What characterizes house dust mite sensitive individuals in a house dust mite free community in Reykjavik, Iceland?
BACKGROUND
Previous studies show that 6-9% of young adults in Reykjavik are sensitised to the house dust mite (HDM) Dermatophagoides pteronyssinus (D. pteronyssinus). However, only negligible amounts of HDM and HDM allergens were detected in their homes. The study investigates what characterizes these individuals.


METHODS
We investigated all participants in the European Community Respiratory Health Surveys I and II (ECRHS I and II) with D. pteronyssinus specific IgE, in the years 1991-92. A grass positive but D. pteronyssinus negative control group was recruited from the same cohort. A detailed questionnaire was administered and the specific IgE (Pharmacia CAP system) against six D. pteronyssinus cross-reactive allergens was measured.


RESULTS
Of 601 ECRHS I participants with available IgE results, 88% returned for ECRHS II, 8.4 years later. Of 49 individuals with D. pteronyssinus specific IgE in ECRHS I, 24 had become negative in ECRHS II. Compared with controls, HDM sensitive subjects were more often men who had lived on farms or kept aquaria fish in childhood. Of those with specific IgE against D. pteronyssinus in ECRHS I and II, 75% had detectable IgE antibodies (>or=0.35 kU/l) to cross-reactive allergens compared with none in the control group (p<0.0001): Lepidoglyphus destructor (L. destructor) (67%), shrimp (58%), cockroach (33%), mosquito (17%), tropomyosin (17%) and blood worm (4%).


CONCLUSIONS
Icelanders with specific IgE to D. pteronyssinus are more often men who spent time on farms in childhood and today have high prevalence of IgE antibodies cross-reactive to D. pteronyssinus.
Adalsteinsdottir
Berglind
B
Department of Immunology, Landspitali-University Hospital, Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
Sigurdardottir
Sigurveig Th
ST
Gislason
Thorarinn
T
Kristensen
Bjarne
B
Gislason
David
D
D000328:Adult; D000382:Agricultural Workers' Diseases / Q000453:epidemiology / Q000276:immunology; D000818:Animals; D000845:Annelida / Q000276:immunology; D003058:Cockroaches / Q000276:immunology; D003429:Cross Reactions; D009033:Culicidae / Q000276:immunology; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000097:blood / Q000209:etiology*; D007055:Iceland / Q000453:epidemiology; D007073:Immunoglobulin E / Q000097:blood; D008297:Male; D008875:Middle Aged; D033561:Penaeidae / Q000276:immunology; D039981:Pyroglyphidae / Q000276:immunology*; D014335:Tropomyosin / Q000276:immunology
D014335:Tropomyosin; D007073:Immunoglobulin E