What Causes a Person to Develop Allergies?

Eric J. Schmitt, MD

Eric J. Schmitt, MD

What you'll learn in this podcast:

Dr. Eric Schmitt discusses what happens inside the body when someone has allergies, the immune system's response, and how allergies are treated.

Transcript of this podcast:

Scott Webb: You probably know that lots of people are allergic to pollens, dust, mold, and lots of other things. But did you know that some people are actually allergic to cockroaches? I didn't either. But my guest today is going to explain more about common and less common allergies and the most current cutting-edge treatment options.

And I'm joined today by Dr. Eric Schmitt. He's an allergist with Aspire Allergy and Sinus. This is Achoo!, the podcast for people with allergies and sinus issues from Aspire Allergy and Sinus. I'm Scott Webb. Doctor, thanks so much for your time today. As we get rolling here, what happens inside the body when a person has allergies?

Dr. Eric Schmitt: So the most classic allergic reaction is defined by IgE or immunoglobulin E where you'll have a specific allergic antibody that regards an allergen when you're exposed to it. So this functions very much like a lock and key mechanism. So you have a very individualized IgE against a specific allergen and the reaction that occurs then, very simply, once the loc kfinds the right key is this complex of allergen bound to allergic antibody does bind to cells in the body, namely, mast cells and the IgE receptor on the mast cells then become activated. And in the activation of the mast cells leads to histamine release. And once histamine is released, that leads to our classic allergic symptoms, namely itching, hives, redness, swelling, mucus production, which can happen in the respiratory tract and the nasal passage or in the airways.

Scott Webb: Yeah, and I think we're all familiar with those symptoms, unfortunately, whether we have seasonal allergies or other things that we're allergic to. And I want to have you kind of talk about the body's immune system. We think about an allergen as this sort of invader, if you will, right? So maybe you can just kind of go over the concept of the body's immune system and how it reacts exactly to these invaders.

Dr. Eric Schmitt: Yeah. I think looking at an allergen as an invader is a very interesting kind of concept for patients to embrace. And one of the questions that comes up is, you know, what's the purpose of having allergies? And it is a reaction to, say, that your body is wanting to have some form of a defense against this invader.

Now, why we've selected common food allergens or common airborne allergens as an invader is a slightly different discussion. But basically what our body is telling us is "We don't want this to get in." So we start having this response from the allergic immune system and some of the symptoms that you can get, particularly, from food allergens will be pretty dramatic where you can get throat closing and tightening and your bronchospasm where your airways closing off and, of course, vomiting. So these are things that are symptoms and signs of having kind of an allergy, but it's a form of a defense of your body saying, "Look, I don't want to get this deeper inside me."

Airborne allergens is really very similar concept in that it's typically the respiratory tract or nasal passage gets very stuffy, gets very closed off when we start, you know, breathing the allergens in through the nasal passage. And similarly for the patients who are dealing with asthma, they'll have a very early phase allergic response when they're exposed to those airborne allergens they are sensitive to, they'll have fairly immediate bronchospasm.

Scott Webb: Yeah. And we were speaking before we got rolling here. So I have some kids in school and I remember being in school and I don't remember kids having the allergies that they have now, like I never heard of a peanut allergy, you know, when I was a kid and maybe people just weren't allergic to peanuts or we just didn't talk about it and there wasn't access to the information that we have today. So I think my question really is when do people really develop allergies, food or otherwise? Is that earlier in life for some types of allergies and then later in life for others? Maybe you can take us through this.

Dr. Eric Schmitt: So an easy way to answer that is it can be anytime, but it's much more common to be in early childhood or through, you know, young adulthood and depending on the type of allergies. Clearly, I agree with you. We did not see generations ago nearly as much allergy and there's potentially some explanations for that.

It's thought to be generally a defect or a lack of developing proper tolerance to these allergens when we're first being exposed to them. So the timing for the allergies is our body gets exposed, whether it's these airborne allergens or food allergies. And since we do not develop a tolerance, because our immune system hasn't necessarily learned to accept this as something that we should form allergies to, the allergic response then begins to develop. So it's essentially a lack of tolerance.

And one of the things that has changed over the years is instead of trying to minimize and avoid allergies by following exclusive restriction and lack of introduction of, for example, food allergens early in infancy is we're embracing a concept now of actually introducing those concerning food allergens at a much earlier age while our body is basically making the choice of selecting whether these allergens will become something do we become tolerant to versus something that we'll become intolerant and allergic to.

Scott Webb: That's really interesting the way you put that. And if we had more time, maybe a different podcast, we could kind of talk about that, that, you know, maybe we got where we are, let's say with peanut allergies or food allergens, because parents were avoiding introducing, you know, those things to their babies earlier. And now it seems like the trend's going back the other way. And as you say, the body makes a choice, the body sort of decides, "I'm going to be allergic to this, but I'm not going to be allergic to that." It's really interesting, isn't it?

Dr. Eric Schmitt: It's a very interesting concept and it's not so much the family making a choice. For decades, physicians, pediatricians, etcetera, have been advising parents to do this. But when more data comes around that it becomes clear that perhaps one of the reasons we were going in the wrong direction was this lack of early introduction. And it seems to become clear over the last few years that early introduction of concerning food allergens is very beneficial to reduce the risk of developing a lifetime of allergies to those foods.

Scott Webb: Yeah. And that's the goal, right? Even if a child has allergens or, you know, when they're younger or little, we kind of want them not to be allergic to things for the rest of their lives if we can avoid that. So sort of prompts the follow up question, do people, can people really grow out of -- I'm using air quotes -- can they grow out of allergies?

Dr. Eric Schmitt: Food allergies, for example, that we see in very early infancy and there were some that are not necessarily IgE-mediated. These are classic milk protein allergies, where an infant may have colic or some bloody stools. And those we don't regard as allergies that we would expect to be permanent allergies. But even with that said, there are plenty of children that develop food allergies during infancy. They'll have, for example, atopic dermatitis, which is a skin allergy, eczema, where the allergic exposure is leading to chronic rashes. And of course the, risk for anaphylaxis from these foods and yet, milk and eggs are classic food allergens that while it's very common seen in children under two years of age, we do expect most of those children to outgrow that allergy and not have an anaphylaxis risk. Defining probably by age around eight to ten or so, most of those children are outgrowing those allergies.

Adults, similarly, whether it's food or environmental allergies, they will be sensitive at times to animals, dust, different pollens. They move to different regions and they will seem to not be as significantly affected by those allergies. So I do think there is a concept that people are able to "grow out of their allergies" as you like to say. But the problem we face with this is we're not sure what those changes are that people are doing as to what will help them grow out of their allergies with the exception of what we can do medically, which is offering, you know, forms of allergen immunotherapy.

Scott Webb: Yeah, I'm sure a lot of it is anecdotal and hard to exactly pinpoint. Well, I was allergic to this thing before, and now it doesn't appear that I am, but as you say, there could be so many factors simply moving, you know, to a different climate or something like that. And, you know, you mentioned pollens and so those are sort of the common hit-list there, pollens, dust, mold. And in doing a little research for this, I also found that people can be allergic to cockroaches, which, you know, cockroaches are gross, but I didn't know people could actually be allergic to them. So let's talk about that. Which allergies are most common for folks?

Dr. Eric Schmitt: Yeah. So just highlighting cockroach allergen for a minute. A cockroach allergen is a very much an inner city allergy problem. Perennial allergens when you're a child, you're more apt to develop the allergic sensitivities a little bit sooner. You're around these allergens all the time, dust, potentially pets if you're living with them and of course cockroaches, if that's something that's part of your home environment. And children who are exposed to the cockroach allergen who develop cockroach allergic sensitivities much have a higher likelihood of developing early-onset asthma and asthma that can then persist a little bit later in life, particularly if they also become, you know, mold, dust and cat and dog allergic.

Pollen allergies, of course, your trees, grasses, and weeds are what we see a little bit more as we get older, because we've needed a bunch of seasons for our immune systems to got exposed to these allergens to become educated in the wrong way, if you will, where they develop the sensitization and then have the learning when another season rolls around, that we start mounting a greater allergic and immune response, and we start developing more symptoms through the years. So we'll see pollen allergies being a little bit more common in older childhood and of course in adults.

Scott Webb: Yeah, this is just so good to go through, I don't know that everybody is allergic to at least something, but certainly there are things that probably irritate all of us to one degree or another, whether it's seasonal or food or whatever it might be. So really great to speak with you today.

And as we wrap up here, let's talk about how you treat allergies because, you know, I know that antihistamines work, but it's not really a long-term solution. And I know immunotherapy sounds like something out of science fiction, like out of Star Trek. I'd like to have you go through that. Let's talk about how we're treating allergies today and maybe, you know, what's in store for the future.

Dr. Eric Schmitt: Yeah. So medication treatments do control symptoms of allergies, but they don't necessarily provide any additional relief for patients as far as making sure that they're not going to be subsequently allergic. And the antihistamines, nasal sprays, they do work well in the short-term, but long-term. There's really no answer for that.

So doctors, allergists, for years have developed different forms of immunotherapy. There is injection or subcutaneous immunotherapy. Allergy shots is the more colloquial term for that, where patients are getting exposed through subcutaneous injections of what they're sensitive to from these airborne environmental allergens. Again, the pollens, dust, pets, mold, et cetera. And then over time, there's changes in the body with this therapy on your immune system, where your immune system is now becoming less reactive and we're somewhat correcting mostly the concept more like as a vaccine, where through an exposure to the vaccine, our bodies now mount a different immune response, so that when we get exposed airborne-wise to these allergens, they're not leading to a sickness or illness as much.

More recently, there is a form of immunotherapy allergy drops or what we call sublingual immunotherapy. Sublingual stands for under the tongue and the drops are held under the tongue for airborne allergens. And that also seems to provide an entry into the body where the body will receive these allergens and make a better immune response and a less allergic immune response overtime.

These drops and forms of actually oral immunotherapy are newly helpful for food allergies and patients who live with life-threatening anaphylactic reactions to their food allergens have an option now of pursuing either through these allergy drops or what's considered OIT or oral immunotherapy, where they can become less reactive to potentially an inadvertent exposure and even progress to the point where they can start to reintroduce foods into their diets and be able to freely eat the food allergens that they've had to restrict from their diets so definitively for years.

Scott Webb: Well, it sounds like there's every reason for folks with allergies who suffer from these different variety of allergens that we've discussed today, every reason for them to be optimistic. A lot of really cool stuff happening. And just the thought of folks who've been avoiding these foods, you know, for decades being able to come back and have that whatever, peanut butter and jelly sandwich, whatever it might be, brings a smile to my face. So this has been really educational today, doctor. Thanks so much. Stay well.

Dr. Eric Schmitt: Well, very good. Thank you.

Scott Webb: That's Dr. Eric Schmitt, allergist with Aspire Allergy and Sinus. Find more episodes and information at aspireallergy.com/podcast. This has been Achoo!, the podcast for people with allergies and sinus issues from Aspire Allergy and Sinus. I'm Scott Webb. Stay well.

About this provider

Dr. Eric J. Schmitt graduated with honors in Biomedical Engineering from the University of California, San Diego. He earned his medical degree from Tufts University School of Medicine before completing Pediatric Residency training at Washington University of St. Louis and Brown University. Dr. Schmitt completed his Allergy / Immunology fellowship training at the University of Texas Southwestern Medical Center in Dallas.

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