title: Depigmented and polymerised house dust mite allergoid: allergen content, induction of IgG4 and clinical response.
abstract: BACKGROUND
  Polymerised allergenic extracts (allergoids) are commonly used in allergen immunotherapy. Clinical efficacy and safety of these extracts have been demonstrated. Recently, allergen sequences have been identified by mass spectrometry in depigmented and polymerised (Dpg-Pol) extracts. The objectives of this study were to investigate the presence of allergens in Dpg-Pol extracts of house dust mite and to analyze the immunological changes induced by these extracts in asthmatic patients enrolled in a double-blind, placebo-controlled study.
  
  
  METHODS
  Dpg-Pol extracts were manufactured and vaccines with a composition of 50% Dermatophagoides pteronyssinus and 50% D. farinae (100 HEPL/ml) were prepared. Allergen composition was analyzed by mass spectrometry. Patients with asthma and rhinoconjunctivitis were treated in a 1-year, double-blind, placebo-controlled, parallel-group study with 6 up-dosing and monthly maintenance injections. Specific IgE and IgG4 titres to D. pteronyssinus, Der p 1 and Der p 2 were measured in patients' sera using the CAP system and direct ELISA experiments.
  
  
  RESULTS
  Sequences from the major allergens Der p 1 and Der p 2 and from other allergens were identified in native and Dpg-Pol extracts. There was a statistically significant increase in specific IgG4, a decrease in the ratio of IgE/IgG4 to D. pteronyssinus and a significant increase in specific IgG4 to Der p 1 and Der p 2 in the patients allotted to active treatment.
  
  
  CONCLUSIONS
  The detection of allergen sequences suggests preservation of major and minor allergens in Dpg-Pol allergoids from house dust mites. Efficacy in asthma treatment and the increase in specific IgG4 seem to be associated with the presence of major allergens in Dpg-Pol allergen extracts.
authors.affiliation: Research and Development Department, Laboratorios LETI, S.L., Calle del Sol No. 5, Tres Cantos, Madrid, Spain.
authors.forename: M T
authors.initials: MT
authors.lastname: Gallego
authors.forename: V
authors.initials: V
authors.lastname: Iraola
authors.forename: M
authors.initials: M
authors.lastname: Himly
authors.forename: D S
authors.initials: DS
authors.lastname: Robinson
authors.forename: C
authors.initials: C
authors.lastname: Badiola
authors.forename: J C
authors.initials: JC
authors.lastname: García-Robaina
authors.forename: P
authors.initials: P
authors.lastname: Briza
authors.forename: J
authors.initials: J
authors.lastname: Carnés
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000737:chemistry / Q000276:immunology*; D000080384:Allergoids; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000737:chemistry / Q000276:immunology; D060829:Arthropod Proteins; D001249:Asthma / Q000209:etiology / Q000276:immunology / Q000503:physiopathology / Q000628:therapy*; D003233:Conjunctivitis, Allergic / Q000276:immunology / Q000628:therapy; D003546:Cysteine Endopeptidases; D040001:Dermatophagoides farinae / Q000276:immunology; D040002:Dermatophagoides pteronyssinus / Q000276:immunology; D003888:Desensitization, Immunologic / Q000379:methods*; D004311:Double-Blind Method; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood*; D010936:Plant Extracts / Q000737:chemistry / Q000276:immunology*; D039981:Pyroglyphidae / Q000276:immunology*; D012221:Rhinitis, Allergic, Perennial / Q000276:immunology / Q000628:therapy; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000485:Allergens; D000080384:Allergoids; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C451163:Dermatophagoides pteronyssinus antigen p 2; D007074:Immunoglobulin G; D010936:Plant Extracts; D007073:Immunoglobulin E; D003546:Cysteine Endopeptidases; C451162:Dermatophagoides pteronyssinus antigen p 1