4.3 | Sensitization profiles and clinical correlations
One hundred-eighteen (47,8%) patients enrolled because allergic to
crustaceans, reported also moderate (80.5%) to severe (19.5%)
reactions after ingestion of mollusks.
There was no difference in the frequency of reactive episodes related to
sex or age.
Interestingly, a higher risk of developing a severe reaction after
mollusks intake was associated with skin test reactivity to commercial
extracts of cephalopod (OR: 4.81; CI 1.8-9.3; p <0.001) or
bivalve (OR: 14.970; CI 4.2-53.3; p <0.001). Similarly,
mollusk reactors showed a high frequency of reactivity to both raw (OR:
4.492; CI 1.9-10.4; p <0.001) and cooked squid (OR: 3.040; CI
1.3-7.3; p <0.001), and to both raw (OR: 20.907; CI 5.8-75.2;
p <0.001) and cooked clam (OR: 17.249; CI 3.1-41.1; p
<0.001).
The multiple logistic regression analysis, when simultaneously adjusted
for the presence of specific IgE to all the extracts studied, age, and
sex, showed a significant relationship between a history of adverse
reaction to mollusks and IgE reactivity to both cephalopods
(ORadj 4.0, 95% CI 1.5-10.7, p <0,01) or
bivalve (ORadj 7.6, 95% CI 3.1-18.6, p
<0.0001) extracts. Moreover, as shown in Table 3, allergy to
mollusks was associated with IgE reactivity to northern shrimp
(Litopaenaeus setiferus ), squid (Loligo spp.), mussel
(Mytilus edulis ), oyster (Ostrea edulis ), clam
(Ruditapes spp.), and scallop (Pecten spp.) extracts. Pen
m 1 (Penaeus monodon tropomyosin) hypersensitivity was
significantly associated with an increased risk of severe reaction to
mollusks.
Three patients scoring SPT positive to crustaceans showed in
vitro sensitization to bivalves (both oyster and mussel) in two cases
and squid in one case, with no sign of IgE reactivity against any the
extracts and molecules of crustaceans in vitro , with only a low
reactivity in one case to paramyosin (0.24 kU/L) and tropomyosin (0.39
kU/L) from house dust mite (Der p 11 and Der p 10 respectively).
As summarized in Figure 1, the molecular sensitization profile was
dominated by Pen m 1, but more frequently in those who did not tolerate
mollusks. Moreover, mollusks reactors had also two times higher
frequency of sensitization to arginine kinase and sarcoplasmic
Ca++ binding protein (Figure 1). Interestingly, the
number of crustacean allergic patients who did not react to any of the
molecules currently available for in vitro diagnostics was very
high, particularly among those who tolerated cephalopods and bivalves
(43%).
4.4 |Geographical differences
in seafood sensitization profiles
When we analyzed the data as a function of the geographical distribution
of patients, we found a significantly higher frequency of sensitization
to crustaceans in northern Italy, irrespective of the diagnostic tests
used (skin prick test, prick-prick test with fresh or cooked food, and
specific IgE measurement for allergen extracts), whilst in
centre-southern Italy, a more frequent sensitization to Bivalvia was
recorded (Figure 2 A-C). This observation was in keeping with a higher
frequency of reactions to bivalve in the south, whilst the sensitization
levels to cephalopod were comparable among south and north (Figure 2 D).