 commercial extracts of food allergens including sesame (Stallergènes, Paris, France; ALK-Abelló, Madrid, Spain), with negative results.Like Leduc et al,1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar we also performed SPTs with natural sesame seed crushed in saline. Patient 1 displayed an immediate response (maximum wheal diameter of 5 mm, surrounded by erythema), whereas patients 2 and 3 had a negative response. No sesame-specific IgE were detected in any patient (<0.10 kUA/L, ImmunoCAP; Phadia, Uppsala, Sweden). SPTs with commercial sesame oil (Crudigno, Organic Oils Spa; Mugnano, Perugia, Italy) were performed on the volar side of the forearm; the drops of oil were wiped away with a paper tissue after the SPTs, which were negative. An immediate-reading "contact test" with sesame oil was performed by applying on the volar side of the forearm a square of filter paper (10 × 10 mm) dipped in sesame oil (Crudigno) and removing it after 20 minutes. On the contact side, patient 2 presented a wheal reaction the same size as the filter paper, whereas patients 1 and 3 presented several 4-mm-diameter wheals also involving the surrounding area (diameters 2 and 5 cm, respectively). Immediate-reading contact tests with 2 tolerated oils were also performed on each patient by applying on the volar side of the forearm a square of filter paper (10 × 10 mm) dipped in extra-virgin olive oil (Crudigno) and refined peanut oil (Dante Oil, Mataluni Spa; Montesarchio, Benevento, Italy), with negative results. The immediate-reading contact test with sesame oil was negative in 10 healthy subjects, 5 of whom used sesame-containing foods regularly in their diet.As regards patients 2 and 3, considering negative results of in vivo and in vitro tests as well as the fact that they had not experienced severe reactions, an open food challenge was performed to firmly establish the diagnosis. In accordance with Kanny et al,3Kanny G. De Hauteclocque C. Moneret-Vautrin D.A. Sesame seed and sesame seed oil contain masked allergens of growing importance.Allergy. 1996; 51: 952-957PubMed Google Scholar we administered increasing doses of sesame seeds (0.05, 0.5, 1, 5, and 10 g) every 30 minutes. Both patients experienced urticarial reactions: the first one 20 minutes after the dose of 0.5 g, the second 15 minutes after the dose of 1 g. Consequently, no oral provocation test with sesame oil was performed. We did not perform an oral provocation test in patient 1, because of the previous anaphylactic shock and positivity to SPTs with sesame seeds.Specific IgE was further analyzed by immunoblot experiments with an extract of sesame seeds and sesame oil (Fig 1). All patients' sera (diluted 1:4 in PBS-Tween 0.5%) showed an IgE binding to several proteins of the oil bodies (membrane lipoproteins), such as oleosins (the band with molecular mass around 15-17 kDa).To our knowledge, these are the first cases of hypersensitivity to sesame diagnosed by a simple immediate-reading contact test with sesame oil. Because oleosins are hydrophobic and can not be solubilized in normal saline, a negative prick-to-prick test with crushed sesame seeds is not sufficient to exclude sesame allergy, especially in subjects in whom specific IgE is directed prevalently to liposoluble proteins. For this reason, patients with histories of adverse reactions to sesame should also be tested with an immediate-reading "contact test" with sesame oil, in which oleosins are anchored onto the surface by its central hydrophobic domain and can easily penetrate the skin. Negative results in SPTs with sesame oil can be explained by the fact that the oil drops were wiped away immediately after testing and there was not enough time to allow oil to penetrate into the skin.The data from Leduc et al1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar and our data indicate that sensitization to oleosins can play an etiologic role in some subjects with immediate reactions to sesame products. Therefore, sensitization to oleosins might constitute a diagnostic problem in both adults and children. In effect, even though all our patients were adults, one of the patients described by Leduc et al1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar was a 9-year-old girl.Few data exist on the allergenicity of other vegetable oils. The presence of oleosins has been shown in some of them. In peanut oil, for example, the allergenicity of oleosins has been established,8Pons L. Chery C. Romano A. Namour F. Artesani M.C. Guéant J.L. The 18 kDa peanut oleosin is a candidate allergen for IgE-mediated reactions to peanuts.Allergy. 2002; 57: 88-93Crossref PubMed Google Scholar even though commercially available, refined peanut oil has been proven to be well tolerated by most subjects with peanut allergy.9Crevel R.W. Kerkhoff M.A. Koning M.M. Allergenicity of refined vegetable oils.Food Chem Toxicol. 2000; 38: 385-393Crossref PubMed Scopus (120) Google Scholar In effect, the major refined oils are not thought to induce symptoms in susceptible individuals.10Morisset M. Moneret-Vautrin D.A. Kanny G. Guénard L. Beaudouin E. Flabbée J. et al.Thresholds of clinical reactivity to milk, egg, peanut and sesame in immunoglobulin E-dependent allergies: evaluation by double-blind or single-blind placebo-controlled oral challenges.Clin Exp Allergy. 2003; 33: 1046-1051Crossref PubMed Scopus (174) Google Scholar There are commercial available crude and cold-pressed peanut oils that contain proteins. Sesame oil differs from the others because it is typically available as an unrefined, crude oil, which contains a significantly higher amount (3-13 μg/g) of proteins.9Crevel R.W. Kerkhoff M.A. Koning M.M. Allergenicity of refined vegetable oils.Food Chem Toxicol. 2000; 38: 385-393Crossref PubMed Scopus (120) Google Scholar, 10Morisset M. Moneret-Vautrin D.A. Kanny G. Guénard L. Beaudouin E. Flabbée J. et al.Thresholds of clinical reactivity to milk, egg, peanut and sesame in immunoglobulin E-dependent allergies: evaluation by double-blind or single-blind placebo-controlled oral challenges.Clin Exp Allergy. 2003; 33: 1046-1051Crossref PubMed Scopus (174) Google ScholarOur immunoblot experiments detected serum-specific IgE to the oleosins contained in sesame oil. The sera of our patients also displayed a higher IgE-reactivity to other liposoluble proteins not yet characterized (Fig 1, D). Like oleosins, such lipoproteins are hydrophobic, and because they can not be solubilized in normal saline, they are not present in commercial extracts. Our data suggest that patients with histories of immediate reactions to sesame products and positive results in immediate-reading contact tests with sesame oil should be instructed to avoid all sesame products, including oil. However, further studies in larger samples are needed to confirm the usefulness of this immediate-reading contact test and to validate such advice. To the Editor: Sesame allergy has been reported as increasingly frequent in both adults and children,1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar in particular in Europe (2% to 4% of total food allergies).2Gangur V. Kelly C. Navuluri L. Sesame allergy: a growing food allergy of global proportions?.Ann Allergy Asthma Immunol. 2005; 95: 4-11Abstract Full Text PDF PubMed Google Scholar This phenomenon may be a result of the increased use of sesame in vegetarian dietary regimens and of the introduction of exotic foods. Most literature data concerning sesame allergy are reports of single cases or case series. In a series of 9 patients with hypersensitivity reactions to sesame seeds, Kanny et al3Kanny G. De Hauteclocque C. Moneret-Vautrin D.A. Sesame seed and sesame seed oil contain masked allergens of growing importance.Allergy. 1996; 51: 952-957PubMed Google Scholar described 2 patients who also had anaphylactic reactions to sesame oil. In these patients, an IgE-mediated hypersensitivity was diagnosed on the basis of positive responses to both skin prick tests (SPTs) with sesame seed flour and double-blind placebo-controlled food challenges. Two other cases of immediate hypersensitivity to sesame seeds and sesame-containing cosmetic oils have been described by Pecquet et al4Pecquet C. Leynadier F. Saïag P. Immediate hypersensitivity to sesame in foods and cosmetics.Contact Dermatitis. 1998; 39: 313Crossref PubMed Scopus (32) Google Scholar: these subjects displayed negative results to SPTs with a commercial sesame extract but positive ones with crushed sesame seeds. In both studies,3Kanny G. De Hauteclocque C. Moneret-Vautrin D.A. Sesame seed and sesame seed oil contain masked allergens of growing importance.Allergy. 1996; 51: 952-957PubMed Google Scholar, 4Pecquet C. Leynadier F. Saïag P. Immediate hypersensitivity to sesame in foods and cosmetics.Contact Dermatitis. 1998; 39: 313Crossref PubMed Scopus (32) Google Scholar specific IgE assays were negative. However, 2 studies5Zavalkoff S. Kagan R. Joseph L. St-Pierre Y. Clarke A. The value of sesame-specific IgE levels in predicting sesame allergy.J Allergy Clin Immunol. 2008; 121: 1508-1510Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar, 6Maloney J.M. Rudengren M. Ahlstedt S. Bock S.A. Sampson H.A. The use of serum-specific IgE measurements for the diagnosis of peanut, tree nut, and seed allergy.J Allergy Clin Immunol. 2008; 122: 145-151Abstract Full Text Full Text PDF PubMed Scopus (208) Google Scholar demonstrated that a titer of sesame-specific IgE lower than 0.35 kUA/L is useful to rule out an IgE-mediated hypersensitivity to sesame. Nevertheless, according to Zavalkoff et al,5Zavalkoff S. Kagan R. Joseph L. St-Pierre Y. Clarke A. The value of sesame-specific IgE levels in predicting sesame allergy.J Allergy Clin Immunol. 2008; 121: 1508-1510Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar oral provocation tests should be offered to all patients to confirm the diagnosis of sesame allergy irrespective of SPT or sesame-specific IgE results, even though in patients with a sesame-specific IgE level <0.35 kUA/L, the risk of an allergic reaction is extremely low. In this connection, cases of anaphylaxis have been reported in patients presenting negative results in both SPTs and specific IgE assays.7Stern A. Wüthrich B. Non-IgE-mediated anaphylaxis to sesame.Allergy. 1998; 53: 325-326Crossref PubMed Scopus (29) Google Scholar In a study by Leduc et al,1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar which included SDS-PAGE immunoblotting of a purified oil body fraction, Ses i 4 and Ses i 5 (2 oleosins from sesame seeds) were recognized by the IgE from 29 of the 32 patients with hypersensitivity reactions to sesame. Six of them reported reactions to sesame oil and presented negative responses to both SPTs and specific IgE assays with sesame seeds. Thus, these authors1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar highlighted the need to improve the quality of sesame extract for diagnosis. We report 3 cases of immediate reactions to sesame. Patient 1 was a 42-year-old man with 2 anaphylactic reactions after ingestion of breadsticks and candy, respectively; both products contained sesame. Patient 2 was a 28-year-old man with 2 urticarial and angioedematous reactions within 10 minutes after the ingestion of bread containing sesame seeds. Patient 3 was a 38-year-old man with an 8-year history of several urticarial and angioedematous reactions within 30 minutes after ingesting sesame-containing foods, such as bread, crackers, and products cooked in sesame oil. Case histories were not suggestive of any other food allergies or atopic manifestations. They underwent SPTs with a panel of 2 commercial extracts of food allergens including sesame (Stallergènes, Paris, France; ALK-Abelló, Madrid, Spain), with negative results. Like Leduc et al,1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar we also performed SPTs with natural sesame seed crushed in saline. Patient 1 displayed an immediate response (maximum wheal diameter of 5 mm, surrounded by erythema), whereas patients 2 and 3 had a negative response. No sesame-specific IgE were detected in any patient (<0.10 kUA/L, ImmunoCAP; Phadia, Uppsala, Sweden). SPTs with commercial sesame oil (Crudigno, Organic Oils Spa; Mugnano, Perugia, Italy) were performed on the volar side of the forearm; the drops of oil were wiped away with a paper tissue after the SPTs, which were negative. An immediate-reading "contact test" with sesame oil was performed by applying on the volar side of the forearm a square of filter paper (10 × 10 mm) dipped in sesame oil (Crudigno) and removing it after 20 minutes. On the contact side, patient 2 presented a wheal reaction the same size as the filter paper, whereas patients 1 and 3 presented several 4-mm-diameter wheals also involving the surrounding area (diameters 2 and 5 cm, respectively). Immediate-reading contact tests with 2 tolerated oils were also performed on each patient by applying on the volar side of the forearm a square of filter paper (10 × 10 mm) dipped in extra-virgin olive oil (Crudigno) and refined peanut oil (Dante Oil, Mataluni Spa; Montesarchio, Benevento, Italy), with negative results. The immediate-reading contact test with sesame oil was negative in 10 healthy subjects, 5 of whom used sesame-containing foods regularly in their diet. As regards patients 2 and 3, considering negative results of in vivo and in vitro tests as well as the fact that they had not experienced severe reactions, an open food challenge was performed to firmly establish the diagnosis. In accordance with Kanny et al,3Kanny G. De Hauteclocque C. Moneret-Vautrin D.A. Sesame seed and sesame seed oil contain masked allergens of growing importance.Allergy. 1996; 51: 952-957PubMed Google Scholar we administered increasing doses of sesame seeds (0.05, 0.5, 1, 5, and 10 g) every 30 minutes. Both patients experienced urticarial reactions: the first one 20 minutes after the dose of 0.5 g, the second 15 minutes after the dose of 1 g. Consequently, no oral provocation test with sesame oil was performed. We did not perform an oral provocation test in patient 1, because of the previous anaphylactic shock and positivity to SPTs with sesame seeds. Specific IgE was further analyzed by immunoblot experiments with an extract of sesame seeds and sesame oil (Fig 1). All patients' sera (diluted 1:4 in PBS-Tween 0.5%) showed an IgE binding to several proteins of the oil bodies (membrane lipoproteins), such as oleosins (the band with molecular mass around 15-17 kDa). To our knowledge, these are the first cases of hypersensitivity to sesame diagnosed by a simple immediate-reading contact test with sesame oil. Because oleosins are hydrophobic and can not be solubilized in normal saline, a negative prick-to-prick test with crushed sesame seeds is not sufficient to exclude sesame allergy, especially in subjects in whom specific IgE is directed prevalently to liposoluble proteins. For this reason, patients with histories of adverse reactions to sesame should also be tested with an immediate-reading "contact test" with sesame oil, in which oleosins are anchored onto the surface by its central hydrophobic domain and can easily penetrate the skin. Negative results in SPTs with sesame oil can be explained by the fact that the oil drops were wiped away immediately after testing and there was not enough time to allow oil to penetrate into the skin. The data from Leduc et al1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar and our data indicate that sensitization to oleosins can play an etiologic role in some subjects with immediate reactions to sesame products. Therefore, sensitization to oleosins might constitute a diagnostic problem in both adults and children. In effect, even though all our patients were adults, one of the patients described by Leduc et al1Leduc V. Moneret-Vautrin D.A. Tzen J.T. Morisset M. Guerin L. Kanny G. Identification of oleosins as major allergens in sesame seed allergic patients.Allergy. 2006; 61: 349-356Crossref PubMed Scopus (140) Google Scholar was a 9-year-old girl. Few data exist on the allergenicity of other vegetable oils. The presence of oleosins has been shown in some of them. In peanut oil, for example, the allergenicity of oleosins has been established,8Pons L. Chery C. Romano A. Namour F. Artesani M.C. Guéant J.L. The 18 kDa peanut oleosin is a candidate allergen for IgE-mediated reactions to peanuts.Allergy. 2002; 57: 88-93Crossref PubMed Google Scholar even though commercially available, refined peanut oil has been proven to be well tolerated by most subjects with peanut allergy.9Crevel R.W. Kerkhoff M.A. Koning M.M. Allergenicity of refined vegetable oils.Food Chem Toxicol. 2000; 38: 385-393Crossref PubMed Scopus (120) Google Scholar In effect, the major refined oils are not thought to induce symptoms in susceptible individuals.10Morisset M. Moneret-Vautrin D.A. Kanny G. Guénard L. Beaudouin E. Flabbée J. et al.Thresholds of clinical reactivity to milk, egg, peanut and sesame in immunoglobulin E-dependent allergies: evaluation by double-blind or single-blind placebo-controlled oral challenges.Clin Exp Allergy. 2003; 33: 1046-1051Crossref PubMed Scopus (174) Google Scholar There are commercial available crude and cold-pressed peanut oils that contain proteins. Sesame oil differs from the others because it is typically available as an unrefined, crude oil, which contains a significantly higher amount (3-13 μg/g) of proteins.9Crevel R.W. Kerkhoff M.A. Koning M.M. Allergenicity of refined vegetable oils.Food Chem Toxicol. 2000; 38: 385-393Crossref PubMed Scopus (120) Google Scholar, 10Morisset M. Moneret-Vautrin D.A. Kanny G. Guénard L. Beaudouin E. Flabbée J. et al.Thresholds of clinical reactivity to milk, egg, peanut and sesame in immunoglobulin E-dependent allergies: evaluation by double-blind or single-blind placebo-controlled oral challenges.Clin Exp Allergy. 2003; 33: 1046-1051Crossref PubMed Scopus (174) Google Scholar Our immunoblot experiments detected serum-specific IgE to the oleosins contained in sesame oil. The sera of our patients also displayed a higher IgE-reactivity to other liposoluble proteins not yet characterized (Fig 1, D). Like oleosins, such lipoproteins are hydrophobic, and because they can not be solubilized in normal saline, they are not present in commercial extracts. Our data suggest that patients with histories of immediate reactions to sesame products and positive results in immediate-reading contact tests with sesame oil should be instructed to avoid all sesame products, including oil. However, further studies in larger samples are needed to confirm the usefulness of this immediate-reading contact test and to validate such advice.