Red Meat Allergy May Develop Due to Tick Saliva, Not Blood Meal Status

Lone Star Tick

Research presented at 2019 AAAAI Annual Meeting finds potential allergen is retained in tick saliva independent of feedings

Alpha-gal syndrome (AGS), a food allergy commonly known as red meat allergy, may develop from ticks’ saliva itself, whether a tick has fed on another animal before biting a human or not. This news comes from a study presented for the first time at the 2019 Annual Meeting of the American Academy of Allergy, Asthma & Immunology.

Alpha-gal is not naturally present in humans, though it is in virtually all other mammals. According to first author Scott P. Commins, MD, PhD, “These results suggest that more tick bites than we initially suspected could pose a risk for developing red meat allergy. Our original hypothesis was that humans developed the allergy after being exposed to alpha-gal through a tick that had fed on a deer, dog or other small mammal that has alpha-gal. This new data suggests that ticks can induce this immune response without requiring the blood meal, which likely means the risk of each bite potentially leading to the allergy is higher than we anticipated.”

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Researchers stripped white blood cells of Immunoglobulin E (IgE), antibodies that are produced during an allergic reaction. After being primed with plasma from individuals both allergic and not allergic to alpha-gal, tick salivary gland extract was introduced from four species of ticks.

Reactivity was 40 times higher when alpha-gal IgE sensitized cells were introduced to tick salivary gland extract from Lone Star Ticks compared to the baseline. Reactions were also found in Ixodes scapularis but not Amblyomma maculatum (the Gulf Coast tick).

There is currently no treatment for red meat allergy beyond avoiding the consumption of red meat and in some cases, dairy and gelatin. Fortunately there is a chance this allergy may resolve over time if the individual avoids another tick bite. As research advances there is hope a better treatment of red meat allergy will be found. Until then, experts urge everyone to take normal precautions when it comes to preventing tick bites.

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Visit aaaai.org to learn more about alpha-gal. Research presented at the AAAAI Annual Meeting, February 22-25 in San Francisco, California, is published in an online supplement to The Journal of Allergy and Clinical Immunology.

The American Academy of Allergy, Asthma & Immunology (AAAAI) represents allergists, asthma specialists, clinical immunologists, allied health professionals and others with a special interest in the research and treatment of allergic and immunologic diseases. Established in 1943, the AAAAI has nearly 7,000 members in the United States, Canada and 72 other countries. The AAAAI’s Find an Allergist/Immunologist service is a trusted resource to help you find a specialist close to home.

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