Ask The Expert
February 25, 2021
Relationship of Dust Mites and Crustaceans
While it has been reported that up to 15% of patients highly sensitized to dust mites are also sensitized to crustaceans, e.g. shrimp and snails, due largely to the cross-reacting anti-tropomyosin IgE, is there risk of inducing clinically significant allergic reactions to the crustaceans while treating patients with dust mite immunotherapy? Should patients highly allergic to dust mites be advised to avoid eating crustaceans?
Shellfish allergy is an important cause of anaphylaxis in America and Asia. The principal allergen is tropomyosin, a shellfish structural protein, which is a food panallergen founded in the majority of shellfish. This allergen can also be found in dust mites.(1)
Tropomyosin is a skeletal muscle protein; it is a panallergen in invertebrates and the major allergen in all edible shellfish. Shrimp, lobster, and crab tropomyosins share between 91 and 100% sequence homology, which explains the significant degree of IgE cross-reactivity between various species of shellfish. Tropomyosins from house dust mites (HDMs) and cockroaches also share high sequence homology with tropomyosin from shellfish.(2)
Inhalation exposure to HDM tropomyosins has been hypothesized to be a major risk factor for shellfish allergy due to the subsequent IgE cross-reactivity to shellfish tropomyosins, accounting for the late age of onset and the prevalence of oral symptoms observed in Asia-Pacific region where HDMs are quite common. This data is also supported by the high correlation between HDM sensitization and allergy, and sensitization to shellfish in atopic populations.(3)
Research suggests that allergen-specific immunotherapy using HDM extracts does not induce clinically relevant sensitization to tropomyosin. Van Ree et al. studied sera from patients allergic to HDM who received specific allergen immunotherapy. Serum samples were taken at the start of immunotherapy and 14 to 20 months later. At the beginning of immunotherapy, shrimp-specific IgE was positive in 3/17 subjects. After immunotherapy, IgE reactivity to Der p 1 and Der p 2 did not increase. The three patients with initial positive specific IgE to shrimp were the only patients who exhibited clinical symptoms after eating shrimp. Therefore, it appears that HDM immunotherapy does not increase the risk of reaction after ingestion of shrimp in previously non-sensitized patients. In a study with individuals allergic to HDMs not sensitized to tropomyosin, it was observed that injection of subcutaneous immunotherapy with HDM extracts did not appear to induce de novo sensitization to tropomyosin after three years of treatment. In fact, Cortellini et al. published a case report of a 15-year-old male diagnosed with both shrimp and HDM allergy, who tolerated ingestion of shrimp after 12 months of sublingual immunotherapy with HDM. In conclusion, these findings open the possibility of new therapeutic approaches with allergen immunotherapy for shellfish allergy.(4)
1. Wong L, Huang CH, Lee BW. Shellfish and House Dust Mite Allergies: Is the Link Tropomyosin? Allergy Asthma Immunol Res. marzo de 2016;8(2):101-6.
2. Klaewsongkram J. High prevalence of shellfish and house dust mite allergies in Asia-Pacific: probably not just a coincidence. Asian Pac J Allergy Immunol. diciembre de 2012;30(4):247-8.
3. Wong L, Tham EH, Lee BW. An update on shellfish allergy. Curr Opin Allergy Clin Immunol. junio de 2019;19(3):236-42.
4. El-Qutob D. Shrimp allergy: beyond avoidance diet. Eur Ann Allergy Clin Immunol. noviembre de 2017;49(6):252-6.
Marie Angelique Lazo-Betetta, MD
Centro de Enfermedades Alérgicas “Dr. Luis E. Betetta” S.A.
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