Prevalence of Tyrophagus putrescentiae hypersensitivity in subjects over 70 years of age in a veterans' nursing home in Taiwan.

BACKGROUND

Domestic mites are present in house dust samples throughout the world. Reports have shown a high prevalence of Tyrophagus putrescentiae (Tp) sensitization in Europe and Asia, and its importance and clinical relevance in elderly subjects have grown rapidly. The main objective of this study was to investigate the prevalence of Tp sensitization in elderly subjects in a veterans' nursing home using mite allergen extracts and recombinant allergens.

METHODS

A total of 199 subjects were enrolled in this study: 112 elderly subjects from a nursing home and 87 healthy young adults from the hospital staff as controls. The prevalence of Tp hypersensitivity was determined by specific IgE measurements and basophil histamine release. Immunoblotting with or without inhibition with Dermatophagoides pteronyssinus (Dp) was performed to identify the major allergens and species-specific allergen to Tp.

RESULTS

It was determined that 39.3% (44/112) of the elderly population were sensitized to Tp and 17.9% (20/112) to Tp alone. There was a significantly higher prevalence of Tp hypersensitivity in elderly subjects in comparison with the young adult population. In the age association study of Tp and Dp sensitization, the elderly subjects were more sensitized to Tp than to Dp (p = 0.02). Among the elderly subjects with chronic obstructive pulmonary disease (COPD) 45.8% (11/24) were Tp sensitive. The major allergens, Tyr p 2 and Tyr p 3, were identified with molecular weights of 16 kDa (53%) and 26 kDa (50%) as determined by ELISA and immunoblot inhibition analyses.

CONCLUSION

The prevalence of Tp sensitization was higher in elderly subjects, especially in patients with COPD. The high percentage of IgE-binding components to the allergens Tyr p 2 and Tyr p 3 indicated that both allergens may play a role in the pathogenesis of IgE-mediated allergic diseases in elderly populations.