title: Characterization of Der p 21, a new important allergen derived from the gut of house dust mites.
abstract: BACKGROUND
  The house dust mite (HDM) Dermatophagoides pteronyssinus is a major allergen source eliciting allergic asthma. The aim of the study was to identify new important HDM allergens associated with allergic asthma.
  
  
  METHODS
  A cDNA coding for a new mite allergen, designated Der p 21, was isolated using immunoglobulin E (IgE) antibodies from patients with allergic asthma out of a D. pteronyssinus expression cDNA library and expressed in Escherichia coli.
  
  
  RESULTS
  Circular dichroism analysis of the purified allergen showed that rDer p 21 (14 726 Da) is one of the few mite allergens with an alpha-helical secondary structure. The protein exhibited high thermal stability and refolding capacity, and, as determined by small angle X-ray scattering, formed a dimer consisting of two flat triangles. rDer p 21 bound high levels of patients' IgE antibodies and showed high allergenic activity in basophil activation experiments. Rabbit anti-Der p 21 IgG antibodies inhibited mite-allergic patients' IgE binding and allowed the ultrastructural localization of the allergen in the midgut (epithelium, lumen and faeces) of D. pteronyssinus by immunogold electron microscopy. Der p 21 revealed sequence homology with group 5 mite allergens, but IgE and IgG reactivity data and cross-inhibition studies identified it as a new mite allergen.
  
  
  CONCLUSIONS
  Der p 21 is a new important mite allergen which is liberated into the environment via faecal particles and hence may be associated with allergic asthma.
authors.affiliation: Division of Immunopathology, Department of Pathophysiology, Center for Physiology and Pathophysiology, Medical University of Vienna, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Weghofer
authors.forename: Y
authors.initials: Y
authors.lastname: Dall'Antonia
authors.forename: M
authors.initials: M
authors.lastname: Grote
authors.forename: A
authors.initials: A
authors.lastname: Stöcklinger
authors.forename: M
authors.initials: M
authors.lastname: Kneidinger
authors.forename: N
authors.initials: N
authors.lastname: Balic
authors.forename: M-T
authors.initials: MT
authors.lastname: Krauth
authors.forename: E
authors.initials: E
authors.lastname: Fernández-Caldas
authors.forename: W R
authors.initials: WR
authors.lastname: Thomas
authors.forename: M
authors.initials: M
authors.lastname: van Hage
authors.forename: S
authors.initials: S
authors.lastname: Vieths
authors.forename: S
authors.initials: S
authors.lastname: Spitzauer
authors.forename: F
authors.initials: F
authors.lastname: Horak
authors.forename: D I
authors.initials: DI
authors.lastname: Svergun
authors.forename: P V
authors.initials: PV
authors.lastname: Konarev
authors.forename: P
authors.initials: P
authors.lastname: Valent
authors.forename: J
authors.initials: J
authors.lastname: Thalhamer
authors.forename: W
authors.initials: W
authors.lastname: Keller
authors.forename: R
authors.initials: R
authors.lastname: Valenta
authors.forename: S
authors.initials: S
authors.lastname: Vrtala
mesh_terms: D000485:Allergens / Q000737:chemistry* / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D000595:Amino Acid Sequence; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000737:chemistry* / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D001249:Asthma / Q000276:immunology*; D001483:Base Sequence; D001491:Basophils / Q000276:immunology; D002942:Circular Dichroism; D018076:DNA, Complementary; D040002:Dermatophagoides pteronyssinus / Q000276:immunology* / Q000648:ultrastructure; D004391:Dust / Q000276:immunology; D004847:Epithelial Cells / Q000276:immunology / Q000648:ultrastructure; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology; D007422:Intestines / Q000276:immunology / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D018076:DNA, Complementary; D004391:Dust; D007073:Immunoglobulin E