2 | INTRODUCTION
Seafood is included among the “Big Eight” food groups responsible for
most cases of food allergy. It is estimated that depending on the
different geographic areas, about 3% of the general population is
allergic to shellfish (1,2). This generic term includes more than 300
different invertebrate species which are divided into two large groups:
crustaceans (shrimps, crabs, lobsters etc.) and mollusks
(Bivalvia , such as clam, mussels, scallops or oysters, andCephalopoda , like squids, cuttlefish or octopuses etc.)(3)(4).
These taxonomic classifications are essential to predict the structural,
immunological and allergological similarities that underlie a possible
cross-reactivity. The availability and consumption of seafood vary
greatly in different parts of the world, representing the second cause
of primary food allergy in Italy, after Lipid transfer proteins (5).
Even eating habits, including the different methods of food processing,
may exert a strong impact on the incidence and severity of allergy to
crustaceans and seafood, since in some cases physical treatments can
increase or reduce IgE reactivity(6), depending on the molecule involved
in patient sensitization (7). So far, it has been argued that due to the
cross-reactivity among allergens in invertebrates, primarily
tropomyosin, the patient allergic to crustaceans should also exclude
cephalopods and Bivalvia from the diet. However, recent studies seem to
suggest that this is not the case; in fact, a significant proportion of
crustacean allergic patients report that they usually tolerate other
invertebrates (8). One of the main diagnostic problems is that all the
molecules commercially available for in vitro tests come from
crustaceans and not from mollusks. As a consequence, IgE diagnostic
approach for mollusks adverse reaction is always indirectly based on a
presumptive but not fully demonstrated cross-reactivity, unless tests
with fresh, raw or cooked cephalopod or Bivalvia are carried out, with
all the drawbacks associated with such approach.
The main aims of this study were (i) to investigate the prevalence of
patients allergic to crustaceans with or without cross-reactivity to
cephalopods and/or bivalve mollusks; (ii) to define the molecular
profile in both cross-reacting and non-cross-reacting individuals; (iii)
to highlight any differences in the severity of the allergic reactions,
and (iv) to investigate the geographical differences in seafood
sensitization profiles in Italy.