title: The effect of storage on allergen and microbial agent levels in frozen house dust.
abstract: BACKGROUND
  House dust samples collected for exposure studies are often stored for variable time periods until analysis. However, there is currently no information on the effects of dust storage on the content of biocontaminants. Therefore, associations were analysed between the levels of mite allergens (Der p 1, Der f 1), cat allergen (Fel d 1) and microbial components (endotoxin, beta(1-->3)-glucan) on the one hand and the storage duration of dust samples at -20 degrees C on the other hand.
  
  
  METHODS
  Within the framework of a study on the influences of INdoor factors and Genetics on Asthma (INGA), dust samples were collected from living room floors between June 1995 and August 1998 and extracted according to a standardized protocol. The concentrations of Der p 1, Der f 1, Fel d 1 and beta(1-->3)-glucan were determined with specific enzyme immunoassays. Endotoxin content was quantified using a chromogenic kinetic Limulus amoebocyte lysate (LAL) test. All concentrations were expressed per gram of dust
  
  
  RESULTS
  Dust samples (n = 1236) were obtained from 655 homes in Hamburg, Hettstedt, Zerbst and Bitterfeld. Storage duration (range 8-298 days) was grouped into four categories (<or= 60 d; 61-90 d; 91-120 d; > 120 d). After adjustment for city of residence and season of dust sampling, means ratios comparing categories 2-4 to the first category were not statistically significant for Der p 1, Der f 1, endotoxin and beta(1-->3 glucan). However, Fel d 1 concentrations significantly declined with increased storage times of dust samples.
  
  
  CONCLUSIONS
  Storage of house dust at -20 degrees C for up to 10 months has no effect on mite allergen, endotoxin and beta(1-->3)-glucan levels. A potential loss of Fel d 1 during storage of frozen dust samples needs further investigations by repeated measurements of allergen in identical dust samples.
authors.affiliation: Friedrich-Schiller-University of Jena, Institute of Immunology, Jena, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Fahlbusch
authors.forename: A
authors.initials: A
authors.lastname: Koch
authors.forename: J
authors.initials: J
authors.lastname: Douwes
authors.forename: W
authors.initials: W
authors.lastname: Bischof
authors.forename: U
authors.initials: U
authors.lastname: Gehring
authors.forename: K
authors.initials: K
authors.lastname: Richter
authors.forename: H-E
authors.initials: HE
authors.lastname: Wichmann
authors.forename: J
authors.initials: J
authors.lastname: Heinrich
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis; D000485:Allergens / Q000032:analysis* / Q000276:immunology*; D000704:Analysis of Variance; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000032:analysis / Q000276:immunology; D060829:Arthropod Proteins; D001249:Asthma / Q000276:immunology; D003546:Cysteine Endopeptidases; D004306:Dose-Response Relationship, Immunologic; D004731:Endotoxins / Q000032:analysis / Q000276:immunology; D005858:Germany; D005936:Glucans / Q000032:analysis / Q000276:immunology; D006023:Glycoproteins / Q000032:analysis / Q000276:immunology; D006801:Humans; D039981:Pyroglyphidae / Q000276:immunology*; D013223:Statistics as Topic; D013997:Time Factors; D047071:beta-Glucans
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D004731:Endotoxins; D005936:Glucans; D006023:Glycoproteins; D047071:beta-Glucans; C033363:beta-1,3-glucan; D003546:Cysteine Endopeptidases; C451159:Dermatophagoides farinae antigen f 1; C451162:Dermatophagoides pteronyssinus antigen p 1; C059296:Fel d 1 protein, Felis domesticus