Here’s What Happens to Your Body During Anaphylaxis

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iStock

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.

image of two epipens sitting on a desk
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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.

From Cocaine to Chloroform: 28 Old-Timey Medical Cures

YouTube
YouTube

Is your asthma acting up? Try eating only boiled carrots for a fortnight. Or smoke a cigarette. Have you got a toothache? Electrotherapy might help (and could also take care of that pesky impotence problem). When it comes to our understanding of medicine and illnesses, we’ve come a long way in the past few centuries. Still, it’s always fascinating to take a look back into the past and remember a time when cocaine was a common way to treat everything from hay fever to hemorrhoids.

In this week's all-new edition of The List Show, Mental Floss editor-in-chief Erin McCarthy is highlighting all sorts of bizarre, old-timey medical cures. You can watch the full episode below.

For more episodes like this one, be sure to subscribe here.

Game of Thrones Star Sophie Turner Opened Up About Her Struggles With Depression

Helen Sloan, HBO
Helen Sloan, HBO

Playing one of the main characters on the most popular show currently on television isn't always as glamorous as it seems. Sometimes, the pressures of fame can be too much. Sophie Turner realized this while playing Sansa Stark on Game of Thrones, and has recently revealed how being in the public eye took a toll on her mental health.

Turner took on the role of Sansa Stark in 2011, when she was just a teenager, and she quickly became a household name. Now, at 23, she's come forward to Dr. Phil on his podcast Phil in the Blanks to explain how negative comments on social media affected her self-image and mental health.

"I would just believe it. I would say, ‘Yeah, I am spotty. I am fat. I am a bad actress.' I would just believe it," Turned explained. "I would get [the costume department] to tighten my corset a lot. I just got very, very self-conscious."

Later on, these feelings led to major depression. Turner developed a sense of isolation after she realized that all of her friends and family were going off to colleege while she was pursuing a sometimes-lonely acting career.

"I had no motivation to do anything or go out. Even with my best friends, I wouldn't want to see them, I wouldn't want to go out and eat with them," Turner explained. "I just would cry and cry and cry over just getting changed and putting on clothes and be like, 'I can't do this. I can't go outside. I have nothing that I want to do.'"

The feelings of depression stayed with Turner for most of the time she was filming Game of Thrones, and it's a battle she's still fighting. "I've suffered with my depression for five or six years now. The biggest challenge for me is getting out of bed and getting out of the house. Learning to love yourself is the biggest challenge," she continued.

The actress shared that she goes to a therapist and takes medication for her depression—two things that have helped her feel better.

Between Game of Thrones ending and planning her wedding to fiancé Joe Jonas, Turner may not have the time to take on many new acting roles in the near future. However, we'll continue to see her as Sansa Stark in the final season of Game of Thrones, and as Jean Grey in Dark Phoenix, which hits theaters on June 7.

[h/t: E! News]

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