title: Differential effect of mattress covers on the level of Der p 1 and Der f 1 in dust.
abstract: BACKGROUND
  Exposure to house dust mite (HDM) allergens can lead to the development of allergic complaints. Mattress covers seem to be an obvious option for lowering allergen exposure in sensitized individuals. Previous studies have shown that Dermatophagoides pteronissinus was the most prevalent HDM species in the Netherlands.
  
  
  OBJECTIVE
  In the present study, we investigated the effect of mattress covers on Der p 1 and Der f 1 concentrations in dust samples in three areas in the Netherlands; Groningen, Utrecht and Rotterdam.
  
  
  METHODS
  Dust was obtained from mattresses of 277 patients at the beginning of the study and after 12 months of the placebo-controlled intervention. It was analysed for allergen content by immunoassay. The differential effect of the intervention on Der p 1 vs. Der f 1 was analysed in a subgroup with Der p 1+Der f 1>1 microg/g dust (N=161). It was tested whether the intervention caused a significant change in the Der f 1/Der p 1 ratio.
  
  
  RESULTS
  At t=0 we found very similar levels of the group 1 allergens of both species. The relatively high prevalence of D. farinae in our study was geographically restricted: the median Der f 1/Der p 1 ratio was 11.1 in the Rotterdam area compared with 1.32 in the Utrecht area and 0.33 in the Groningen area. Analysis of our data showed that the favourable intervention effect found for the combined allergen data (reduction factor=2.9, P<0.001) is essentially due to a favourable effect of the intervention on the Der f 1 levels only (reduction factor=3.6, P<0.001). The effect on the Der p 1 level was remarkably small (reduction factor: 1.2, P=0.48). In the intervention group, the Der f 1/Der p 1 ratio decreased after 12 months by a factor 2.0, whereas in the placebo group it increased (probability of the intervention effect: P<0.005).
  
  
  CONCLUSIONS
  Mite-impermeable covers are more effective in reducing the level of Der f 1 than that of Der p 1.
authors.affiliation: Department of Allergology, University Hospital, Groningen, The Netherlands.
authors.forename: Z
authors.initials: Z
authors.lastname: Tempels-Pavlica
authors.forename: A J
authors.initials: AJ
authors.lastname: Oosting
authors.forename: I
authors.initials: I
authors.lastname: Terreehorst
authors.forename: R Gerth
authors.initials: RG
authors.lastname: van Wijk
authors.forename: C A F M
authors.initials: CA
authors.lastname: Bruijnzeel-Koomen
authors.forename: J G R
authors.initials: JG
authors.lastname: de Monchy
authors.forename: R C
authors.initials: RC
authors.lastname: Aalberse
mesh_terms: D000485:Allergens / Q000032:analysis*; D000818:Animals; D039741:Antigens, Dermatophagoides / Q000032:analysis; D060829:Arthropod Proteins; D001512:Bedding and Linens; D003546:Cysteine Endopeptidases; D040001:Dermatophagoides farinae / Q000276:immunology; D040002:Dermatophagoides pteronyssinus / Q000276:immunology*; D004311:Double-Blind Method; D004391:Dust / Q000276:immunology*; D004781:Environmental Exposure / Q000517:prevention & control; D009426:Netherlands
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; D004391:Dust; D003546:Cysteine Endopeptidases; C451159:Dermatophagoides farinae antigen f 1; C451162:Dermatophagoides pteronyssinus antigen p 1