3 | PATIENTS AND METHODS
Nineteen Italian allergy centers took part in a multicenter cross-sectional observational clinical survey on crustacean allergy. In every participating center, doctors consecutively enrolled the largest possible number of patients with unequivocal crustacean (shrimp) and/or mollusks (Bivalvia and/ or Cephalopoda ) allergy, between May 15th and November 15th, 2021. The patients with a history of food allergy to shellfish confirmed by a positive skin prick test (SPT) with commercial shrimp extract and/or with prick-prick test (PPT) with fresh raw or cooked food were carefully interviewed about seafood, crustaceans and/or mollusks tolerance. Diagnosis of tolerance was based on patient’s clinical history (i.e., consumption of the culprit food without problems).
Shellfish-induced allergic reactions reported by patients included both mild (such as oral allergy syndrome or isolated gastrointestinal reactions) and moderate-severe reactions (i.e., urticaria/angioedema, anaphylaxis). Given the observational nature of the study, no randomization procedure was be implemented during enrollment. The clinical histories were confirmed by a positive skin prick test (SPT) with fresh food (either raw or cooked) and/or commercial extracts of shrimp and mollusks currently available in Italy (Alk-Abello’ s.p.a., Allergy Therapeutics Italia, Anallergo, Firma Srl, Roxall Italia, Lofarma, and Stallergenes Italia Srl) and/or by the detection of IgE specific for seafood extracts by ImmunoCAP (shrimp, mussel, clam, octopus or squid), and Pen a 1 (tropomyosin) (Thermo Fisher, Uppsala, Sweden). In a subset (98 individuals) a more in-depth evaluation was carried out by the Allergy Explorer-ALEX2® (Macroarray Diagnostics, Vienna) multiplex platform evaluating a broader profile of seafood molecules (9), including Pen m 1 (tropomyosin), Pen m 2 (arginine kinase), Pen m 3 (myosin light chain), and Pen m 4 (sarcoplasmic calcium binding protein) all from Black-Tiger shrimp (Penaeus monodon ), Cra c 6 (the troponin-c from brown shrimp, Crangon crangon ), Der p 10 (tropomyosin), and Der p 11 (paramyosin) both fromDermatophagoides pteronyssinus , as well as of seafood extracts, including crab, lobster, northern shrimp, white shrimp, squid, mussel, oyster, clam, and scallop. IgE levels >0.3kUA/L were considered positive as for manufacturer’s instructions.
The diagnosis of seafood allergy was not confirmed by blinded or open oral food challenges due both to the severity of several reactions and the fact that many centers were not sufficiently equipped in terms of facilities or personnel to manage possible severe allergic reactions.