The American Academy of Allergy, Asthma, and Immunology (AAAAI) annual meeting may have been cancelled, but more than 800 abstracts were scheduled for presentation and are now published. Here are some of the highlights regarding allergies to pollen, pets, and household dust.

School Desktops, Cafeteria Floors: What’s in That Dust?

Many parents of food-allergic children know all too well that, no matter what precautions they take, their kids will develop symptoms seemingly at random. One reason for that is the sheer ubiquity of allergic foods such as peanuts, eggs, and dairy products.

Schools may take great care to keep peanuts out of the environment and to label cafeteria foods so that allergic children can avoid what they need to; but is that enough? A group led by Michelle Maciag, MD, of Boston Children’s Hospital, took a closer look at the school environment to determine where food allergens may lurk (AAAAI abstract 577). The group went to 18 elementary schools and took 88 vacuumed samples of floor dust and 87 wipes of desks and cafeteria tables, analyzing them for common food allergens.

The results might shock school administrators and janitorial staff, not to mention parents. Rates of positive findings in floor dust and table/desk wipes, respectively, were as follows:

• Milk-Bos d 5: 100%, 100%
• Peanut-Ara h 3: 64.8%, 93.1%
• Peanut-Ara h 6: 93.1%, 98.9%
• Egg-Gal d 1: 85.2%, 73.6%
• Egg-Gal d 2: 100%, 77.0%
• Cashew-Ana o 3: 79.5%, 98.9%
• Hazelnut-Cor a 9: 44.3%, 31.0%

Milk allergens showed the highest levels, with a median of 26 μg/g in dust.

Maciag and colleagues noted, however, that the study didn’t determine whether children’s likely exposures to these allergen sources were sufficient to trigger reactions.

Allergy Testing in IgE-Deficient Patients

Most allergies are marked by high levels allergen-specific immunoglobulin E (IgE), but a subgroup of people are deficient in IgE generally, which can confound standard allergy testing. It’s particularly common in individuals who report chronic upper respiratory symptoms; IgE deficiency may actually promote such symptoms, although that’s not certain.

An open question has been whether standard skin-prick or intradermal allergen testing has any benefit in IgE-deficient individuals. Now a group at Montefiore Medical Center in New York City, led by Barrie Cohen, conducted a systematic review of skin and blood test results in such patients to fill that gap.

In their AAAAI abstract (483), Cohen’s group reported findings from 71 IgE-deficient individuals with respiratory symptoms who underwent standard skin tests and/or serum-specific IgE tests.

The main result: 30% of these patients had positive results on skin-prick or intradermal testing. Although this was markedly lower than the rate in patients with normal or high overall IgE levels (69% and 93%-94%, respectively), it was enough for Cohen and colleagues to conclude that “[a]llergen-specific tests are useful to diagnose environmental sensitizations and prescribe immunotherapy in IgE-deficient individuals.”

CRISPR Promising for Non-Allergenic Cats

More than 10% of the population is allergic to cats, and particularly to a salivary protein known as Feld1. Development of a Feld1-free cat could have a number of benefits for cat-lovers and non-lovers alike. Several approaches have been tried, including conventional breeding and in vitro gene-knockout technologies, but with incomplete success so far.

The newer and more powerful genome-engineering technology known as CRISPR may yield better results because it can delete target genes from the germline entirely, such that offspring of a CRISPR-edited animal will also lack the unwanted gene. That’s the task taken on by a group at Indoor Biotechnologies in Charlottesville, Virginia, whose AAAAI abstract (501) reported a promising initial effort.

It’s important to note that the researchers didn’t generate any live Feld1-free cats — this was just an in vitro study. Led by Nicole Brackett, the group first determined the appropriate sequences to delete, in particular those that were conserved among different animals. CRISPR was then employed to delete those sequences in feline cells. This was successful, the group said, with “no evidence of off-target” editing at other genomic sites the researchers thought might be susceptible.

Misdiagnosis of Tree Nut Allergy

“Pollen-food syndrome” (PFS) is a recognized phenomenon in which patients find themselves allergic both to certain foods and certain types of pollen, driven by molecular similarities in the culprit antigens. Birch trees seem to be a particular problem in PFS; something like one-third of people living in areas with large birch populations are allergic to their pollen. Past research has suggested that cross-reactivity between birch pollen and some tree nuts, especially hazelnuts, is common.

Researchers at McGill University in Montreal led by Danbing Ke examined the degree to which patients previously diagnosed with hazelnut allergy may actually suffer from PFS related to birch pollen — such that they may not be severely allergic to the nuts and may be making unnecessary lifestyle alterations.

According to the group’s AAAAI abstract (744), Ke and colleagues performed double-blind, placebo-controlled food challenges in nine children and teens with hazelnut allergy diagnoses (median age 15, IQR 9-17) as well in 22 with peanut allergy (median age 12, IQR 10-14), who served as controls. Six of the allegedly hazelnut-allergic participants didn’t react to hazelnuts in the testing; adverse reactions that did occur were all mild and none of the patients needed epinephrine. On the other hand, all the peanut-allergic participants reacted, with 21 developing anaphylaxis and 16 receiving epinephrine injections.

Ke and colleagues concluded that food challenge testing should be standard to confirm any diagnosis of hazelnut allergy.

Genetic Link Between Dust Mite Allergy and Asthma

House dust mites are literally everywhere, but not everyone developed allergies to them; nor does every child with dust mite allergy go on to develop asthma. That has suggested the potential for human genetic variation to play a role in the well-known association between dust mite allergy and asthma. Now, a group from Korea has found a strong candidate gene (AAAAI abstract 565).

Eun Lee and colleagues at Asan Medical Center in Seoul drew on data from 2,929 children participating in a large population-based cohort study. They found that presence of a polymorphism called rs1800629 in the gene for tumor necrosis factor-alpha more than tripled the risk for previous diagnosis of asthma among those children with dust mite sensitivity in skin prick testing (adjusted odds ratio 3.43, 95% CI 2.19-5.38). Risk of current asthma (as identified in bronchial challenge) in those with dust mite sensitivity was even greater (aOR 6.52 (95% CI 3.65-11.65) with the rs1800629 polymorphism.

The findings suggest that genetic testing could identify children at increased risk for asthma, for whom prevention strategies might be beneficial, Lee and colleagues concluded.