Ben Vaughn

Differential effects of outdoor versus indoor fungal spores on asthma morbidity in inner-city children.

BACKGROUND Although sensitization to fungal allergens is prevalent in inner-city children with asthma, the relationship between fungal exposure and morbidity is poorly understood. OBJECTIVE We examined relationships between fungal sensitization, exposure, and asthma morbidity in inner-city children. METHODS Participants were 5 to 11 years old and enrolled in the Inner-City Asthma Study. This report includes the subset of children with at least 1 positive skin test (PST) response to a fungal allergen extract; for these children, indoor and outdoor airborne culturable fungi levels were measured at baseline and throughout the 2-year study. Asthma morbidity measures were collected prospectively. The primary outcome was symptom days per 2 weeks. RESULTS At baseline, children with a PST response to a fungal allergen extract had significantly more symptom days compared with those without a PST response to any fungal allergen extract (6.3 vs 5.7 days per 2 weeks, P = .04). During the study, increases in total fungal exposure and indoor Penicillium species exposure were associated with increases in symptom days and asthma-related unscheduled visits. Indoor exposures to total fungi and to Penicillium species were associated with significant increases in unscheduled visits, even after controlling for outdoor fungal levels. Adverse effects associated with exposure to a specific fungus were stronger among children with PST responses to that fungal allergen extract compared with those seen in children with negative skin test responses. CONCLUSION Outdoor fungal exposure is primarily associated with increased asthma symptoms and increased risk of exacerbations in this population.

Feasibility of Using Subject-Collected Dust Samples in Epidemiologic and Clinical Studies of Indoor Allergens

Studies of indoor allergen exposures are often limited by the cost and logistics of sending technicians to homes to collect dust. In this study we evaluated the feasibility of having subjects collect their own dust samples. The objectives were to compare allergen concentrations between subject- and technician-collected samples and to examine the sample return rate. Using a dust collection device and written instructions provided to them by mail, 102 subjects collected a combined dust sample from a bed and bedroom floor. Later the same day, a technician collected a side-by-side sample. Dust samples were weighed and analyzed for the cat allergen Fel d 1 and the dust mite allergen Der p 1. Fifty additional subjects who were enrolled by telephone were mailed dust collection packages and asked to return a dust sample and questionnaire by mail. A technician did not visit their homes. Correlations between subject- and technician-collected samples were strong for concentrations of Fel d 1 (r = 0.88) and Der p 1 (r = 0.87). With allergen concentrations dichotomized at lower limits of detection and clinically relevant thresholds, agreements between methodologies ranged from 91 to 98%. Although dust weights were correlated (r = 0.48, p < 0.001), subjects collected lighter samples. Among the group of 50 subjects, 46 returned a dust sample and completed questionnaire. The median number of days to receive a sample was 15. With some limitations, subject-collected dust sampling appears to be a valid and practical option for epidemiologic and clinical studies that report allergen concentration as a measure of exposure.

Comparison of enzyme immunoassay-based assays for environmental Alternaria alternata.

BACKGROUND Alternaria alternata-derived allergenic materials are causes of human disease. Several immunoassays exist to quantify these materials. OBJECTIVE To compare methods for evaluating Alternaria content. METHODS Four methods, including 1 monoclonal antibody (MAb)-based assay specific for recombinant Alt a 1, 1 MAb-based assay for chromatographically purified Alt a 1, 1 polyclonal antibody (PAb)-based assay for chromatographically purified Alt a 1, and 1 PAb-based assay for whole Alternaria extract, were evaluated. Environmental samples collected as part of the National Survey of Lead and Allergens in Housing were examined. Alternaria spore counts were determined in dust by observation. RESULTS The MAb-based assay for recombinant Alt a 1 detected Alternaria in few samples (25%); the PAb-based assay for whole Alternaria proteins detected antigen in 97% of the samples. The PAb- and MAb-based assays for purified Alt a 1 detected antigen in 100% of the samples. There was a significant positive correlation between the 2 assays directed against purified Alt a 1. There was a positive correlation between the PAb-based assay for whole Alternaria and the PAb-based assay for Alt a 1. Nearly all the dust samples contained Alternaria spores, and there was a strong positive correlation between counts and all assays. CONCLUSION Because of the multifaceted nature of Alternaria, the disparities between methods for quantifying Alternaria, the cross-reactivity between fungal allergens, and the documented genetic promiscuity of this fungus, enzyme immunoassays using PAbs against a range of Alternaria proteins will probably produce the most reliable estimation of overall Alternaria exposure in house dust.