Here’s What Happens to Your Body During Anaphylaxis

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According to the Centers for Disease Control and Prevention, allergies affect more than 50 million Americans every year—and anaphylaxis, the most severe allergic reaction, affects at least 1.6 percent of the general population [PDF]. Here’s the science of what happens to the body during anaphylactic shock.

ALLERGEN EXPOSURE

In a person with allergies, cells sometimes identify foreign but innocuous stimuli as major threats. Why some people are allergic to certain things while others are not is a mystery science hasn't yet solved, but we do know how it happens: through a process called sensitization.

Here’s how it works. When the body encounters a foreign substance, also called an antigen, immune system cells deliver some of substance's molecules to T-helper cells living in the lymph nodes. Those cells also bring along a type of molecule that informs a T-helper cell it’s time to stage an immune response. Known as a costimulatory molecule, it's necessary to activate any type of immune system reaction involving T cells, whether you have allergies or not.

Being exposed to an antigen "primes" a T-helper cell, turning it into a Th2 cell. Primed Th2 cells release proteins called interleukins, which do two things: First, they interact with another type of immune cell called B cells to produce infection-fighting antibodies that bind to mast cells, which contain chemical particles they'll release in the presence of an antigen. Second, the interleukins activate eosinophils, a type of white blood cell that discharges toxic substances to destroy invading cells (and, occasionally, host cells). In this process, the immune system identifies the "threat" and deploys cells prepared to fight it. The immune system's elevated level of awareness of and preparation against the antigen reclassifies the substance as an allergen—a considerably more dangerous threat.

Because an allergy only develops after this process, a person allergic to strawberries, for example, will only experience a reaction the next time they eat something containing strawberries. New allergies can pop up at any point in your life.

An immune system on allergies is a little bit like a brain that can't distinguish a piece of lint from a spider: unable to relax, constantly on guard against every potential threat. After initial exposure, the mast cells activated during the sensitization phase are still equipped with allergen-specific antibodies and remain combat-ready, prepared to respond immediately should a second exposure ever occur. If it does—and it probably will—here’s what you can expect to happen.

ALLERGIC REACTION

If two or more allergen molecules bind to a sensitized mast cell, the mast cell releases inflammatory mediators that produce an allergic reaction. These mediators include substances like histamine and more of the interleukins that, in turn, activate eosinophils, Th2 cells, and basophils (another type of white blood cell). In a non-allergic reaction, mediators produce helpful inflammation that prevents infection and initiates healing—but those same symptoms can be annoying and even dangerous when the immune system attacks an otherwise benign allergen. Mast cells also release leukotrienes, which recruit more immune cells to the area and speed up the reaction. That leads to what Stanford University researcher Tina Sindher calls a “‘chain reaction’ of allergic inflammation.”

With the release of histamine, you might experience both bronchial contraction—which makes it more difficult to breathe—and blood vessel dilation. The latter makes it easier for blood to flow to affected areas, but it also makes blood vessels more permeable, allowing blood to escape from the blood vessel walls and flow into the spaces between cells and causing swelling and hives.

For most, these symptoms are merely uncomfortable; they can occur as late as eight to 12 hours after initial exposure, long after the allergen is gone, and can be alleviated with an antihistamine like Benadryl. But for a person with severe allergies, a life-threatening allergic response can occur within minutes: Their airways will constrict so much they won't be able to breathe, and their blood vessels will be unable to contract, which can lead to a drop in a blood pressure and keep veins from getting blood back to the heart. The combination of airway constriction and blood vessel dilation can make it impossible for the body to supply enough oxygen to major organs—that's anaphylactic shock.

The only way to stop anaphylaxis in its tracks is with epinephrine, more commonly known as adrenaline. Adrenaline is a hormone naturally produced by the adrenal glands to help generate the "fight or flight" response in emergency situations. It works by constricting certain blood vessels, increasing blood pressure, and relaxing airways, counteracting all the reactions produced by histamines.

According to Sindher, it’s important to use epinephrine immediately if you're at risk for anaphylactic shock. “There’s a general belief out there that epinephrine should only be used in the worst-case scenario,” she tells Mental Floss. “In fact, most of the complications we see in food allergic reactions are due to delayed use in Epi. Antihistamines can be helpful in treating the symptoms of itching and congestion, but they do not help stop an allergic reaction.”

THE FUTURE OF ALLERGY TREATMENT

Researchers like Sindher are still trying to understand what causes allergies, and why the prevalence of food allergies has increased over the past few decades. Sindher’s main goal is to find new ways of treating (and hopefully curing) allergies. The most established technique (for food allergies, at least) is oral immunotherapy, where allergic individuals gradually eat more of their allergen until they can have small amounts without experiencing a reaction. That’s usually done extremely gradually, over the course of months or years, and always under the supervision of a certified allergist.

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Sindher says scientists are still testing other types of immunotherapy treatments and vaccinations in clinical trials: “A lot of research is going into trying to identify the causes so we can be successful in the prevention as well as treatment of food allergies.”

Until that happens, though, doctors say the best course of action is to be careful around allergens. Medications are useful and necessary, but prevention is the name of the game when it comes to allergies.

FDA Recalls Thyroid Medications Due to Contamination Risk

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Hypothyroid medications manufactured by Westminster Pharmaceuticals have been recalled after it was discovered that one of the company’s Chinese suppliers failed to meet U.S. Food and Drug Administration (FDA) standards, CNN reports.

The oral tablets contain levothyroxine (LT4) and liothyronine (LT3), which are both synthetic hormones used to treat thyroid conditions.

The medicine was recalled as a precaution after it was discovered during a 2017 FDA inspection that the Chinese supplier in question, Sichuan Friendly Pharmaceutical Co., was not practicing good manufacturing practices.

However, patients with serious thyroid conditions shouldn’t throw out their pills just yet. No adverse effects from the medication have been reported, and the risk of not taking the medication outweighs the risk of taking a recalled pill.

According to the FDA, “Because these products may be used in the treatment of serious medical conditions, patients taking the recalled medicines should continue taking their medicine until they have a replacement product.”

For more information on the specific lots and products in question, visit the FDA’s website.

[h/t CNN]

A 'Zombie Gene' Might Be the Reason Elephants Rarely Get Cancer

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When it comes to cancer rates in the animal kingdom, elephants are an anomaly. As Popular Science notes, cancer should be more common among larger species, but with elephants, that simply isn’t the case. Only about 5 percent of elephants die from cancer, compared to 11 to 25 percent of humans.

In a new study, published in Cell Reports, University of Chicago researchers found what’s believed to be the genetic source of elephants’ cancer immunity. Elephants, like all mammals, have a gene called LIF that is known to suppress tumors. Humans have one copy of this gene, but elephants have 10 copies, which have developed over 80 million years of evolution. However, only one of those copies, called LIF6, is functional in elephants.

The other LIF copies are essentially dead because they lack a specific piece of DNA to make them function. At some point during the evolutionary process, the LIF6 gene copy turned back on, but scientists don’t know why or when this occurred. This “zombie gene” helps kill mutated cells, in true Night of the Living Dead fashion.

“This reanimation of LIF6 occurred perhaps over 59 million years,” Joshua Schiffman, who studies cancer in elephants but was not involved in the study, told Popular Science. “That’s an amazingly long period of time for nature to modify and perfect an anticancer mechanism.”

Scientists aren’t yet sure how this could be applied to cancer research in humans, but they say it’s a promising start and a creative approach to the problem. While these findings are still fresh and need to be duplicated, it raises the possibility of creating a drug that mimics the function of LIF6.

[h/t Popular Science]

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