title: [Protease inhibitory activities of nasal secretion on house dust mite allergen].
abstract: OBJECTIVE
  To elucidate the interaction of protease inhibitors and house dust mite allergen in vitro.
  
  
  METHODS
  Nasal secretion was collected by suction from patients with house dust mite nasal allergy, diluted immediately with PBS pH 7.0, mixed with vortex for 10 minutes, and then centrifuged at 2,000 g for 10 minutes. The supernatant was kept at -80 degrees C for use. Synthetic low molecular weight fluorogenic peptide substrates were applied to evaluate protease activities. Crude mite extract and other proteases were used, each of them was preincubated in the presence or absence of nasal fluid or other protease inhibitors at 37 degrees C for 30 minutes. The intensity of fluorescence of aminomethylcoumarin released from the cleaved substrate was measured.
  
  
  RESULTS
  Nasal fluid exhibited mild trypsin-like and other protease activities. It inhibited the activities of trypsin and trypsin-like serine proteases and papain-like cysteine proteases in crude mite extract in a dose-dependent manner.
  
  
  CONCLUSIONS
  Nasal fluid possibly plays a role in inhibiting penetration of allergen into the nasal mucosa by producing protease inhibitor-protease complex in the nasal mucus layer of patients with mite allergy.
authors.affiliation: First Clinical College, Beijing Medical University, Beijing 100034.
authors.forename: S
authors.initials: S
authors.lastname: Xiao
authors.forename: Q
authors.initials: Q
authors.lastname: Wang
authors.forename: Z
authors.initials: Z
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens; D000818:Animals; D012634:Bodily Secretions / Q000737:chemistry; D002648:Child; D003546:Cysteine Endopeptidases / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008924:Mite Infestations; D008925:Mites / Q000737:chemistry / Q000276:immunology*; D011480:Protease Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D012221:Rhinitis, Allergic, Perennial / Q000201:enzymology; D012697:Serine Endopeptidases / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism*
chemical_list: D000485:Allergens; D011480:Protease Inhibitors; D012697:Serine Endopeptidases; D014357:Trypsin; D003546:Cysteine Endopeptidases