Immunologic characterization and allergenicity of recombinant Tyr p 3 allergen from the storage mite Tyrophagus putrescentiae.
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.
Liao
En-Chih
EC
Department of Tropical Medicine and Institute of Clinical Medicine, National Yang Ming University, Taipei, Taiwan, ROC.
Hsu
Err-Lieh
EL
Tsai
Jaw-Ji
JJ
Ho
Chau-Mei
CM