The likelihood that the tick bite causes an allergy to red meat may be higher than expected

SAN FRANCISCO, CA – Until now, it was thought that for a tick to trigger an allergic immune reaction to alpha-gal in humans, it had to be recently fed with the blood of a mammal, rich in alpha-gal. New research from the UNC School of Medicine presented at the annual conference of the American Academy of Allergy, Asthma and Immunology (AAAAI) in San Francisco shows that this may not be the case .

Alpha-gal is a sugar found in most mammalian blood, except in humans. When humans develop an allergic immune response to it, this response can lead to an allergy to red meat called alpha-gal syndrome (AGS).

"Our initial hypothesis was that humans developed allergy after being exposed to alpha-gal through a tick that had been fed to a deer, from a dog or other small mammal carrying alpha-gal, "said Dr. Scott Commins, badociate professor of pediatric medicine at the UNC School of Medicine. "These new data suggest that ticks can induce this immune response without requiring the mammalian blood meal, which probably means that the risk of each bite leading to allergy is higher than expected."

To achieve these results, the researchers cleared the white blood cells of their immunoglobulin E (IgE) antibodies produced by the immune system during an allergic reaction. The cleared white blood cells were then primed with plasma from individuals with AGS and without AGS. Then, the researchers added to the cells a salivary gland extract of ticks from four species of ticks – Lone Star, Deer, Gulf Coast and American Dog. Some of the ticks were recently fed blood containing alpha-gal, others not.

As predicted by the researchers, the saliva of the Lone Star and Deer ticks that have recently been fed on blood has provoked a reaction. However, the saliva of these same types of ticks that had not fed on blood recently also provoked a reaction. The saliva of a Lone Star tick that had not been fed recently caused a reactivity 40 times greater than that of the control. Neither the type of saliva on the Gulf Coast nor the ticks of the American dog provoked a reaction.

As the saliva samples of ticks fed with blood and not blood in these experiments showed a range of reactivity, Commins states: "These results suggest that more tick bites than we initially thought could pose a risk of developing an allergy to red meat. "

There is no treatment for AGS, other than avoiding foods and products that cause a reaction. Commins urges everyone to take precautions to avoid tick bites.

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The UNC School of Medicine (SOM) is the largest state medical school and trains about 180 new physicians a year. She is consistently ranked among the top medical schools in the United States and among the best funded for her research efforts. Two UNC SOM faculty members were awarded the Nobel Prize.

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