House CallApr/May 2012 Issue

Research Roundup: Celiac Risks, Oral Food Challenge, Allergic to Cats, & More!

The latest medical news for people with allergies and food sensitivities

© Thinkstock 2012/iStockPhoto

© Thinkstock 2012/iStockPhoto

Predicting Celiac Risk

Adding three genes—LPP, REL, and RGS1—to the genetic test for celiac disease improved predictions about whether certain siblings of celiacs would also develop the condition, according to researchers at the University of Naples, Italy.

In recent years, researchers have identified over 40 genes thought to be involved with celiac disease; these genes are part of a different class of markers than those included in the current genetic test, which, when negative, can help rule out the likelihood of ever developing celiac disease.

Researchers say improvements in predicting the risk of celiac disease, particularly among first-degree relatives (where up to 10 percent may be affected), can help pinpoint those who may benefit from closer monitoring, ensuring a timely diagnosis.

The work was published in PloS One.

Oral Food Challenge

The gold standard for diagnosing food allergy is the oral food challenge—a medically supervised, gradual feeding of suspect foods to determine if they cause an allergic reaction. However, a study presented at the 2011 meeting of the American College of Allergy, Asthma and Immunology (ACAAI) says too few food allergies are being confirmed by oral food challenge. Among 3,339 food-allergic children identified through a large telephone survey, only 61 percent received a formal physician diagnosis and just 15 percent subsequently underwent an oral food challenge. Children may be unnecessarily avoiding certain foods, researchers said in a press release. The ACAAI recommends seeking a board-certified allergist for proper diagnosis and management of food allergy.

In other research, a team from Southampton University Hospital in the UK recently discovered that children who underwent oral food challenges (to check if they had outgrown peanut or tree nut allergies) experienced reduced anxiety and improved quality of life related to their food allergy in the months after the test—regardless of the outcome. Their mothers reported similar improvements, explaining that even if their child had a positive food challenge, they felt more informed about their child’s allergy after having it confirmed. The study, published in Clinical and Experimental Allergy, is the first to demonstrate a psychological benefit conferred by the oral food challenge.

Allergic to Cats, Allergic to Pork

If you’ve never heard of pork-cat syndrome, you’re not alone. The first known cases of this syndrome in the United States (six total) were recently documented by researchers at the University of Virginia and presented at the 2011 meeting of the American College of Allergy, Asthma and Immunology.

According to the researchers, six individuals (average age 28) experienced allergic reactions ranging from an itchy mouth and/or hives to anaphylaxis after after eating pork. All had positive IgE blood tests to pork and cat.

Researchers believe pork-cat syndrome stems from a rare type of cross-reactive allergy. More work is needed to better understand the condition, which researchers call unusual and under-recognized.

Gluten Sensitivity Test

Researchers from the University of Bologna in Italy recently reviewed the celiac test results of 80 people diagnosed with celiac disease and 78 diagnosed with gluten sensitivity to see if they could spot patterns predictive of gluten sensitivity. Currently there’s not a test for gluten sensitivity; it may be diagnosed after ruling out wheat allergy and celiac disease and then observing that symptoms resolve on the gluten-free diet.

In the study, researchers found those with gluten sensitivity (unlike those with celiac disease) were negative for all of the celiac blood tests except for anti-gliadin antibody IgG (AGA-IgG). Just over half had a positive AGA-IgG result.

Anti-gliadin antibodies (there are two types, IgG and IgA) circulate in the blood as a reaction to ingested gluten. But because AGA-IgG, in particular, may show up in people without celiac disease, this test is not highly suggestive of celiac on its own.

The researchers wrote that, although a positive AGA-IgG finding—combined with negative results on all other celiac tests—can be valuable for suspecting gluten sensitivity in patients with gluten-related symptoms, a test for gluten sensitivity is urgently needed.

The study was published in the Journal of Clinical Gastroenterology.

Note: In late 2011, researchers from the University of Maryland Center for Celiac Research launched a multi-center research study aimed at developing a test for gluten sensitivity. Stay tuned for updates on the study, which is expected to take 12 months.

Help for Peanut Allergy

Treatment for peanut and other food allergies is the subject of two new studies published in the Journal of Allergy and Clinical Immunology. In one, researchers from Mount Sinai School of Medicine in New York found soybean isoflavones—molecules with anti-inflammatory and immune-modulating properties—could suppress allergic sensitization and help protect against peanut allergy in mice. (Soybeans are a rich source of isoflavones but because of the risk of cross-reactivity—soybeans and peanuts are closely related legumes—the isoflavones used in the study first underwent an extensive purification process.)

Researchers fed peanut-allergic mice an isoflavone or control diet (isoflavone-free) for two weeks and then challenged them with peanut. The control group showed severe symptoms of anaphylaxis while the mice fed the isoflavone diet had very mild symptoms and markedly reduced levels of peanut-specific antibodies.

Lead author Madhan Masilamani, PhD, emphasizes that the research is very preliminary. “The exact mechanism of how isoflavones suppress allergy is still under investigation and is the main focus of our current research. Identifying the mechanism will be the first step towards clinical utilization of isoflavones to treat peanut allergy in humans,” he says.

In the second study, also out of Mount Sinai School of Medicine, researchers found that the Chinese herbal drug known as Food Allergy Herbal Formula-2 (FAHF-2) was safe and well tolerated in an early clinical trial with 18 food-allergic participants. Although food challenges weren’t part of the clinical trial, when participants’ blood samples were put through allergen stimulation tests, key markers were inhibited, suggesting FAHF-2 may provide a safe therapeutic option for food-allergic individuals. FAHF-2 completely blocked peanut allergy anaphylaxis in earlier work in mice. A larger clinical trial with FAHF-2 that includes food challenges is now underway.

Know Your Nuts

In a new study published in the Annals of Allergy, Asthma and Immunology, researchers from Nationwide Children’s Hospital in Columbus, Ohio, asked 1,100 visitors to a children’s science center to identify nuts from a display that included peanuts and nine tree nuts in a total of 19 different forms, such as slivered or in the shell. Overall, participants correctly identified fewer than half the nuts—children (over age 6) got 24 percent right while adults got 58 percent right. Among those participants who reported having nut allergies, just half correctly identified all forms of the nuts to which they are allergic.

“It’s often assumed that people know what nuts look like but as our study showed, they often do not,” says lead author Todd L. Hostetler, MD. “Nuts look different in their shell, out of their shell and cut up. To avoid a possible life-threatening reaction, both adults and children need to know what they are looking for as they try to avoid these nuts.”

Medical writer Christine Boyd lives in Baltimore.

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