title: A double-blind, placebo-controlled oral challenge study with lyophilized larvae and antigen of the fish parasite, Anisakis simplex.
abstract: BACKGROUND
  The third-stage larvae of Anisakis simplex may be a hidden source of allergens in fish. The objective was to determine whether the ingestion of lyophilized A. simplex larvae, or antigen, induces clinical symptoms in a group of A. simplex-sensitized patients.
  
  
  METHODS
  Double-blind, placebo-controlled oral challenges were conducted in 11 individuals who had experienced allergic reactions after eating fish. Another patient had chronic urticaria unrelated to the ingestion of fish. All patients had positive skin tests and specific IgE determinations for A. simplex and negative skin tests to a battery of fish species. Conjunctival tests with A. simplex extracts were conducted in all patients and in five controls. The 12 patients received capsules containing either lactose or one, five, or 25 lyophilized larvae of A. simplex at 2-h intervals in a double-blind fashion. The highest single dose was 100 larvae. ECP and tryptase levels in serum were measured before and after the last oral challenge. Lyophilized antigen was also given to five patients.
  
  
  RESULTS
  None of the 12 patients experienced a positive reaction after the ingestion of the placebo, the lyophilized larvae, or the antigen. Tryptase and ECP levels before and after challenges did not change significantly. Conjunctival provocation tests were positive in 11 out of the 12 patients and in none of the controls.
  
  
  CONCLUSIONS
  The ingestion of 100 lyophilized A. simplex larvae, or its equivalent in antigen, does not induce clinical symptoms in individuals with a clinical history and laboratory findings of hypersensitivity to A. simplex. The data suggest that only the ingestion of live larvae may be capable of inducing allergic manifestations.
authors.affiliation: Servicio de Alergia, Fundación Jiménez Díaz, Universidad Autónoma de Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Sastre
authors.forename: M
authors.initials: M
authors.lastname: Lluch-Bernal
authors.forename: S
authors.initials: S
authors.lastname: Quirce
authors.forename: I
authors.initials: I
authors.lastname: Arrieta
authors.forename: C
authors.initials: C
authors.lastname: Lahoz
authors.forename: A
authors.initials: A
authors.lastname: Del Amo
authors.forename: E
authors.initials: E
authors.lastname: Fernández-Caldas
authors.forename: F
authors.initials: F
authors.lastname: Marañón
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000485:Allergens / Q000276:immunology; D000818:Animals; D017163:Anisakis / Q000276:immunology*; D000947:Antigens, Helminth / Q000276:immunology; D001798:Blood Proteins / Q000032:analysis; D053818:Chymases; D003228:Conjunctiva / Q000276:immunology; D004311:Double-Blind Method; D047091:Eosinophil Granule Proteins; D005260:Female; D005399:Fishes / Q000469:parasitology; D005512:Food Hypersensitivity / Q000097:blood / Q000276:immunology*; D005612:Freeze Drying; D006801:Humans; D007073:Immunoglobulin E / Q000032:analysis; D007814:Larva / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010919:Placebos; D012260:Ribonucleases; D012697:Serine Endopeptidases / Q000097:blood; D012882:Skin Tests; D053802:Tryptases
chemical_list: D000485:Allergens; D000947:Antigens, Helminth; D001798:Blood Proteins; D047091:Eosinophil Granule Proteins; D010919:Placebos; D007073:Immunoglobulin E; D012260:Ribonucleases; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; D053802:Tryptases