Corresponding Author
Enrico SCALA
Clinical and Laboratory MolecularAllergy Unit- IDI- IRCCS, Rome, Italy
via Monti di Creta 104, 00138 - Rome, Italy
Phone +39 348 7998657
email: e.scala@idi.it
1 | Abstract
Introduction | Shellfish allergy is an important cause
of food allergies worldwide. Both in vivo and in vitrodiagnostics failure nowadays is caused by the poor quality of the
extracts associated with the scarce availability of allergenic molecules
in the market. It is known that not all patients with shellfish
allergies experience adverse reactions to mollusks. It is still unclear
how to detect and diagnose correctly these patients.
Aim | To investigate the features of shrimp-allergic
patients either reactive or tolerant to mollusks, with the currently
available diagnostic methods.
Methods| Nineteen centers, scattered throughout Italy,
participated in the study, enrolling patients allergic to shrimp with or
without associated reactions to mollusks. Patients underwent skin tests
using commercial extracts or fresh raw and cooked foods, and IgE
reactivity to currently available allergenic extracts and molecules was
measured in vitro .
Results| Two hundred and forty-seven individuals with
a history of adverse reaction to crustaceans participated in the study.
Only 47.8% of them reacted after cephalopod or bivalve ingestion. None
of the tests used, either in vivo or in vitro , was able to
detect all selected patients. Accordingly, a great heterogeneity of
results was observed with an agreement between in vivo andin vitro tests ranging between 52% and 62% of cases. Skin tests
were able to identify the cephalopod and bivalve reactors (p
<0.001), also using fresh cooked or raw food (p
<0.001). The reactivity profile of mollusk reactors was
dominated by Pen m 1, over Pen m 2 and Pen m 4 compared to the tolerant
subjects, but 33% of patients allergic to shellfish were not detected
by any of the available molecules. A higher frequency of shrimp
hypersensitivity was recorded in northern Italy, while mollusk
reactivity was more frequent in the center-south.
Conclusion | The current diagnostic methods are
inadequate to predict the cross-reactivity between crustaceans and
mollusks. The detection of mollusks hypersensitivity must still rely on
skin tests with fresh material. There is no need to exclude mollusks
from shrimp allergic patients’ diet unless clinical history, the
available diagnostic instruments, and/or tolerance tests support such a
decision. Primary sensitization to mollusks seems possible.