Characterization of Der p 21, a new important allergen derived from the gut of house dust mites

Allergy. 2008 Jun;63(6):758-67. doi: 10.1111/j.1398-9995.2008.01647.x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allergens / chemistry*
  • Allergens / genetics
  • Allergens / immunology*
  • Allergens / isolation & purification
  • Amino Acid Sequence
  • Animals
  • Antigens, Dermatophagoides / chemistry*
  • Antigens, Dermatophagoides / genetics
  • Antigens, Dermatophagoides / immunology*
  • Antigens, Dermatophagoides / isolation & purification
  • Asthma / immunology*
  • Base Sequence
  • Basophils / immunology
  • Circular Dichroism
  • DNA, Complementary
  • Dermatophagoides pteronyssinus / immunology*
  • Dermatophagoides pteronyssinus / ultrastructure
  • Dust / immunology
  • Epithelial Cells / immunology
  • Epithelial Cells / ultrastructure
  • Humans
  • Immunoglobulin E / immunology
  • Intestines / immunology
  • Intestines / ultrastructure
  • Microscopy, Immunoelectron
  • Molecular Sequence Data


  • Allergens
  • Antigens, Dermatophagoides
  • DNA, Complementary
  • Dust
  • Immunoglobulin E

Associated data

  • GENBANK/DQ354124