Occupational Allergic Sensitization Among Workers Processing King Crab (Paralithodes camtschaticus) and Edible Crab (Cancer pagurus) in Norway and Identification of Novel Putative Allergenic Proteins

Abstract

Introduction: Asthma and allergy occur frequently among seafood processing workers, with the highest prevalence seen in the crustacean processing industry. In this study we established for the first time the prevalence of allergic sensitization in the Norwegian king- and edible crab processing industry and characterized the IgE-reactive proteins.Materials and Methods: Two populations of crab processing workers participated; 119 king crab and 65 edible crab workers. The investigation included information on work tasks and health through a detailed questionnaire. Allergic sensitization was investigated by crab-specific IgE quantification and skin prick tests (SPT) to four in-house prepared crab extracts; raw meat, cooked meat, raw intestines and raw shell. Allergen-specific IgE binding patterns were analyzed by IgE immunoblotting to the four allergen extracts using worker serum samples. Total proteins in crab SPT extracts and immunoblot-based IgE binding proteins were identified by mass spectrometric analysis.Results: Positive SPTs were established in 17.5% of king- and 18.1% of edible crab workers, while elevated IgE to crab were demonstrated in 8.9% of king- and 12.2% of edible crab processing workers. There was no significant difference between the king and edible crab workers with respect to self-reported respiratory symptoms, elevated specific IgE to crab or SPT results. Individual workers exhibited differential IgE binding patterns to different crab extracts, with most frequent binding to tropomyosin and arginine kinase and two novel IgE binding proteins, hemocyanin and enolase, identified as king- and edible crab allergens.Conclusions: Occupational exposure to king- and edible crabs may frequently cause IgE mediated allergic sensitization. Future investigations addressing the diagnostic value of crab allergens including tropomyosin and arginine kinase and the less well-known IgE-binding proteins hemocyanin and enolase in a component-resolved diagnostic approach to crab allergy should be encouraged.

EAACIMolecular Allergology User's Guide 2.0

“…IgE sensitization to shrimp hemocyanin has been reported to be 29% in DBPCFC‐confirmed shrimp allergic patients 15 and 40% in a Spanish population 1070 . In a recent study, strong IgE sensitization to crab hemocyanin was observed in crab‐processing workers by inhalational exposure to aerosolized matter 1071 . Therefore, hemocyanin‐specific IgE may be a potential diagnostic marker for occupational exposure and symptoms to shellfish allergens.…”

“…1070 In a recent study, strong IgE sensitization to crab hemocyanin was observed in crab-processing workers by inhalational exposure to aerosolized matter. 1071 Therefore, hemocyaninspecific IgE may be a potential diagnostic marker for occupational exposure and symptoms to shellfish allergens.…”

IgE-Mediated Shellfish Allergy in Children

“…The clinical relevance of these allergens is still unclear. However, hemocyanin seems to have an important role in cross-reactivity with mites, cockroaches, and other invertebrates such as snails [ 64 ] [ 73 , 74 ].…”

Occupational inhalant allergy in food handling occupations

“…In the former group, atopy was significantly associated with positive Skin prick test (SPT) or raised IgE to king- and edible crab. Workers exhibited differential IgE binding patterns to various forms of crab extracts (raw and cooked meat, intestines, shell) frequently to tropomyosin and arginine kinase as well as to two novel proteins, hemocyanin and enolase [31 ▪ ]. More studies are needed to determine their relevance for occupational sensitization through inhalation.…”