Inuo et al.
Allergy, Asthma & Clinical Immunology(2022) 18:49
https://doi.org/10.1186/s13223-022-00692-0

Allergy, Asthma & Clinical Immunology
Open Access

CASE REPORTGeneralized allergic reaction
in response to exercise due to strawberrygibberellin‑regulated protein: a case report
Chisato Inuo1* , Fumiko Okazaki2, Rie Shiraki2, Yutaka Tanaka1, Keiko Momma3, Yasuto Kondo4 andHiroshi Narita3,5Abstract
Background: The Rosaceae family includes fruits, such as peach, apple, Japanese apricot, cherry (Prunoideae
subfamily), and strawberry (Rosoideae subfamily). The allergens responsible for Rosaceae fruit allergies have beenreported to include Bet v 1 and profilin, which mainly cause oral symptoms, and lipid transfer protein (LTP). Recently,
gibberellin-regulated protein (GRP) has been identified as an allergen that induces generalized symptoms in peach-,orange-, and plum-related allergies. Most patients with food allergies induced by GRP show allergic symptoms
accompanied by cofactors, such as exercise or drugs. To date, there are very few reports of generalized symptoms
induced by strawberry.
Case presentation: We evaluated the reactivity of strawberry GRP in a 15-year-old boy who was confirmed to havegeneralized symptoms induced by strawberry with exercise using an oral food challenge test (OFCT). The patient’s
serum exhibited a strong positive reaction to strawberry GRP but not to peach GRP or peach LTP. The patient’s
basophils reacted to strawberry and peach GRP but not to peach LTP.
Conclusions: Strawberry GRP may be a causative component for strawberry with exercise-induced generalized
symptoms in this patient. This is the first study to investigate the role of GRP in strawberry with cofactor-induced
allergic symptoms. Further epidemiological and clinical researches are necessary to improve diagnostic andtherapeutic approaches for patients with strawberry allergy.
Keywords: Strawberry, Gibberellin-regulated protein, Fruits, Pollen-food allergy syndrome, Peach
Background
The Rosaceae family includes fruits, such as peach,apple, Japanese apricot, cherry (Prunoideae subfamily),and strawberry (Rosoideae subfamily). The allergens
responsible for Rosaceae fruit allergies have beenreported to include Bet v 1 and profilin, which mainly
cause oral symptoms, and lipid transfer protein (LTP)*Correspondence: cinuo@kcmc.jp
1
Department of Allergy, Kanagawa Children’s Medical Center, 2‑138‑4
Mutsukawa, Minami‑ku, Yokohama, Kanagawa 232‑8555, Japan
Full list of author information is available at the end of the article

and gibberellin-regulated protein (GRP), which cause
systemic symptoms [1].
Strawberries are cultivated and eaten worldwide. Casesof strawberry allergy have been reported previously[2–7]. Three allergens (Fra a 1, 3, and 4) have been
identified for strawberries [4]. Fra a 1 is Bet v 1 homologthat has already lost the immunoglobulin (Ig) E-binding
activities through heat or enzyme treatment. Therefore,a Bet v 1 homolog causes immediate allergy localized in
the oral mucosa; it rarely causes generalized symptoms.
Fra a 4 belongs to the profilin family, which is the mostwidespread allergen throughout the plant. Moreover, theallergens of the profilin family are not heat-stable and are© The Author(s) 2022. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which
permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to theoriginal author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images orother third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit
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to the data.

Inuo et al. Allergy, Asthma & Clinical Immunology(2022) 18:49

vulnerable to gastric digestion. Fra a 3 belongs to the LTP
family. Some studies have reported that Pru p 3 (LTP inpeach) causes generalized symptoms [1]. Interestingly,
a previous report suggested that Fra a 3 is less potent
than peach or apple LTP [5]. To date, there are very few
reports of generalized symptoms induced by strawberry[2, 6, 7].
GRP has been identified as another allergen thatinduces generalized symptoms in peach-, orange-,and plum-related allergies [7–14]. Most patients withfood allergies induced by GRP show allergic symptoms
accompanied by cofactors, such as exercise or drugs[13]. Thus, we evaluated the reactivity of strawberry
GRP in a patient who was confirmed to have generalized
symptoms induced by strawberry with exercise using anoral food challenge test (OFCT).

Case presentation
A 15-year-old boy presented with three episodesof allergic symptoms induced by exercise following
ingestion of certain fruits. First, he had generalized
urticaria induced by exercise after ingesting mixed
fruit with canned peach. Moreover, he had generalized
urticaria and cough induced by exercise after ingesting
yogurt and apple. Furthermore, he had generalized
urticaria and swollen lips induced by walking fast to
school after ingesting strawberries and yogurt. He had
no prior history of allergic symptoms presenting afteringestion of other foods. The patient underwent OFCTs,
which included ingesting 10 fresh strawberries, onecommercially available yogurt cup, one whole canned
peach, or one and a half apples along with aspirin,
followed by a 500-m sprint after 15 min, each on adifferent day. He experienced generalized urticaria after
fruit consumption and exercise but not after eating
yogurt with aspirin and/or exercise. He was diagnosed
with exercise-induced strawberry, peach, and apple
allergies. He had pollinosis, and his specific IgE levels(ImmunoCAP; ThermoFisher Scientific, Waltham, MA)
for Japanese cedar and cypress pollen were 26.4 and9.73 ­UA/mL, respectively, whereas those for birch, alderpollen, and rBet v 1 were normal (< 0.30 ­UA/mL). His
fruit-specific IgE levels, including those for strawberry,peach, apple, rPru p1, rPru p 3, rPru p 4, rMal d 1, andrMal d 3, were normal (Table 1).
We performed a skin prick test with fresh strawberries
using
the
“prick-prick”
procedure.
Histamine
dihydrochloride (10 mg/mL) and saline were used as
positive and negative controls, respectively. The patient
exhibited positive reactions for strawberry (wheal, 4 mm)
and the positive control (wheal, 10 mm) in the prick test
and negative reactions for the negative control (wheal,
0 mm).

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Table 1 Clinical backgrounds of the present patient and control
patients
Present
patient

Controlpatient 1

Controlpatient 2

  Generalized symptoms

+
+

−

−

  Localized symptoms++

Clinical symptoms
Strawberry

Peach  Generalized symptoms

+

+

−

  Localized symptoms

+

+

+

  Generalized symptoms

+

−

−

  Localized symptoms

+

+

+

Apple

sIgE ­(UA/mL)
Strawberry sIgE

< 0.30< 0.300.76

Peach sIgE

< 0.30< 0.30

2.13

Apple sIgE

< 0.30< 0.303.82

Japanese Cedar sIgE

26.4

58.1

78.4

Japanese Cypress sIgE

14.6

11.8

Birch sIgE

< 0.3050.8

Alder sIgE

< 0.3038.4

sIgE specific immunoglobulin E.

For component analysis, we prepared peach GRP
and LTP by immunoaffinity columns using monoclonal
antibodies, as reported previously [10]. Strawberry GRP
was purified using a monoclonal antibody against peach
GRP, which exhibited cross-reactivity to strawberry GRP.
Each purified protein showed a single band on sodium
dodecyl sulfate–polyacrylamide gel electrophoresis
under reducing or non-reducing conditions. The specificIgE levels to each protein were measured by enzymelinked immunosorbent assay (ELISA) with peroxidaselabeled anti-human IgE (SeraCare Life Sciences, Milford,
MA). Data exhibiting absorbance at values 450 nm
over the mean + three standard deviations of those ofnegative controls (four non-allergic individuals) wereconsidered positive. We included control patients withstrawberry, peach, and apple allergies among the patientsof our hospital to evaluate the immunological differencein the reactivity of systemic and local symptoms to
strawberries and peaches. Control Patient 1 had episodic
generalized symptoms after ingesting peaches and mild
oropharyngeal pruritus after ingesting strawberries
without generalized symptoms. Control Patient 2 had
mild oropharyngeal pruritus and swelling of the lips
after ingesting peaches, apples, and strawberries without
presenting generalized symptoms. Differences in theclinical backgrounds and allergen-specific IgEs between
the case patient and controls are shown in Table 1. The

Inuo et al. Allergy, Asthma & Clinical Immunology(2022) 18:49

Page 3 of 5

patient’s serum exhibited a strong positive result tostrawberry GRP but a negative result to peach GRP andpeach LTP. Control Patient 1 exhibited a strong positive
result to peach GRP but not to strawberry GRP or peach
LTP. Control Patient 2 did not react to any component.
These results are shown in Fig. 1.
Basophil activation (BA) was tested using anallergenicity kit (Beckman Coulter, Fullerton, CA), as
previously described [15]. Samples were analyzed using
a FACSCalibur™ cell analyzer with CellQuest software(Becton Dickinson, Franklin Lakes, NJ). Basophils wereidentified based on their forward- and side-scatter
properties, absence of CD3, and presence of CRTH2.
We evaluated allergen-specific BA using serially diluted
components (five concentrations, 0.1–1000 ng/mL of
total protein). We constructed dose-response curves for
BA based on tenfold decreasing concentrations of therespective extracts. The area under the curve (AUC) of
BA was evaluated. The patient’s basophils reacted withstrawberry and peach GRP but not with peach LTP(Fig. 2). The AUCs of BA due to strawberry and peach
GRP were 11,221 and 9507, respectively. Basophils ofControl Patient 2 did not react with these components(highest value: 4.0%). The BA of Control Patient 1 could
not be evaluated.

been performed. The patient’s basophils and serum
reacted with strawberry and peach GRP. Those of control
patients who showed limited perioral symptoms without
generalized symptoms after ingesting strawberries did
not react to strawberry GRP.

Discussion and conclusions

The characters of GRP and cofactors

The summary of the patient and the reactivityof strawberry GRP

This patient was confirmed to have strawberry, peach,and apple allergies using OFCTs. The immunologicalevaluations against strawberry and peach GRP had

Fig. 1 ELISA results for the patient’s serum and the sera of control
patients. The patient’s serum showed a strong positive result for
strawberry GRP. The serum of Control Patient 1 with severe peachallergy exhibited a strong positive result for peach GRP. The serumof Control Patient 2 with localized symptoms induced by peach andstrawberry exhibited a negative result for peach and strawberry GRPs.
The sera of all patients exhibited negative results for peach LTP. ELISA
enzyme-linked immunosorbent assay, GRP gibberellin-regulated
protein, LTP lipid transfer protein

Fig. 2 Basophil activation by strawberry GRP, peach GRP,
and peach LTP extracts. The basophils of the present patient
reacted to strawberry and peach GRPs but not to peach LTP. GRP
gibberellin-regulated protein, LTP lipid transfer protein

Strawberries are eaten raw and in processed foods, suchas jam, yogurt, and cake. Tuppo et al. revealed that peach
GRP is heat-stable [8], which suggests that strawberry
GRP might be heat-stable and induce allergy symptoms
after ingestion of strawberry-containing processed food.
Most patients with sensitization to peach GRP were notsensitized to Rosaceae family pollens, including birch andalder pollen [13]. Additionally, a relationship between
cypress pollen allergy and GRP has been reported [14].
Our patient’s specific IgE levels are consistent with thosereported previously.
This patient had no symptoms after ingestionof strawberries without exercise. He exhibited no
respiratory or cardiological symptoms and had neverexperienced anaphylaxis. The symptoms induced byfruits required a cofactor, such as exercise and/or
aspirin ingestion. Klingebiel et al. showed that BA in
patients allergic to peach GRP with clinical reactions
requiring cofactors was lower than that without cofactor
requirement [14], which is consistent with our patient’s
BA. The low number of positive results in OFCTs
against strawberries in a previous study may be because
no cofactors were added to the OFCTs [6]. Cofactors,
such as exercise, are ones that lower the threshold forallergic reactions to food and increase the likelihoodof a systemic reaction. Thus, in the present case, theInuo et al. Allergy, Asthma & Clinical Immunology(2022) 18:49

sensitization to GRP was discovered after the symptoms
occurred. We hope that strawberry GRP measurement
will become more common to prevent allergic symptoms
from occurring.
The reactivity of peach GRP and LTP

The serum of this patient did not react to peach GRP.
The reaction of some patients’ sera to peach GRP wasmuch weaker than that of BAs in a previous report [14].
Our previous report showed that some patients’ sera
exhibit weaker reactions to native peach GRP than torecombinant peach GRP [10]. The reactivity of peach
GRP in ELISA and BA when assessing peach-induced
generalized symptoms should be further examined.
We could not extract strawberry LTP; therefore, we
could not evaluate the reaction of the present patient’s
serum to strawberry LTP. Reactions to apple LTP (Mald 3) and peach LTP (Pru p 3) in the present patientwere negative. A previous study showed that rFra a 3 (astrawberry LTP) is 73−77% homologous to Mal d 3, andall patients who tested negative for Mal d 3 also tested
negative for rFra a 3 in that study [5]. It is unlikely thatstrawberry LTP contributed to the present patient’s
systemic symptoms.

Page 4 of 5

Funding
This work was supported by JSPS KAKENHI (grant number JP19K14025).
Availability of data and materials
All data generated or analyzed during this study are included in this article.
Further inquiries can be directed to the corresponding author.

Declarations
Ethics approval and consent to participate
The patient and his parents provided written informed consent for this study.
Consent for publication
Written informed consent for publication of the clinical details of the patient
was obtained from the patient and his parent.
Competing interests
The authors declare that they have no competing interests.
Author details
1
Department of Allergy, Kanagawa Children’s Medical Center, 2‑138‑4
Mutsukawa, Minami‑ku, Yokohama, Kanagawa 232‑8555, Japan. 2 Department
of Food Science and Human Nutrition Faculty of Agriculture, Ryukoku
University, 1‑5 Yokotani, Seta Oe‑cho, Otsu, Shiga 520‑2194, Japan.
3
Department of Food Science, Kyoto Women’s University, 35 Kitahiyoshi‑cho,
Imakumano, Higashiyama‑ku, Kyoto 605‑8501, Japan. 4 Departmentof Pediatrics, Fujita Health University Bantane Hospital, 3‑6‑10 Otobashi,
Nakagawa‑Ku, Nagoya, Aichi, Japan. 5 Kyoto College of Nutritional and Medical
Sciences, 18 Setogawa‑cho, Sagatenryuji, Ukyo‑ku, Kyoto, Japan.
Received: 17 November 2021 Accepted: 30 May 2022

Limitations

This study had some limitations. First, tests for allergencomponents in strawberry are not available commercially
and, hence, were not performed in this patient. Second,
it remains unclear whether the primary sensitization to
strawberry GRP was caused by peach or pollen.
Conclusion

Strawberry GRP may be a causative component for
strawberry with exercise-induced generalized symptoms
in this patient. To our knowledge, this is the first study toinvestigate the role of GRP in strawberry with cofactorinduced allergic symptoms. Further epidemiological andclinical researches are necessary to improve diagnostic
and therapeutic approaches for patients with strawberryallergy.
Abbreviations
AUC​: Area under the curve; BA: Basophil activation; ELISA: Enzyme-linked
immunosorbent assay; GRP: Gibberellin-regulated protein; LTP: Lipid transfer
protein; OFCT: Oral food challenge test.
Acknowledgements
We would like to thank Editage (www.​edita​ge.​com) for English language
editing and publication support.
Author contributions
CI and FO designed the study. CI wrote the draft of the manuscript. CI and
FO contributed equally to this work. CI, FO, RS, and YT contributed to datacollection. KM, YK, and HN assisted in data interpretation. All authors have readand approved the final manuscript.

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