title: Immunologic characterization and allergenicity of recombinant Tyr p 3 allergen from the storage mite Tyrophagus putrescentiae.
abstract: BACKGROUND
  The involvement of the storage mite Tyrophagus putrescentiae in allergies has been increasingly reported in many countries. Molecular analysis has shown that group 3 mite allergens are homologous to trypsin. Similar allergens have not been identified in T. putrescentiae. Our aims were to characterize group 3 allergens in T. putrescentiae and to investigate their significance in allergenicity.
  
  
  METHODS
  cDNAs of PreTyr p 3 and rTyr p 3 from T. putrescentiae were cloned and expressed in Escherichia coli. Native Tyr p 3 (nTyr p 3) was purified from spent growth medium with an affinity column coupling of antibody. Biological activities of rTyr p 3 were compared with nTyr p 3 in terms of IgE activity, enzymatic activity and histamine release.
  
  
  RESULTS
  Full-length cDNA of PreTyr p 3 encodes a 285-amino acid trypsin-like protease and acquires enzymatic activity after removing the pre- and pro-sequences. rTyr p 3 is a 26-kDa protein with equivalent IgE reactivity but weaker enzymatic activity than that of nTyr p 3. A limited level of cross-reactivity has been found between rTyr p 3, Der p 3 and Blomia. Eight of 10 T. putrescentiae-sensitized individuals showed >50% histamine release after triggering with rTyr p 3.
  
  
  CONCLUSIONS
  Our studies demonstrate that Tyr p 3 is a frequent allergen (58%) in T. putrescentiae-sensitized patients. Since rTyr p 3 displays equivalent biological activities as nTyr p 3, the role of group 3 allergens can be studied using rTyr p 3 to elucidate the pathogenic effects and diagnostic applications of Tyr p 3.
authors.affiliation: Department of Tropical Medicine and Institute of Clinical Medicine, National Yang Ming University, Taipei, Taiwan, ROC.
authors.forename: En-Chih
authors.initials: EC
authors.lastname: Liao
authors.forename: Err-Lieh
authors.initials: EL
authors.lastname: Hsu
authors.forename: Jaw-Ji
authors.initials: JJ
authors.lastname: Tsai
authors.forename: Chau-Mei
authors.initials: CM
authors.lastname: Ho