Allergy, Asthma, and Immunology Meeting Research Update

February 26, 2013

Increased exposure to polycyclic aromatic hydrocarbons in air pollution is associated with certain immune system effects and asthma diagnosis, according to research reported the 2013 Annual Meeting of the American Academy of Allergy, Asthma & Immunology.

Increased exposure to polycyclic aromatic hydrocarbons (PAHs) in air pollution is associated with certain immune system effects and asthma diagnosis, according to research reported the 2013 Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI), held this past week in San Antonio.

Researchers from Stanford University and the University of California, Berkeley, studied a sample of children from Fresno, a city known for high levels of PAH in outside air pollutants, to assess the effects of PAH exposure on the immune system and the occurrence of new asthma cases. Questionnaires and spirometry were given to 332 children aged 10 and 18 years, and statistical analysis was used to calculate PAH exposure levels. For some children, total immunoglobulin E (IgE) levels were determined and regulatory T cells were separated from blood samples.

Higher levels of PAH exposure were linked to increased total IgE levels. Significantly weakened regulatory T cell function also was observed in children who had been exposed to higher amounts of PAH.

There was an apparent association between PAH exposure accumulated over the previous 3 months analyzed and the diagnosis of asthma. An asthma diagnosis also appeared to be correlated with total IgE levels.

As a result, the researchers hypothesized that exposure to high PAH quantities may be having an effect at the molecular level, possibly leading to new cases of asthma.

A person may be exposed to PAHs through a variety of agents, including vehicle exhaust fumes, wildfires, wood-burning stoves, fossil fuel combustion, barbecued meats, and cigarette smoke, it was noted.

Other research results reported at the AAAAI meeting includes the following:

• Omalizumab, an immunomodulator medication currently used to manage severe allergic asthma in patients 12 years of age and older, also appears safe and effective in treating patients with chronic hives who are not successfully treated with antihistamines. The results of 2 other phase III trials should be available later this year and will help define the ultimate efficacy and safety of omalizumab, as well as the most appropriate dosing regimen, for chronic hives, it was noted.

• The rates of allergic disease-asthma, eczema, hay fever, and food allergy-are lower in children born outside of the United States than in those born in the country, but this reduced prevalence is reversed after prolonged US residence, researchers found. In addition, the rates of all of these allergic diseases were lower in the children who had parents who also were not US-born than in those whose parents were US-born. The research showed that the probability of developing eczema and hay fever is higher in children whose birthplace was outside the United States who then lived in this country for more than 10 years than in those who had lived here for up to 2 years, although this was not found to be true for asthma or food allergy. The researchers suggested that this loss of childhood protection from eczema and hay fever after extended US residence implies that environmental factors may promote the development of allergic disease.

• In a study of aspirin-exacerbated respiratory disease (AERD), a questionnaire to record self-reported respiratory reactions to alcohol consumption, such as nasal congestion and wheezing, was given to the participants. Both upper and lower respiratory reactions after ingesting alcohol appeared more frequently in patients with a diagnosis of AERD through an aspirin challenge than in asthmatics who can tolerate aspirin, aspirin-tolerant patients with rhinitis, and healthy controls.

• In overweight or obese children who experience anaphylaxis, the lower thigh may be a more favorable site for administering epinephrine than the upper thigh. Delivering epinephrine into the muscle allows for more rapid absorption and leads to higher blood levels than injecting it into the overlying fat, it was suggested, and considering the rising rates of obesity in children, there is concern that epinephrine auto-injectors will not adequately deliver the medication in overweight children who may be experiencing anaphylaxis.

• A population of children living in the southeastern United States who had anaphylaxis or hives 3 to 6 hours after eating meat were studied to see whether they also have immunoglobulin E (IgE) to alpha-gal, a carbohydrate in meat. After testing, 45 children with IgE for alpha-gal and a history of previously unexplained recurring hives or anaphylaxis were identified.

• Weight and body mass index (BMI) percentiles are lower in food-allergic children than in their non–food-allergic peers, and this impaired growth could be tied to the removal of foods from their diets, researchers found. The percentiles for height and weight were lower in children with more than 2 food allergies than in those who had 1 or 2 food allergies. Also, the percentiles for weight and BMI were lower in milk-allergic children than in those with other food allergies. These relationships between food-allergic children and the examined growth markers emphasize the need for nutritional assessment and intervention to ensure that food allergies do not contribute to growth delay, it was noted.

• In an observational study about the circumstances surrounding the purposeful exposure of food-allergic children to known food allergens that lead to a reaction, 42% of the participating families who responded indicated that they thought that small exposures would not cause symptoms and 38% said that the child had tolerated food in baked or processed form. The researchers suggested that these misconceptions about food allergy among parents and other caregivers identify a need for further education and guidance from health care professionals.

• Researchers hypothesized that changing the natural microorganism content in the gut through antibiotic use in infants might play in role in the rising prevalence of childhood food allergy. To test this, they examined South Carolina Medicaid billing data to identify children born with a food allergy diagnosis between 2007 and 2009. The children were matched 1 to 4 by age, sex, and race to controls who did not food allergy. Statistical analysis appeared to show that antibiotic exposure in the first year is linked to an increased risk of food allergy, with multiple courses of antibiotics presenting a greater risk.