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The prevalence of sesame allergy is increasing in European countries. Cases of severe allergy lack any evidence of specific immunoglobulin (Ig)Es by prick tests and CAPSystem-FEIA. The reasons for this negativity are unknown. In 32 patients displaying immediate symptoms such as anaphylactic shock, asthma, urticaria, angioedema, sesame allergy was diagnosed by double-blind placebo-controlled food challenge (DBPCFC) or convincing clinical history. However, 10 patients had negative prick tests and CapSystem-FEIA. The specificity of IgEs was further investigated by enzyme-linked immunosorbent assay (ELISA), isoelectrofocalisation (IEF)-blotting, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) blotting using total sesame extracts and purified fraction of oil bodies. Monospecific rabbit antibodies directed to two oleosin isoforms (15 and 17 kDa) were used. By ELISA, white sesame seed extract allowed the detection of higher levels of IgE than brown sesame extract. In all sera, numerous bands binding IgEs were detected by IEF or SDS-PAGE. In reducing conditions, two bands (15-17 kDa), could be separated from 2S albumin. Oleosins, present in oil bodies fractions, were recognized by IgEs from all sera. Oleosins are major allergens of sesame seeds and may be relevant to severe anaphylaxis. Falsely negative prick tests could be due to the lack of oleosins in presently available extracts, or to the fact that epitopes might be buried in the inner molecule. Detection tests currently used to identify sesame allergens based on sesame vicillins or other storage proteins could be insufficient for the detection of sesame seed contamination. Oleosins have been named Ses i 4 (17 kDa) and Ses i 5 (15 kDa), in accordance with the IUIS Nomenclature Committee.
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Original article
Identification of oleosins as major allergens in sesame seed allergic
Food allergy to sesame has been observed in children and
in adults in different countries including Israel, Japan,
and Europe (1–5). Anaphylaxis is often severe (6–8). The
prevalence is increasing in European countries and could
represent 2–4% of total food allergies (9, 10). Sesame is
among the 12 allergens requiring labelling on food
products (11).
The major allergen of sesame seeds has already been
described. Ses i 1 (9 kDa) is a member of 2S albumin
family (12) and recognized by all the patients studied
(n¼10). More recently, Beyer et al. (13) identified two
additional sesame allergens: Ses i 2 (7 kDa) and Ses i 3
(45 kDa), which are a subunit of 2S albumin and a 7S
vicilin-like globulin, respectively. A 14 kDa protein
belonging to the 2S albumin family was recognized by
22 of the 24 sera used (13). Numerous other allergens
have been observed by two-dimensional electrophoresis
followed by immunoblotting (14).
Cases of anaphylaxis have been reported despite
negative prick tests and absence of specific immuno-
globulin (Ig)Es (15, 16), where the authors suggested
that the anaphylaxis was IgG-mediated. Other data
have confirmed a potent immunogenicity of sesame
seeds eliciting a polyisotypic response, supporting this
assumption (17).
The aim of this study was to thoroughly investigate 32
sera from patients allergic to sesame, part of them
displaying no evidence of allergen-specific sensitization
by prick tests and CAP-FEIA. Enzyme-linked immuno-
sorbent (ELISA) tests, immunoblotting after isoelectrofo-
calisation (IEF), and sodium dodecyl sulfate
polyacrylamide gel electrophoresis (SDS-PAGE) electro-
Background: The prevalence of sesame allergy is increasing in European coun-
tries. Cases of severe allergy lack any evidence of specific immunoglobulin (Ig)Es
by prick tests and CAPSystem-FEIA. The reasons for this negativity are un-
Methods: In 32 patients displaying immediate symptoms such as anaphylactic
shock, asthma, urticaria, angioedema, sesame allergy was diagnosed by double-
blind placebo-controlled food challenge (DBPCFC) or convincing clinical his-
tory. However, 10 patients had negative prick tests and CapSystem-FEIA. The
specificity of IgEs was further investigated by enzyme-linked immunosorbent
assay (ELISA), isoelectrofocalisation (IEF)-blotting, and sodium dodecyl sulfate
polyacrylamide gel electrophoresis (SDS-PAGE) blotting using total sesame
extracts and purified fraction of oil bodies. Monospecific rabbit antibodies
directed to two oleosin isoforms (15 and 17 kDa) were used.
Results: By ELISA, white sesame seed extract allowed the detection of higher
levels of IgE than brown sesame extract. In all sera, numerous bands binding
IgEs were detected by IEF or SDS-PAGE. In reducing conditions, two bands
(15–17 kDa), could be separated from 2S albumin. Oleosins, present in oil
bodies fractions, were recognized by IgEs from all sera.
Conclusion: Oleosins are major allergens of sesame seeds and may be relevant to
severe anaphylaxis. Falsely negative prick tests could be due to the lack of
oleosins in presently available extracts, or to the fact that epitopes might be
buried in the inner molecule. Detection tests currently used to identify sesame
allergens based on sesame vicillins or other storage proteins could be insufficient
for the detection of sesame seed contamination. Oleosins have been named Ses i
4 (17 kDa) and Ses i 5 (15 kDa), in accordance with the IUIS Nomenclature
V. Leduc
, D. A. Moneret-Vautrin
J. T. C. Tzen
, M. Morisset
L. Guerin
, G. Kanny
Allerbio Laboratory (R and D), Varennes en
Argonne, France;
Department of Internal Medicine,
Clinical Immunology and Allergology, University
Hospital, Nancy Cedex, France;
Graduate Institute
of Biotechnology, National Chung-Hsing University,
Taichung, Taiwan
Key words: food allergy; oil bodies; oleosins; sesame
Denise-Anne Moneret-Vautrin MD, Pr
Department of Internal Medicine, Clinical
Immunology and Allergology
University Hospital
29 avenue du Marchal de Lattre de Tassigny
54035 Nancy Cedex
Accepted for publication 22 September 2005
Abbreviations: IEF, isoelectrofocalisation; pNPP, p-nitrophenyl-
phosphate; CNBr, cyanogen bromide; NC, nitrocellulose; SPT, skin
prick test.
Allergy 2006: 61: 349–356 Copyright Blackwell Munksgaard 2006
DOI: 10.1111/j.1398-9995.2006.01013.x
phoresis were carried out with a white sesame (WS) seed
extract and purified oil bodies containing the two
isoforms of oleosins.
Specific IgEs to the oleosin fraction were detected in
almost all sera from subjects allergic to sesame with
positive or negative prick tests and CAP-FEIA. These
results indicate that oleosins represent a new class of
sesame major allergens.
Materials and methods
Patients (n¼32) including 15 children and 17 adults were selected
and determined to exhibit sesame allergy as evidenced by double-
blind placebo-controlled food challenge (DBPCFC), labial test or
clinical history (Table 1). Patients were ranged according to the
tests performed: 23 patients were positive after food challenge (la-
bial test or DBPCFC), four patients did not react to 965 mg and
7 g, and five patients were not tested. Among the 23 patients, six
patients were negative by skin prick tests (SPT) to three varieties of
sesame seeds and to the commercial extract, as well as with the
CAP-FEIA, which was performed twice for each case. One of them
(patient 1) experienced a prelethal shock after the consumption of
an industrial dish containing an artificial flavoring in a matrix of
Mexican sesame oil. Allergy to sesame was very likely in cases 26
and 27, because of anaphylactic episodes related to successive
ingestions of sesame seeds or of food products that may have
contained sesame seeds or sesame oil.
Skin prick tests
The SPT were carried out with three varieties of natural sesame
seeds (white, brown, and black), crushed in saline according to the
technique of prick-in-prick (18) and compared with a commercial
extract (Allerbio, Varennes en Argonne, France). The positive and
negative controls were codein phosphate 9% and saline buffer,
respectively. Criteria for positivity was a wheal diameter equal to
75% of the positive control wheal.
The patientsÕspecific IgE levels were determined by using the
CAPSystem IgE to sesame (f10 Pharmacia, Uppsala, Sweden). Levels
of specific IgE of >0.35 kU/l (classe 1) were considered positive.
Food challenge
The DBPCFC was performed as previously described (19). Briefly,
the progression increased up to a cumulative dose (CD) of 965 mg.
The vehicle used was a stewed apple and the placebo material was
crushed brown-dried toast.
The DBPCFC using cold-pressed sesame oil was tested in nine
patients, successively using 1, 5, and 10 ml volumes. The placebo
was paraffin oil (mineral oil) (20).
Sesame seed extracts
Brown and white sesame (WS) seeds were ground and extracted
(1 : 5, w/v) overnight in sodium bicarbonate 4&at 4C. After
centrifugation, extracts were filtered on a 0.2 lm filter. Protein
content was measured according to the Bradford method with ser-
um albumin as standard. Protein concentrations were 5.5 mg/ml for
brown sesame (BS) and 2.95 mg/ml for WS extract.
Oil bodies were extracted from sesame seeds and subjected to
further purification using the protocol developed by Tzen et al. (21)
including two-layer flotation by centrifugation, detergent washing,
ionic elution, treatment of chaotropic agent (urea 9 M), and
integrity testing with hexane.
Direct ELISA
Specific IgE were assessed by direct ELISA using white and BS
seed extracts. The ELISA plates (Immulon 2; Thermo Lab sys-
tems, Franklin, MA, USA) were coated with white or BS seed
extracts (10 lg/ml in carbonate buffer, pH 9.6) at 4C overnight.
Plates were washed with phosphate-buffered saline (PBS) con-
taining 0.05% (v/v) Tween 20 (PBS-T) and blocked with 0.5% (w/
v) gelatin in PBS-T at 37C for 1 h. Plates were incubated at 37C
for 2 h with 100 ll per well of patient sera diluted 1 : 5 in blocking
buffer. After three washes, an alkaline phosphatase-coupled affin-
ity purified goat antihuman IgE antibody (KPL, Gaithesburg,
MD, USA) diluted 1 : 1000 in blocking buffer was used to detect
bound IgE. After 2-h incubation at 37C, plates were washed three
times and the color reaction was started with p-nitrophenylphos-
phate (pNPP) in diethanolamin buffer (pH 9.5). The absorbance
was determined at 410 nm (A410 nm). All determinations were
carried out in duplicates. Positive absorbance was defined as the
mean background absorbance ± 3 SD. A Dactylis glomerata
pollen extract and a grass pollen-sensitized human serum (CAP-
FEIA g3 500 kU/l) were used as the standard.
Isoelectric focusing
Isoelectric focusing (IEF) was performed on 1.5% agarose gel with
2.6% ampholytes 3-10 (Serva, Heidelberg, Germany). Samples of
160 lg/cm were applied on the anodic part of the gel. After focus-
ing, the gel was submitted to a 10 min pressure blot onto cyanogen
bromide (CNBr)-activated nitrocellulose (NC; 22).
The SDS-PAGE was performed on a 12% acrylamide gel with a 6%
stacking gel in a Tris-Tricine buffer (23). Extracts were diluted in
20 mM Tris-HCl, pH 6.8, containing 2% (w/v) SDS and brom-
phenol blue. In reducing conditions, 1% (w/v) dithiothreitol (DTT)
was added to the sample buffer and samples were incubated for
10 min at 95C before application on the gel. Proteins of 20 lg/cm
were applied for blotting and 2 lg per lane for silver staining.
Electrophoresis was performed at 15C at 40 mA for 1 h. After
electrophoresis, the gel was electroblotted onto CNBr-activated NC
or silver-stained according to Rabilloud et al. (24).
The IEF or SDS-PAGE strips were blocked in 2% polyvinyl-
pyrrolidone (PVP) in Tris-buffered saline (TBS) containing 0.1%
(v/v) Tween 20 (TBS-T) for 1 h. Blots were then incubated at
room temperature overnight with individual serum diluted 1 : 5 in
blocking buffer. After three washes in TBS-T, blots were incu-
bated with alkaline phosphatase-labeled antihuman IgE in
blocking buffer (1/2000) for 6 h. After three washes in TBS-T,
IgE-binding was revealed using NBT/BCIP (KPL). For the
detection of oleosins, NC strips were incubated with polyclonal
Leduc et al.
monospecific rabbit antisesame oleosin (15 or 17 kDa) antiserum
(1 : 2000 dilution; 25). Rabbit IgG were detected by antirabbit
IgG conjugated with alkaline phosphatase (1/10 000 dilution;
Sigma-Aldrich, St Louis, MO, USA) in blocking buffer. After
washing, color development was performed by incubating the
strips in Tris, NaCl, MgCl
buffer containing 0.33 mg/ml nitro-
blue tetrazolium and 0.165 mg/ml 5-bromo-4-chloro-indolyl
phosphate at room temperature in the dark until a sufficient
coloring occurred. The reaction was stopped by rinsing the
membrane in water.
Table 1. Clinical characteristics of 32 patients with sesame allergy
ID Sex
(years) Symptoms
Prick test
DBPCFC/LT to sesame seeds (S) and/or oil (O)
CE Varieties DBPCFC LT (grade)
1 M 18 RAS Neg B: neg/W: neg/b: neg <0.35 O (15 ml): rash, asthma/S (100 mg): urticaria
2 F 63 RAS to 162 mg ND B: neg/W: neg/b: neg <0.35 S (965 mg): systemic reaction
3 F 9 nf AS Neg B: neg/W: neg/B: neg <0.35 O (8 ml): late onset erythema
4 M 44 AS Neg B: neg/W: neg/B: neg <0.35 O (5 ml): AS/S (200 mg): flush, facial erythema
5 M 54 AS Neg B: neg/W: neg/b: neg <0.35 O (0.7 ml): generalized erythema, abdominal pain
6 M 33 SR Neg B: neg/W: neg/b: neg <0.35 S (7 g): urticaria
7 M 23 AS Neg B: neg/W: neg/b: neg 5.11 O (1 ml): AS/S (265 mg): urticaria, angioedema
8 F 25 Asth Neg B: neg/W: neg/b: neg 0.51 O (20 ml): palpebral erythema, abdominal
pain/S (965 mg): erythema, abdominal pain
9 F 4.5 Asth 11 mm B: 20 mm/W: 7 mm
/b: 11.5 mm
44 S: Grade 3
10 F 17 SR ND B: neg/W: 2 mm/b: 1 mm 4.3 O (16 ml): negative/S (965 mg): urticaria
11 M 3 Asth ND B: 17.5 mm/W: 4 mm
/b: 11.5 mm
76.2 S: Grade 3
12 M 6 Asth ND B: 0.5 mm/W: 2 mm
/b: 2 mm
9.01 S (7 g): abdominal pain, cough and wheezing
13 M 36 AS 1.5 mm B: 5 mm/W: 6.5 mm
/b: nd
<0.35 S (7 g): generalized prurit is erythema S: Grade 1
14 F 3 AD ND B: 13 mm/W: 8 mm
/b: 11 mm
8.26 S (965 mg): exacerbation of AD
15 M 13 SR ND B: 8.5 mm/W: 17 mm
/b: 15.5 mm
13.1 S: Grade 2
16 M 4 Asth ND B: 10 mm/W: 8 mm
/b: 9.5 mm
40 S: Grade 3
17 M 32 AS ND B: 10 mm/W: nd/b: nd <0.35 O: Grade 3
18 F 10 AO 8 mm B: 12.5 mm/W: 5.5 mm
/b:13.5 mm
16.5 S (965 mg): urticaria, wheezing, and vomiting
19 M 4 SR ND B: 8.5 mm/W: 18 mm
/b: 10 mm
4.59 O (6 ml): negative
20 M 47 AS ND B: 9 mm/W: 6 mm
/b: 6 mm
ND S (6 mg): generalized pruritis, erythema on
the neck
21 M 11 Asth ND B: 8.5 mm/W: 6 mm
/b: 4.5 mm
20.5 S (2 g): asthma
22 M 22 Asth 3.5 mm B: 3 mm/W: 4 mm/b: nd 13.2 S (10 g): asthma, erythema
23 M 7 Asth ND B: 13 mm/W: 11 mm
/b: 12 mm
>100 S (7 g): abdominal pain, vomiting, conjunctivitis,
S: Grade 2
24 M 4 Vom ND B:12.5 mm/W: 14.5 mm
/b:7 mm
15.8 S (7 g): negative
25 M 4 SR ND B: 3 mm/W: 12.5 mm
/b:15 mm
>100 ND
26 F 70 AO ND B: neg/W: neg/b: neg <0.35 ND
27 F 31 SR Neg B: neg/W: neg/b: neg <0.35 ND
28 F 26 RAS ND B: neg/W: neg/B : neg <0.35 S (965 mg): negative
29 M 4 SR ND B: neg/W: neg/b: neg <0.35 S (7 g): negative
30 M 12 AO ND B: 3.5 mm/W: 5.5 mm
/b: 5.5 mm
0.41 S (7 g): negative
31 M 21 AO 6.5 mm B:13.5 mm/W: 15.5 mm
/b:14 mm
4.58 ND
32 M 32 AO, U ND B: 7 mm/W: 10 mm
/b: 9 mm
<0.35 ND
RAS, recurrent anaphylactic shock; nf, near fatal; AS, anaphylactic shock; SR, systemic reaction; Asth, asthma; AD, atopic dermatitis; AO, angioedema; Vom, vomiting; LT, labial
test; B, brown; W, white; b, black; M, male; F, female; Neg, negative; ND, not detectable; DBPCFC, double-blind placebo-controlled food challenge; IgE, immunoglubulin E.
Sesame oleosins are relevant major allergens
Clinical symptoms were of immediate type – anaphylactic
shock: seven, recurrent anaphylactic shock: three, systemic
reaction: seven, asthma: eight, angioedema: five, and
vomiting: one. A single patient had atopic dermatitis.
Twenty-seven patients had DBPCFC or labial tests. Four-
teen of 32 DBPCFC to seeds were positive and six of 14 to
oil. Labial tests to seeds were positive in five of five patients
and one of one to oil. Five patients were not challenged
according to the severity of the clinical symptoms. Ten of
32 patients (with positive labial test or DBPCFC in seven
cases), showed negative SPTs to all sesame extracts and no
detectable specific IgE by CAP-FEIA, confirming the
difficulty of sesame seed allergy diagnosis.
Specific IgE
Direct ELISAs were performed to assess the level of
patient-specific IgE to sesame seed by comparing WS and
BS extracts. Whereas ImmunoCAP were found negative
in 13 cases, nine patient sera displayed IgE-binding to WS
and BS extracts by ELISA. White sesame seed extract was
used for the following studies.
IEF immunoblotting. The IEF separation of WS extract
followed by immunoblotting showed numerous bands
recognized by serum IgE of all patients, even from those
with negative CAP-FEIA System (Fig. 1). The isoelectric
points of the bands ranged from 4.5 to 8.5.
SDS-PAGE immunoblotting. White sesame extract was
separated by SDS-PAGE under nonreducing (Fig. 2) or
reducing conditions (Fig. 2). Under nonreducing condi-
tions, allergens were identified migrating between 43 and
67 kDa and between 15 and 17 kDa (Fig. 2). Under
reducing conditions, the silver staining revealed that the
15–17 kDa band, observed in the nonreducing condi-
tions, dissociated into a smaller molecule of 9 kDa,
corresponding to the 2S albumin large subunit (Fig. 3).
However, a doublet located at 15 and 17 kDa was still
observed after immunoblotting (Fig. 3), which was pre-
sumably oleosin isoforms (Ole).
To prove that oleosins are major allergens, SDS-PAGE
immunoblotting of purified oil body fraction (Fig. 4) was
performed. The results showed three major bands
between 15 and 17 kDa corresponding to oleosins
isoforms, as detected by rabbit monospecific anti-
15 kDa and 17 kDa oleosin.
Immunoblots showed that 29 over 32 sera have specific
IgE to the 15.5 and 17 kDa oleosins. The IgE-binding to
both oleosin isoforms was much stronger in case 1 who
exhibited a prelethal shock to a mixture of flavoring
containing a Mexican sesame oil.
The IgE-dependent sensitization to foods may not neces-
sarily coincide with positive prick tests to commercial
extracts, because a maximum of diagnostic sensitivity (i.e.
100%) is difficult to achieve. However, the possibility of
Figure 1. Specificity of immunoglobulin (Ig)E of the 32 patient sera on sesame extract separated by isoelectrofocalisation (IEF)
followed by immunoblotting. On the left, isoelectric point markers and sesame extract stained by Coomassie Brilliant Blue. All sera
were diluted 1 : 5 in blocking buffer (C: control with blocking buffer).
Leduc et al.
falsely negative SPT is often linked to the nature of the
food, and is characteristic of aqueous fruit and vegetables
(26, 27). Extracts of seeds are currently the most efficient
reagents as they are directly related to the concentration
of proteins in the seeds. With this in mind, the fact of no
evidence of positivity of SPT to three natural varieties of
sesame seeds is rather surprising. As sesame seeds are
crushed in a saline solution, we raised the hypothesis of
the presence of hydrophobic allergens that are insoluble
in saline.
Specific IgEs were detected by ELISA and binding of
IgE to numerous proteins were demonstrated after
immunoblotting of IEF gels. Applying both techniques,
the sesame seed proteins were not denatured. Conform-
ational epitopes may be detected, which might otherwise
escape recognition by the CAP-FEIA, where the coupling
procedure could alter these epitopes.
The comparison of the protein profiles on SDS-PAGE
in both reducing and nonreducing conditions revealed
several groups of allergens. The first group consisted of
Figure 2. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting of sesame seed extract. Silver-
stained gel in nonreducing conditions and specificity of immunoglobulin (Ig)E of the 32 patient sera (1–32). All sera were diluted 1 : 5
in blocking buffer (C: control with blocking buffer).
Figure 3. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting of sesame seed extract. Silver-
stained gel in reducing conditions and specificity of immunoglobulin (Ig)E of the 32 patient sera (1–32). All sera were diluted 1 : 5 in
blocking buffer (C: control with blocking buffer).
Sesame oleosins are relevant major allergens
11S globulins that represent 60–70% of the total seed
proteins (28). Each of the 11S globulin isoforms consists
of an acidic subunit (30–40 kDa) and a basic subunit (20–
25 kDa) linked by a disulfide bond (29). Group 2 is the
major soluble protein, 2S albumin, constituting approxi-
mately 15–25% of the total sesame proteins (30). The two
2S albumin isoforms consist of a small subunit (4 kDa)
and a large subunit (9 kDa), linked by a disulfide bond.
Under nonreducing conditions, oleosins migrate at the
same molecular weight as 2S albumins (15–17 kDa). The
third group of two 7S globulin isoforms of 55–60 kDa,
represents 1–2% of the total proteins: they have been
identified as minor constituents in protein bodies (31). In
contrast to 11S globulin and 2S albumin, 7S globulin is a
single polypeptide, recognized by nearly all the patientÕ
Oil bodies are discrete spherical organelles that are also
named lipid bodies, or oleosomes and their storage lipids
are mainly composed of triacylglycerols (TAGs) in most
seeds. The abundant protein referred to as oleosins, which
represent 80–90% of total oil body proteins, corresponds
to only 1–2% of total seed proteins. Three different
oleosins, 17, 15.5 and 15 kDa have been described (32),
and 17 and 15 kDa oleosins have been sequenced (Fig. 5).
These non glycosylated proteins are present at the surface
of oil bodies and play a structural role to stabilize the
organelles during desiccation of the seed by preventing
coalescence of the oil. In this study, we were able to
identify oleosins in oil bodies that were recognized by
IgEs from all patient sera. The intensity of antibody
binding is striking in case 1 (anaphylactic shock after
ingestion of sesame oil), leading us to suspect that the
majority of oleosins remains residually present in oil and
is probably not denatured, as sesame oil is only cold-
pressed. The specific risk of sesame oil in allergic
responses has been pointed out previously (20, 33).
Indeed, patients can react by anaphylactic shock to only
a few milliliters of sesame oil (20). Other oils such as
peanut or soybean oil do not exhibit such severe
reactions, even in highly sensitized subjects allergic to
peanuts or to soybeans. Interestingly, the presence of
oleosin in peanut oil has been shown and the allergenicity
of a recombinant peanut oleosin has been established
Figure 4. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) immunoblotting of purified sesame seed oil bodies.
Silver-stained gel and immunoblot revealed with immunoglobulin (Ig)E of patient sera (1–32). Lanes: (A) monospecific polyclonal
rabbit antibody (Ab) to 15-kDa oleosin; (B) monospecific polyclonal rabbit Ab to 17-kDa oleosin; (C) control with blocking buffer.
Figure 5. Amino acid sequences of the 17 and 15 kDa sesame oleosins, respectively Ses i 4 and Ses i 5. The single-letter amino acid
code is used. A dash indicates a gap introduced for the purposes of alignment. Ô*Õmeans that the residues in the column are identical in
both sequences in the alignment; Ô:Õmeans that conserved substitutions have been observed.
Leduc et al.
In conclusion, we have identified oleosins as new
sesame seed major allergens, present in seeds and
presumably in oil. The IgEs from all sesame allergic
patients studied consistently bound to oleosins. To
explain the negativity of SPT to natural sesame, a first
hypothesis could be that, in these six patients, the
amount of specific IgEs might be predominantly directed
to oleosins. The negativity of SPT to natural varieties of
seeds could indicate that oleosins are not solubilized in
saline, or, alternatively that their epitopes are hindered
by the association of oleosins to the TAG, or in the
inner part of the molecules, masked by folding of the
tertiary structure. If such is the case, the negativity of
SPT to natural varieties crushed in saline could imply
that these patients have IgEs directed toward epitopes of
oleosins buried in the inner part of the molecules.
However, the results of ELISA do not support this
hypothesis. Neither the level of specific IgE to oil bodies,
nor the ratio of IgE to oil bodies/total sesame seed
differs in patients with negative or positive PT to sesame
seeds (data not shown). This issue cannot be elucidated
at present.
Two oleosin (17 and 15 kDa) sequences are known
(Fig. 5). According to the IUIS Nomenclature, we
submitted these oleosins as Ses i 4 and Ses i 5, respect-
ively. They may characterize severe anaphylaxis without
evidence of specific IgEs by the present methods of
Some homology between oleosins of different species
has been found for a Chinese spice shiso (Perilla
frutescens, 75% identity) and for carrot oleosin (64% of
identity). Sequence comparison (BLAST) with peanut
and soybean oleosins showed lower levels: 56% and 51%.
Higher levels of identity can be reached if the sequence is
restricted to the central part of oleosins. This domain
whose sequence is conserved, is highly hydrophobic and
interacts with the lipids. Moreover, this central domain
does not present any trypsin cleavage site.
This study supports the obvious need to improve the
quality of extracts of sesame for diagnosis. Moreover, it is
noteworthy that detection tests for masked sesame
allergens are based on vicilins (35). The fact that oleosins
are major allergens supports the proposition of oleosins
as new markers of masked allergens.
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Leduc et al.
... The family of 11S globulins or legumins (cupin superfamily) represents 60-70% of total protein fraction of sesame seeds. The second group is the 2S albumin family (prolamin superfamily), major soluble proteins, representing approximately 15-25% of the total protein content, while only 1-2% of seeds proteins are composed of two 7S globulin or vicilin (cupin superfamily) isoforms (Leduc et al. 2006;Tai et al. 2001). In sesame, the high contents of 2S albumins, legumins and vicilins in relation to total protein seem to be correlated with an increased allergic elicitation risk (Costa, Bavaro, et al. 2022). ...
... Oleosins are small proteins of 16-20 kDa, representing only 1-2% of total seed proteins, but 80-90% of total oil body proteins (Leduc et al. 2006). Oil bodies consist of lipid droplets usually distributed in oil seeds as a storage form of triglycerides within the cotyledon cells (Barre et al. 2018). ...
... Oil bodies consist of lipid droplets usually distributed in oil seeds as a storage form of triglycerides within the cotyledon cells (Barre et al. 2018). These non-glycosylated proteins are present on the surface of oil bodies and appear to have a structural stabilizing role during the desiccation of the seed, as they prevent the coalescence of the oil, interacting with the lipid and phospholipid fractions of the lipid bodies (Leduc et al. 2006). They possess a hydrophobic α-helical hairpin core, anchoring the protein to the lipid monolayer surrounding the protein body. ...
Sesame is an allergenic food with an increasing allergy prevalence among the European/USA population. Sesame allergy is generally life-persisting, being the cause of severe/systemic adverse immune responses in sesame-allergic individuals. Herein, clinical data about sesame allergy, including prevalence, diagnosis, relevance, and treatments are described, with focus on the molecular characterization of sesame allergens, their cross-reactivity and co-sensitization phenomena. The influence of food processing and digestibility on the stability/immunoreactivity of sesame allergens is critically discussed and the analytical approaches available for their detection in foodstuffs. Cross-reactivity between sesame and tree nuts or peanuts is frequent because of the high similarities among proteins of the same family. However, cross-reactivity phenomena are not always correlated with true clinical allergy in sensitized patients. Data suggest that sesame allergens are resistant to heat treatments and digestibility, with little effect on their immunoreactivity. Nevertheless, data are scarce, evidencing the need for more research to understand the effect of food processing on sesame allergenicity modulation. The demands for identifying trace amounts of sesame in foods have prompted the development of analytical methods, which have targeted both protein and DNA markers, providing reliable, specific, and sensitive tools, crucial for the effective management of sesame as an allergenic food.
... In 2006, Leduc et al. identified oleosins of sesame (Sesamum indicum), Ses i 4, and Ses i 5 as major allergens in a series of 32 patients developing severe anaphylaxis after sesame consumption [6]. To date, seven additional oleosins are recognized by the WHO/IUIS Allergen Nomenclature Sub-Committee (, ...
... Patients (9 adults and one child, mean age = 41.0 ± 17.9 years) were selected because of sesame allergy evidenced by a convincing clinical history to sesame and/or a positive double-blind placebo-controlled food challenge (DBPCFC) to sesame seed and/or oil (Table 1). DBPCFC were performed as previously described [6]. ...
... Sesame oleosins have been reported as allergens, but their IgE reactive epitopes were not yet identified [6,[26][27][28]. In the present study focused on Ses i 4, we assessed the localization of epitopes recognized by sesame-allergic patients' IgE by immunoblotting using recombinant truncated variants coupled to HCA and molecular modeling approaches. ...
Aim of the study Oleosins are allergens implicated in severe anaphylactic reactions after sesame, peanut or hazelnut consumption. However, identifying oleosin allergenic epitopes is hindered by their hydrophobic properties that do not allow analysis in an aqueous solution. Therefore, the present study focused on determining IgE-binding domains of sesame oleosin Ses i 4 using immunoblotting. Patients and methods We relied on sera from ten patients with clinically established allergy to sesame. Immunoblotting coupled to Hydrophobic Cluster Analysis (HCA) approach using a series of recombinant full-length and truncated Ses i 4 variants enabled detection of IgE reactivity domains. Results and conclusion The data showed that IgE-binding sequences were located in the hydrophobic domain of the Ses i 4. The three IgE-binding segments were in proximity but on the flanks of the central-most hydrophobic segment. Further, their amino acid sequences are highly conserved in Ses i 4-homologs from different allergenic sources. Therefore, unlike most clinical immunoassays, Western blotting may be helpful for in vitro detection of oleosin IgE reactivity.
... Western blotting results showed that the allergenic reaction of some patients (patients 16, 23, 24, 25, 26, and 27) was caused by 11S globulin, which aligned with a previous report. 12 Oleosin is a major allergen in sesame and has a high rate of IgE recognition. In this study, the IgE recognition rate was about 80%. ...
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Sesame can trigger a systemic allergic reaction. In the present study, we investigated the responses of the structure and IgE binding of sesame allergens to different roasting treatments (120, 150, and 180 °C for 5 to 30 min). We analyzed the tryptic digestion peptides using a label-free mass spectrometry method. The total amount of soluble proteins in sesame was significantly reduced by roasting at 180 °C, followed by 150 °C. Ses i 1 was the most stable protein during processing as it still possessed a higher protein abundance compared to other allergens after roasting under 180 °C. The most unstable allergens were Ses i 4 and Ses i 7, which suffered severe protein degradation at 180 °C. Roasting at 180 °C remarkably increased the secondary structure content of α-helices but decreased that of β-sheets, whereas roasting at 120 and 150 °C had a limited effect on the secondary structure of sesame proteins. Moreover, serum pool Western blot analysis showed that the main allergens were oleosin of Ses i 4 and Ses i 5. The IgE-binding ability of sesame allergens was significantly decreased under 180 °C roasting, as well as the solubility of sesame proteins, which showed remarkable congruence in changes. Relative quantification results indicate that individual sesame allergens respond differently to the roasting process. In general, sesame allergens are unstable under roasting treatment. Therefore, the allergenic potential of sesame allergens may be minimized by selecting appropriate parameters during processing.
Background: Few studies have focused on food allergies in the elderly, even though it may persist or appear de novo. Methods: We reviewed data for all cases of food-induced anaphylaxis in people age ≥ 60 reported to the French "Allergy Vigilance Network" (RAV) between 2002 and 2021. RAV collates data reported by French-speaking allergists regarding cases of anaphylaxis graded II to IV according to the Ring and Messmer classification. Results: In total, 191 cases were reported, with an even sex distribution and mean age was 67.4 years (range 60 to 93). The most frequent allergens were mammalian meat and offal (31 cases, 16.2%), often associated with IgE to α-Gal. Legumes were reported in 26 cases (13.6%), fruits and vegetables in 25 cases (13.1%), shellfish 25 cases (13.1%), nuts 20 cases (10.5%), cereals 18 cases (9.4%), seeds 10 cases (5.2%), fish 8 cases (4.2%) and anisakis 8 cases (4.2%). Severity was grade II in 86 cases (45%), grade III in 98 cases (52%) and grade IV in 6 cases (3%) with one death. Most episodes occurred at home or in a restaurant and in most cases adrenaline was not used to treat the acute episode. Potentially relevant cofactors such as beta-blocker, alcohol or non-steroidal anti-inflammatory drug intake were present in 61% of cases. Chronic cardiomyopathy, present in 11.5% of the population, was associated with greater, grade III or IV reaction severity (OR 3.4; 1.24-10.95). Conclusion: Anaphylaxis in the elderly has different causes to younger people and requires detailed diagnostic testing and individualized care plans.
We have developed a magnetic separation-based immunocolorimetric assay to detect sesame allergens. Sesame monoclonal antibody (Ab) was modified onto gold nanoparticles (AuNPs) to create signal probes (AuNPs-Ab), and sesame allergens (SA) were attached to carboxyl-functionalized magnetic polystyrene microspheres (MPMs) to act as capture probes (MPMs-SA). Based on the competition format, the capture probes competed with the sesame allergens in the sample to bind the corresponding signal probes. When sesame allergens were present, two immune complexes (AuNPs-Ab@MPMs-SA and AuNPs-Ab@SA) were formed. The immune complex AuNPs-Ab@SA was used to quantify the sesame allergens in the sample. This immunoassay had a detection linear range from 50 to 800 μg L-1 with a limit of detection (LOD) of 45.53 μg L-1. Based on the optimized conditions, the recovery of sesame allergens in bread, biscuit, almond beverage, and energy bar samples was between 82.50% and 116.67%. The LODs for the bread, biscuit, almond beverage, and energy bar samples were 0.36, 0.36, 0.27, and 0.55 mg kg-1, respectively.
Sesame allergy is a serious public health problem and is mainly induced by IgE-mediated reactions, whose prevalence is distributed all over the world. Sesame has been included on the priority allergic food list in many countries. This review summarizes the mechanism and prevalence of sesame allergy. The characteristics, structures and epitopes of sesame allergens (Ses i 1 to Ses i 7) are included. Moreover, the detection methods for sesame allergens are evaluated, including nucleic-acid, immunoassays, mass spectrometry, and biosensors. Various processing techniques for reducing sesame allergenicity are discussed. Additionally, the potential cross-reactivity of sesame with other plant foods is assessed. It is found that the allergenicity of sesame is related to the structures and epitopes of sesame allergens. Immunoassays and mass spectrometry are the major analytical tools for detecting and quantifying sesame allergens in food. Limited technologies have been successfully used to reduce the antigenicity of sesame, involving microwave heating, high hydrostatic pressure, salt and pH treatment. More technologies for reducing the allergenicity of sesame should be widely investigated in future studies. The reduction of allergenicity in processed sesames should be ultimately confirmed by clinical studies. What’s more, sesame may exhibit cross-reactivity with peanut and tree nuts.
Background Sesame allergy has been characterized in the Middle East for some time, but has become more widely recognized as foods containing sesame and sesame seeds have become more widely available in Australia, Europe, and North America. With the passage of the Food Allergy Safety, Treatment, Education, and Research (FASTER) Act in 2021, the United States will join other countries in identifying sesame as a major food allergen and will require sesame to be labeled as a food allergen beginning in 2023. Objective To review the literature related to sesame allergy as an increasingly recognized food allergen around the world. Data sources English-language articles obtained through PubMed searches with relevance to sesame allergy. Study selections Articles were included using the search terms “sesame allergy” and “sesame seed allergy” Results A total of 69 relevant articles were selected regarding sesame allergy relating to its prevalence, clinical presentation, natural history, allergenic epitopes, diagnosis, and treatment. Conclusion In recent decades significant gains have been made in determining prevalence and natural history of sesame allergy. With increased recognition and prevalence come the need for reliable methods of identification of sesame allergy as well as approaches to management.
A highly sensitive smartphone-integrated fluorescence quenching immunochromatographic assay (FQICA) for the detection of sesame allergen was proposed. Sesame antibodies were adsorbed on the surface of the gold nanoparticles to form fluorescent acceptors (AuNPs-Ab). Ovalbumin (OVA) protein was labeled with quantum dots (QDs) to form signal probes (QDs-OVA), which were coated on the C-line of the assay strips. A mixture of QDs-OVA and sesame protein was coated on the T-line of the strip. For FQICA, the concentration of the analyte was positively correlated with the fluorescence signal. The developed FQICA had high sensitivity for the detection of sesame protein, and its visual LOD was 80 μg/L and the quantitative LOD was 40 μg/L. In addition, the method had high specificity, except for a small cross-reaction between sesame and walnut. The visual LODs in bread, ham, and biscuits were 640 μg/L. The quantitative LODs were 320 μg/L for biscuits and 640 μg/L for bread and ham. Comparing the developed FQICA with a commercial ELISA kit, the recoveries of sesame protein in both methods were between 80% and 120%.
Citrus fruits of industrial interest include lemons, oranges, mandarins, grapefruits, clementines, limes and other commercially minor ones. A huge amount of agricultural waste is generated yearly all over the globe by citrus fruit industry. The wastes from these productions may be, however, of great nutritional and economic value for their chemical composition, due to their abundance of diverse functional compounds. Citrus fruits are extensively cultivated in any part of the world, therefore recovery and reuse of their waste is mandatory to reduce the environmental impact, to promote circular economy, to reduce waste of functional compounds and to obtain value-added products by economically advantageous processes. Graphical Abstract: The bioactive compounds of Citrus wastes.
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Oil bodies of plant seeds contain a matrix of triacylglycerols surrounded by a monolayer of phospholipids embedded with alkaline proteins termed oleosins. Triacylglycerols and two oleosin isoforms of 17 and 15 kDa were exclusively accumulated in oil bodies of developing sesame seeds. During seed development, 17 kDa oleosin emerged later than 15 kDa oleosin, but it was subsequently found to be the most abundant protein in mature oil bodies. Phosphotidylcholine, the major phospholipid in oil bodies, was amassed in microsomes during the formation of oil bodies. Prior to the formation of these oil bodies, a few oil droplets of smaller size were observed both in vivo and in vitro. These oil droplets were unstable, presumably due to the lack of steric hindrance shielded by the oleosins. The temporary maintenance of these droplets as small entities seemed to be achieved by phospholipids, presumably wrapped in ER. Oil bodies assembled in late developing stages possessed a higher ratio of oleosin 17 kDa over oleosin 15 kDa and were utilized earlier during germination. It seems that the proportion of oleosin 17 kDa on the surface of oil bodies is related to the priority of their utilization.
In recent decades, significant progress has been made in understanding allergic reactions to foods. The predictive value of skin testing to foods is much better understood now than in the 1970s, and at least one of the in vitro diagnostic techniques may emerge as an additional aid to management (CAP-FEIA, vide infra). The double-blind, placebo-controlled food challenge (DBPCFC) continues to be the only tool able to prove definitively the presence of food allergy (short of anaphylaxis); however, there remains a place for open food challenges. With the simple tools of skin tests and challenges, typical IgE-mediated food allergy can be fairly simply characterized. Unusual complaints related to foods may also be investigated by modification of these techniques. In this article, we provide a practical approach to the use of skin tests and challenges for diagnosis of food allergy. Use of these techniques should minimize patient risk both from diagnostic procedures and from inappropriately restrictive diets.
EDITOR,—Hugh Sampson's editorial on managing peanut allergy omits one important point1: medical identification bracelets should be worn at all times. Unsurprisingly, attention focuses on peanuts,2 but sesame allergy, although less common than peanut allergy, can be every bit as severe. Sesame is used extensively in the food industry, and the seeds present a danger because of their versatility.3 I report here my most recent allergic reaction to sesame. I was looking forward to an evening out with …
The low molecular weight protein fraction from the proteins of sesame seed has been isolated in a homogeneous form and is termed β-globulin or consesamin. The protein has an S°20,w of 2.0 ± 0.1, D20,w of 8 × 10-7 cm2/s, and a partial specific volume of 0.725 mL/g. The intrinsic viscosity of the protein was determined to be 4.1 mL/g. The molecular weight determined by various approaches gives a value of 15000 ± 500, The evaluation of frictional ratios using Stokes radius and other hydrodynamic parameters indicates that the protein is elongated. The secondary structure of the protein indicates it to be rich in α helix. The protein is rich in acidic amino acids, especially glutamic acid, and also hydrophobic amino acids.
Recently, we found sesame to be a major cause of severe IgE-mediated food allergic reactions among infants and young children in Israel. The purpose of this study was to describe the different patterns of sesame sensitivity. We have identified three subgroups among our patients (n = 32). Group I (n = 23, M/F; 14/9) consisted of cases with IgE-mediated sesame allergy. The mean age of the first allergic reaction was 11.7 months. Although the main clinical manifestation was urticaria/angiedema (n = 14, 60%), anaphylaxis was the presenting symptom in seven (30%) patients; all of them were younger than 1 year. Sixteen (70%) were found to be allergic to other foods, and other atopic diseases were identified in 18 (78%) patients. Three patients ‘outgrew’ their allergy within 1–2 years. Group II (n = 2) included cases in whom sesame allergy was ruled out based on a negative skin prick test (SPT) together with a negative open oral challenge. Group III (n = 7) consisted of patients that were found to be SPT positive for sesame as part of a screening for other food allergies. Although sesame products have become fashionable in westernized countries, early exposure may cause sesame to share eventually the same ‘noteriety and fate’ as peanut – a major cause of severe food allergic reactions.
Background: Allergic reactions induced by ingestion of foods containing sesame seeds are a well recognized cause of severe food-induced anaphylaxis. Objective: This study aimed to identify and characterize the clinically most important major allergen of sesame seeds. Methods: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and IgE immunoblotting were performed on sera of 10 patients selected for severe and documented allergic reaction after eating food containing sesame. The major allergen was purified by gel filtration and characterized by isoelectric point (pI), glycosylation and amino acid sequencing. Results: All the patients had positive IgE antibodies and skin prick tests (SPTs) to sesame. The major, clinically most important allergen was a protein with molecular mass of about 9000. It was not glycosylated, the amino acid sequence showed it was a 2S albumin with a pI of 7.3; the small and the large subunits, forming the whole protein, showed pI values of 6.5 and 6.0.
Seed storage proteins commonly comprise various groups of multiple isoforms encoded by gene families. 11S globulin and 2S albumin, conventionally termed α-globulin and β-globulin, are the two major storage proteins and constitute 80–90 % of total seed proteins in sesame (Sesamum indicum L.). Two full-length cDNA clones were sequenced and deduced to encode isoforms of sesame 11S globulin and 2S albumin precursors, respectively. In addition, a full-length cDNA encoding a putative 7S globulin precursor was obtained. The existence of 7S globulin as a minor storage protein in sesame was confirmed by immunodetection. Southern hybridization indicates that all three storage protein genes are present in single or low copy number in the sesame genome. Both northern and western analyses suggest that storage proteins are expressed and deposited into protein bodies later than the initiation of oil body formation in accord with the observation in electron microscopy. Immunogold labeling reveals that all three storage proteins are co-existent in each protein body of sesame seeds, and that 2S albumin and 7S globulin are preferentially located in the peripheral portion of protein bodies.