Limited genetic control of specific IgE responses to rye grass pollen allergens in Australian twins

Background Both genetic and environmental factors are thought to contribute to specific IgE responses, however, the relative contribution of each in the responses to individual ryegrass pollen allergens is largely unknown even though some responses to allergens have been linked to certain HLA complexes. Objective Using a large group of monozygotic and dizygotic twins, this study designed to investigate the IgE binding profiles of individual ryegrass pollen (Lolium perenne) components to assess the relative contribution of genetic and environmental factors in determining IgE responses to specific allergens. Methods Ryegrass pollen proteins were separated by electrophoresis and immunoblotted with sera from 191 pairs of twins where at least one sibling had a SPT \u3e 2 mm to perennial ryegrass. Concordance levels for individual ryegrass pollen components were compared between monozygotic and dizygotic twins in a subset group where both twins had SPT \u3e 3 mm to perennial ryegrass. Results Immunoblotting revealed 23 individual IgE-binding components from ryegrass pollen, Although there was a significantly greater proportion of monozygotic twins with SPT wheals greater than 3 mm when compared with the dizygotic twins, the mean case-wise concordance for the immunoblot components was similar for both groups of twins. The mean case-wise concordance when at least four pairs of sera were involved was 44% for the MZ twins (n = 11 components) and 45% for the DZ twins (n = 12 components). We found no significant differences in concordance levels for any of the 23 individual components including allergens previously-associated with HLA. Conclusion Evidence for genetic control of allergen-specific IgE responses in a large population sample of twins to individual ryegrass allergens is limited, indicating that the ISE responses to specific ryegrass pollen allergens are determined largely by environmental factors

Immunoblotting analysis of twin sera provides evidence for limited genetic control of specific IgE responses to house dust mite allergens

Background: Although some studies have shown genetic control of specific IgE responses to purified grass allergens, studies with other allergens have not supported this. The extent of such control for house dust mite (HDM) (Dermatophagoides pteronyssinus) allergens is unclear. Objective: We sought to determine the extent to which genetic factors control the specificity of IgE responses to individual HDM allergens by comparing the immunoblot patterns of IgE binding of serum from monozygotic and dizygotic members of a large cohort of Australian twins. Methods: HDM proteins separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis were immunoblotted with sera from 317 twin pairs in which at least one twin had at least a weak HDM skin test response. Concordance levels for IgE binding to the individual HDM components were compared in the subset of 142 pairs of twins in which both twins were allergic to HDMs (skin prick test wheal diameter, \u3e 3 mm). Results: Over all 36 blotted bands, the mean case-wise concordance was 41% for monozygotic twins and 17% for dizygotic twins. Of the components detected, only those of molecular weights 23 kd and 16 lid mere significantly different between the groups (p \u3c 0.01). Differences observed between the monozygotic and dizygotic twins could be partly explained by overall IgE hyperresponsiveness. Conclusion: Evidence for genetic control of IgE responses to 36 IgE-binding HDM components from a large sample of twins showed significant differences in concordance for two components and nonsignificant differences for several others. In the monozygotic twins, concordance never exceeded 67% for any band, and most monozygotic individuals recognized components their co-twin did not. Genetic control of overall atopy in monozygotic twins is far stronger than that controlling specific sensitization to HDM allergens

London Plane Tree bioaerosol exposure and allergic sensitization in Sydney, Australia

Exposure to London Plane Tree (Platanus) bioaerosols in Sydney, Australia has been anecdotally linked to respiratory irritation, rhinitis, and conjunctivitis. To determine the relationships between Platanus bioaerosol exposure, allergic sensitization, and symptoms. Sixty-four subjects with self-reported Platanus symptoms were recruited from inner-urban Sydney. Allergic sensitization was determined by skin prick test (SPT) to 13 allergens. Airborne concentrations of Platanus pollen, trichomes, and achene fibers, and other pollen and fungal spores, were measured over the spring and summer of 20062007. Subjects' allergic symptoms were monitored concurrently. The Halogen immunoassay (HIA) was used to measure subjects' immunoglobulin E (IgE) reactivity to collected bioaerosols. Platanus pollen constituted 76% of total pollen between July 2006 and April 2007. Airborne concentrations of Platanus pollen peaked from August until October. Non-Platanus pollen peaked from July to December. Elevated concentrations of trichomes and achene fibers occurred from September to December and August to October, respectively. As determined by SPT, 85.9% of subjects were sensitized, 65.6% to any pollen tested, 56.3% to Lolium perenne, and 23.4% to Platanus. Higher mean daily symptom scores were only associated with high counts of non-Platanus pollens. HIA analysis demonstrated IgE binding to Platanus pollen in all Platanus sensitized subjects. Personal nasal air sampling detected airborne trichomes that were capable of being inhaled. Platanus trichomes or achene fibers did not bind IgE from any subject. Platanus bioaerosols exist in high concentrations between August and November in inner-urban Sydney but were not associated with seasonal symptoms. Platanus trichomes are inhaled and may constitute a respiratory irritant

Most Personal Exposure to House Dust Mite Aeroallergen Occurs during the Day

<div><p>Background</p><p>The bed is commonly regarded as the main site of house dust mite exposure; however this has not been directly established by continuous measurements. The objective of this study was to determine the pattern of personal exposure to mite aeroallergen over 24 hours.</p> <p>Methods</p><p>12 adults each collected 9 sequential samples (8 during the day, mean 115 mins, and one overnight, mean 514 mins) over 24 hours using a portable air-pump (2L/min) connected to an IOM filter located on the shoulder during the day and on the bed head overnight. Samples were analysed for mite allergen Der p 1 by ELISA. Location and activity were recorded. A mixed model analysis was performed to determine exposure as a function of 14 categories of activity.</p> <p>Results</p><p>Personal aeroallergen exposure differed widely over time, both within and between subjects. The highest average exposure (1117 pg/m³, 95% CI: 289-4314) occurred on public transport and the lowest overnight in bed (45 pg/m³, 95% CI: 17-17), which contributed only 9.8% (95% CI: 4.4%-15.1%) of total daily exposure. Aeroallergens were not related to bed reservoirs.</p> <p>Conclusion</p><p>The study challenges the current paradigm that the bed is the main site of HDM exposure and instead suggests most exposure occurs in association with domestic activity and proximity to other people. Effective mite interventions, designed to improve asthma outcomes, need to first identify and then address the multiple sources of aeroallergen exposure.</p> </div

Average personal exposure (<b>pg/m</b>^<b>3</b>) <b>for the nine sequential periods over 24 hours.</b>

<p>Periods 1-8 occurred over the day at approximately 2 hour intervals between 7:00am and 10:30pm and Period 9 was overnight (~8 hours). Each symbol represents a separate subject. One subject (5) who collected samples during the working week and again at the weekend is shown as subject 5(2).</p

The relative quantities and rates of exposure in the eight categories of location encountered in the 24 hour period.

<p>The relative quantities and rates of exposure in the eight categories of location encountered in the 24 hour period.</p

Images of the sampler and disk as used for particle collection.

<p>(A) The sampler as worn on shoulder strap of a small backpack containing the airpump; the arrow indicates the location of the time-lapse camera. (B) Close-up of the sampler; the arrow indicates the inlet. (C) An adhesive disk following collection for approximately 11.5 hours. The large arrows indicate the green and red powder used to mark the start and stop of sampling and smaller white arrows indicate visible bands of dust particles impacted during periods of high exposure. The numbers on the inner face are used to visually check the process during sampling.</p

Plots of participant’s average exposures at discrete intervals over approximately 24 hours.

<p>The times of sampling have been aligned; midnight is shown as the vertical heavy dotted line. A lighter dotted line is used to separate samples that had similar quantities of exposure. The plots are annotated to nominate some of the activities or places. Where an average exposure exceeded the Y axis, it is denoted as a number above the gap in the plotted line. (A) The exposures of participants number 1–8 who collected samples over a single day and night period. The asterisk, i.e., ‘*B/R’ indicates that the person was in the bedroom but not sleeping, e.g. on computer, reading etc. Note different participants have a Y axis (exposure) maxima varying from 250–2000 pg/m³. (B) The exposures during eight collection periods by participant 9. Two part-days are shown on a single graph separated by a horizontal line; a third part-day is not shown. (C) The exposures during four collections made by participant 10. Both (B) and (C) use a maximum value on the Y axis of 500 pg/m³. Additional details of locations are tabulated in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0153414#pone.0153414.s003" target="_blank">S1 Table</a>.</p