Domestic exposure to fungal allergenic particles determined by halogen immunoassay using subject's serum versus particles carrying three non-fungal allergens determined by allergen-specific HIA

Abstract

Studies that estimate indoor aeroallergen exposure typically measure a pre-selected limited range of allergens. In this study, inhalable aeroallergen particles were quantified using the halogen immunoassay (HIA) to determine the contribution of fungal and non-fungal aeroallergens to total allergen exposure. Bioaerosols from 39 homes of fungal-allergic subjects were sampled using inhalable fraction samplers and immunostained by HIA using resident subject's immunoglobulin E (IgE) to detect allergen-laden particles. Fungal aerosols as well as particles carrying mite, cat, and cockroach allergens were identified and enumerated by HIA. Reservoir dust-mite (Der p 1), cat (Fel d 1), and cockroach (Bla g 1) allergen concentrations were quantified by ELISA. Fungal particles that bound subject's IgE in the HIA were 1.7 (bedroom)- and 1.4 (living room)-fold more concentrated than Der p 1, Fel d 1, and Bla g 1 allergen particles combined. Predominant fungal conidia that bound IgE were derived from common environmental genera including Cladosporium and other fungi that produce amerospores. Airborne mite, cat, and cockroach allergen particle counts were not associated with reservoir concentrations determined by ELISA. This study demonstrates that inhalable fungal aerosols are the predominant aeroallergen sources in Sydney homes and should be considered in future exposure assessments. Indoor allergen exposure assessment studies have primarily focused on a limited range of allergen sources in samples derived from reservoir dust samples. Using an innovative immunodiagnostic approach, this study demonstrates that fungal bioaerosols are the dominant source of aeroallergen exposure in the domestic environment, providing unique insight into domestic aeroallergen exposure.