title: IgE reactivity against a cross-reactive allergen in crustacea and mollusca: evidence for tropomyosin as the common allergen.
abstract: BACKGROUND
  Although cross-reactivity between mollusks and other crustaceans in shrimp-sensitive subjects has been reported, the mechanism of this allergenic cross-reactivity has not been studied in detail.
  
  
  OBJECTIVE
  To investigate this cross-reactivity in vitro, we have taken advantage of a complementary DNA that expresses tropomyosin, the immunodominant shrimp allergen.
  
  
  METHODS
  Serum IgE from nine patients with known anaphylaxis to shrimp and five normal volunteers were analyzed by immunoblotting against 13 distinct crustaceans and mollusks. As additional antigens, muscle preparations were isolated from grasshopper, cockroach, fruit fly, chicken, and mouse.
  
  
  RESULTS
  Sera from all patients, but not control subjects, reacted specifically with a 38 kd protein in all crustaceans and mollusks studied. In addition, 8 of 9 sera from patients, but from none of the normal control subjects, recognized proteins of various other molecular weights among the mollusk extracts studied. The 38 kd protein was identified as tropomyosin and was shown to share immunodominant epitopes among all species of crustaceans and mollusks tested by specific absorption studies. Moreover, sera from all nine subjects with shrimp allergy demonstrated IgE reactivities against grasshopper, cockroach, and fruit fly but not chicken or murine muscle.
  
  
  CONCLUSIONS
  The allergic epitopes on tropomyosin are conserved among invertebrates including not only shellfish but also insects. This latter observation suggests that persons sensitive to shrimp should undergo further study for potential cross-reactive inhalant or ingested insect sensitivity.
authors.affiliation: Division of Rheumatology/Allergy and Clinical Immunology, School of Medicine, University of California, Davis 95616, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Leung
authors.forename: W K
authors.initials: WK
authors.lastname: Chow
authors.forename: S
authors.initials: S
authors.lastname: Duffey
authors.forename: H S
authors.initials: HS
authors.lastname: Kwan
authors.forename: M E
authors.initials: ME
authors.lastname: Gershwin
authors.forename: K H
authors.initials: KH
authors.lastname: Chu
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D002645:Chickens / Q000276:immunology; D003429:Cross Reactions; D003445:Crustacea / Q000276:immunology*; D018076:DNA, Complementary / Q000235:genetics / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology; D007073:Immunoglobulin E / Q000276:immunology*; D007313:Insecta / Q000276:immunology; D051379:Mice; D008970:Molecular Weight; D008974:Mollusca / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D014335:Tropomyosin / Q000276:immunology*; D014714:Vertebrates / Q000276:immunology
chemical_list: D000485:Allergens; D018076:DNA, Complementary; D016056:Immunodominant Epitopes; D011994:Recombinant Proteins; D014335:Tropomyosin; D007073:Immunoglobulin E