Episode transcript
Time stamps
0:30 - Introduction of today’s episode.
1:02 - Allergen component resolved diagnostics overview.
6:18 – How can pet allergen component testing optimize patient management?
9:34 – A deeper dive into specific pet allergen component.
13:15 – Fel d 1 & Can f 5 pet allergen components.
18:15 – How to order pet allergen components through your lab.
Announcer:
ImmunoCAST is brought to you by Thermo Fisher Scientific, creators of ImmunoCAP™ Specific IgE Diagnostics and Phadia™ Laboratory Systems.
Gary Falcetano:
I'm Gary Falcetano, a licensed PA with over 11 years experience in allergy and immunology.
Luke Lemons:
And I'm Luke Lemons with over five years of experience writing for healthcare providers and educating on allergies. You're listening to ImmunoCAST, your source for medically and scientifically-backed allergy insights. Welcome. Today on ImmunoCAST we're going to be talking about a cutting-edge type of allergy diagnostics. There're many clinicians across the country who are already using, but some may have not heard of or don't have any experience with. And before I tell you the name, I'm going to tease it a little more. So this cutting-edge allergy diagnostics, it can provide insight into whether a patient can tolerate baked or lightly cooked eggs, male or female dogs, or potentially even predict disease severity for patients with pet allergies for that matter and a whole lot more. And what I'm talking about today is allergen component-resolved diagnostics. And we're going to be talking about-
Gary Falcetano:
A mouthful.
Luke Lemons:
Oh yeah, it's a big mouthful. And we're going to be talking about pet allergen component diagnostics specifically.
Gary Falcetano:
Yeah. And so the other term for this is called molecular allergology, which is another mouthful. But as you mentioned, today we're going to be focusing in on just one part of this allergen component testing, and that's for pet allergen components. It's really exciting because this is really the first widely available allergen component testing that's available for respiratory symptoms. We've had food allergy components for quite a while now. We have components for some other allergy-mediated disorders, but these are the first widely available in the US components for respiratory disease, specifically rhinitis and asthma. All of the typical allergic respiratory diseases or potentially allergic respiratory diseases that we discuss and see on a regular basis.
The interesting thing about these is that they provide a lot of additional in-depth information around pet selection, around disease development and severity, as well as being able to guide us to have better exposure reduction strategies and even guide appropriate specialist referrals.
Luke Lemons:
And for all those reasons, that's why Gary and I want to talk about pet allergen components today, which is a blood test. But before we get into specifically pet allergy components, let's back up a little bit for some of our listeners who may be unfamiliar with allergen components as a whole.
Gary Falcetano:
Yeah, absolutely. I think a lot of our listeners will have used allergen components of some type in the past, but I do think we may have some users who aren't. So I guess probably the best way to start thinking about allergen components is really with an analogy or two. And I'm going to throw this out there. How about these two analogies, cholesterol and beef stew?
Luke Lemons:
It sounds like a hearty meal in the wintertime. Some stew has cholesterol, but I don't know if I'd want just pure cholesterol or my stew.
Gary Falcetano:
Well, and we know that stew may not be the best thing to eat for our cholesterol. So when we think about cholesterol, we know that before the 1960s we had the ability to measure total cholesterol. And while that was informative, it really didn't give us any really risk stratification for potential cardiovascular disease, for atherosclerosis. So after the '60s, we were able to identify and then fractionate out the HDLs, the LDLs, triglycerides, and really clinicians were then better able to understand cardiovascular risk. So just like with cholesterol and these HDL and LDL components, whole allergens and their individual allergen components provide us with additional diagnostic insights to really help with not only diagnosis but also management.
Luke Lemons:
And so what you're saying is HDL and LDL is to cholesterol as allergen components is to whole allergen.
Gary Falcetano:
You're always able to just clarify my many words in a very concise statement. So that's absolutely correct.
Luke Lemons:
So what does this have to do with stew? What's the analogy there?
Gary Falcetano:
So it's just another way to visualize it. So whole allergens if we think about them like a stew, that are made up of many different molecules which are mostly proteins to which patients can be sensitized and or allergic to. So when someone is sensitized to a whole allergen, we're not sure what in that stew is actually causing the sensitization. So allergen components are perhaps the potatoes or the carrots in that stew. And knowing that someone is sensitized to just one or more of those components can really help us look at their individual sensitization profile and better predict how they're going to express disease, and how that disease is actually going to affect them.
Luke Lemons:
So with most diagnostic allergy tests, we look at the whole allergen, the stew. And this is because generally it offers a greater sensitivity, but then the allergy components, the carrots and the potatoes, they increase specificity when looking at an allergy creating this next level of precision medicine. Is that fair to say?
Gary Falcetano:
Yeah. And I think when we're looking at them, they really still need to be used together. We're not replacing the whole extract allergens, we're using the allergen components in a complementary manner with the whole allergen. So getting as you said, Luke, the sensitivity provided by the whole allergens and then adding additional specificity and information provided by the components.
Luke Lemons:
So looking at pet allergen components specifically, what is the impact of them being incorporated into a practice? How can they help primary care providers or providers as a whole?
Gary Falcetano:
Yeah, so there's multiple benefits from assessing the pet allergen components. I think one of the most interesting ones is the ability to predict the development of disease. So we've seen studies that showed that children who are sensitized to three or more pet components, dog or cat, or both at age four are more likely to demonstrate clinical respiratory disease at age 16. So if someone is sensitized to three or more components, again at age four, they have an 80 to 90% chance of actually having respiratory disease, whether that be rhinitis, asthma, or even rhinoconjunctivitis at age 16.
Luke Lemons:
And so how can allergen components help assess severity in adults or outside of that even?
Gary Falcetano:
Yeah, so we see the development of disease in children. But in both adults and children, the number of components or pet allergen components that you're sensitized to at any age can be related to disease severity. So it can actually help you kind of phenotype patients on just how severe their disease actually is based upon the number of pet components they're sensitized to.
Luke Lemons:
And this can help with referrals after the fact as well. And immunotherapy if you are to refer to an allergist, understanding which patients are at a high risk and need to undergo that treatment, right?
Gary Falcetano:
Exactly. And it can also be used to help get patients' buy-in, to be more adherent to recommendations. So if someone is at a very low risk based upon a small number of allergen components that are positive versus a patient who's at high risk, they have multiple components that are positive, we're able to really objectively demonstrate that, "Listen, you need to really take this seriously." Perhaps again, being referred to an allergist for immunotherapy, perhaps even taking the most extreme measures which we try not to do of even re-homing a pet. And so while these components can really help us do target exposure reduction, hopefully reduce their symptoms without re-homing a pet, it may be that if they're at such severe risk that may have to be an option to be considered.
Luke Lemons:
I'm glad you touched on the re-homing a pet thing, because it must be so hard to have a conversation with a patient who has a pet allergy and that's the only solution that you can see going forward to help with guidance. Because if you're just testing with a whole allergen and you're allergic to dog, you don't know the severity of how allergic that patient is. Is them sacrificing their family member going to make an impact? Because if they have to re-home and they're still experiencing symptoms, that's a tough conversation to have after the fact.
Gary Falcetano:
It is, absolutely. And I think it is kind of the last resort. So there are a lot of other things that we recommend that you can do before getting to that last resort. But it is a difficult conversation, it's having as much objective evidence as you can to support that recommendation I think is really important if you eventually get there.
Luke Lemons:
I know we've been mentioning components as this kind of catch-all term, components and molecules. And you're probably wondering as a listener, well, what are these components, what are their names? And allergen component resolve diagnostics, they also have confusing names. So Gary, I'll let you kind of explain why we name these components certain things, and some examples of these components.
Gary Falcetano:
Yeah. And luckily for our listeners, there are plenty of resources, interpretation guides and we'll talk about those in a minute, that really detail what the components are, what their names are, what their meanings are. But in general, they're named from the Latin name for the species. So with cats it's Felis domesticus or Fel d. So the first three letters of the genus, first letter of the species and then a number. So which do we talk about cat components like Fel d 1, Fel d 2, Fel d 4. We talk about dog components and here it's named after, again, the Latin name for dog is Canis familiaris, which is the Latin name for domesticated dogs. And it's Can F one, two, five, et cetera. Before we talk about though the individual components like that, I do want to talk about how the overall pet components can be used for pet selection.
So take a guess, Luke, if I'm sensitized to cat, so I think I have a cat allergy, I may have a dog allergy, I'm not sure. We do whole extract testing, what percentage of patients do you think that are sensitized to one species like cat would also be sensitized to dog?
Luke Lemons:
Cats and dogs, I'm trying to think. Cats and dogs are very different.
Gary Falcetano:
They are.
Luke Lemons:
Yeah, they are, I would say 90%.
Gary Falcetano:
Well, they're a little bit more different than that. We see about 73% of patients that are sensitized to one or the other are also sensitized to the opposite. So about three-quarters of patients are sensitized, meaning they have positive whole extract tests to both cat and dog. But they're not all, all of those patients are not allergic. We've talked about many times in the past with this podcast that sensitization does not always equal clinical allergy, expression of symptoms. And this is another spot where pet allergen components can really help tease out are these irrelevant cross-reactivities that are causing both whole extracts to be positive, or are these relevant proteins that are actually associated with true clinical disease coming from that pet.
Luke Lemons:
So you said 73% of patients that are sensitized to dog or cat are sensitized to both? No. Yeah, I don't know. I threw out 90. 73 makes more sense but that's still very shocking because you would assume that it would be lower, I don't know, in my mind.
Gary Falcetano:
Exactly. And like I said, sometimes these are relevant. They are allergic, they will end up being allergic to both but sometimes it's not. And the components themselves can help us figure out because we have what we call species specific of allergen components, that are only found in a cat or a dog. And if those are positive, then they kind of confirm along with symptoms that the patient has a cat or a dog allergy or both.
Luke Lemons:
And I know a little bit about the individual allergen components across food, pets, stinging insects, et cetera. But looking at pets, Gary, why don't we both talk about our favorite allergen components?
Gary Falcetano:
Yeah, why don't you go first? What's your favorite, Luke?
Luke Lemons:
I think that Fel d 1 is so interesting. So that's a cat allergen component. And it's interesting, it is a major cat allergen component. It's found mostly in the skin and in the saliva of the cat. And this is what's so cool about it in my mind, is that because it's found in the saliva there are specific products, anti-Fel d 1 one products that can disable that allergen component found in cat saliva. So for example, Purina has a cat food out there that if people feed their cats this cat food, it actually disables the Fel d 1 allergen component in-
Gary Falcetano:
Yeah, exactly. I think the word there is actually bind it, but it really does infact disable it.
Luke Lemons:
Yeah, binding. And I just think it's so interesting that somebody could have a cat allergy, and all they would need to do would be to feed their cat this food and that allergen component doesn't affect them as much. It's not getting rid of the Fel d 1, but it's just making it so it's not affecting that patient. I think that that's super interesting. What's yours, Gary?
Gary Falcetano:
So I would say Can f 5, so this is the dog component. Can f 5 is produced in the male dog's prostate. Hopefully we don't have a female dog with a prostate. So it's only produced in male dogs. And the interesting thing about this is we often see patients who are mono-sensitized to Can f 5. So what that means is they don't have any of the other dog allergen components positive, only Can f 5. As a matter of fact, we've seen studies in as much as 58% of patients are mono-sensitized. So what does that mean? They can potentially tolerate a female dog, which I think is really pretty cool.
Luke Lemons:
Yeah, that's really interesting. This was probably a close second for me too because Can f 5, the fact alone that a patient may be able to tolerate a female dog if this is the only allergen component that they're sensitized to, that's interesting. But also, and we may talk about this on an allergy after dark episode, so we won't get too deep into it. But there's some cross-reactivity with Can f 5, right, Gary?
Gary Falcetano:
Yeah, there is. And so with a lot of these components, as I said, some are cross-reactive, some are species-specific. We know that there are several things like serum albumins that are cross-reactive between horses even, cats and dogs that can cause positivity among all three species. But Can f 5 doesn't have another cross-reactive counterpart in any of the other animal species except one. And I know you know what this is, Luke. So you want to tell our listeners where we see an amino acid sequence identity that's similar to the Can f 5 in the dog.
Luke Lemons:
Yeah, so we see it in humans. And the equivalent is found actually in PSA. And it has been associated in several papers with human semen allergies. Meaning if a woman who has a Can f 5 only sensitization allergy, they may react to their male partner's semen because of this clinical cross-reactivity.
Gary Falcetano:
Yeah. And it's been fairly conclusively demonstrated in several studies. And I think, again, we'll talk about this more in another after dark episode. But I think this may even have potential implications in fertility treatment. We'll have to see. We need a lot more studies on the subject.
Luke Lemons:
Yeah, but looking at these individual proteins that Gary and I just mentioned, Fel d 1, Can f 5, the power of knowing if a patient is allergic to just that protein it's incredible when it comes to patient management, because if you're just testing for a whole cat allergen it's going to come back elevated. But what if it was only Fel d 1 that they were reacting to or that they're sensitized to in that stew of the whole allergen? So knowledge as always is power.
Gary Falcetano:
Exactly. And you mentioned that cat food. So we know there's this anti-Fel d 1 cat food. If you're not sensitized to Fel d 1, you're kind of wasting your money buying an anti-Fel d 1 cat food. So knowing exactly what those sensitization profiles are can be very beneficial.
Luke Lemons:
And this is the clinical value. And so Gary, when a patient comes in and is asking if they can have a dog or cat or if they're just like, oh, I'm allergic to dogs in general, how would you approach them with maybe wanting to test with allergen components?
Gary Falcetano:
Yeah, so even before allergen components, we know that a lot of these diagnoses get made based upon history alone. And we've talked about in previous podcasts on how imprecise that can be. So we know when it comes to dogs and cats, using history alone without any laboratory testing ends up with a lot of false positives. About 30% of the time on average for dogs and cats, we blame them and they're not actually the cause of symptoms. So testing in general is very important to correlate with the history and symptoms to get to the diagnosis. And then using the allergen components or the pet allergen components to take an even deeper dive like we've been talking about, is really just part of that diagnostic process.
Luke Lemons:
And what's nice is that pet allergen components being a respiratory allergy test, they're found in respiratory allergy profiles when doing specific IgE blood testing. And they often in these profiles reflex. So if you do test a patient using a respiratory profile with pet components and reflexes, if the patient comes back with elevated levels of dog allergen sensitivity, it will immediately reflex and then test those allergen components, which saves again so much time in diagnostic testing to get those patients the information that they need and to help you better manage.
Gary Falcetano:
And it's also efficient, because we're not going to test those components if they're not positive to the whole extract. So we're not getting unnecessary testing either.
Luke Lemons:
And if you go to this episode's page at thermofisher.com/immunocast, we'll have a link to a lab ordering guide with that respiratory allergen profiles for a bunch of labs that you may use already. So we made sure to include those that have the reflexes in there to again save on efficiency
Gary Falcetano:
Yeah. And Luke, it's just an improved respiratory allergen profile. We really should be moving to, if you're using respiratory profiles you should be using respiratory profiles with pet reflex because it really is the next evolution of the testing.
Luke Lemons:
100% agree, Gary. And we'll also include on this episode's specific page, pet allergen component compendium, which is this mouthful of words today. Compendium that has all the information on pathogen components. And if you want to take a deeper dive, we will also have on this episode's page an interpretation guide for pet allergen components that Gary had mentioned earlier, that explains a little more about these specific components, the molecules and how they may affect one another and how they may affect your patients.
Gary Falcetano:
Yeah, and these resources make it very easy to not only know what the results are that you're getting back, but be able to provide actionable information to patients to really improve their symptoms and their lives.
Luke Lemons:
So thank you for listening today. We learned a lot. I learned that Gary is a dog guy and I'm a cat guy based off of our favorite allergen components, that's the litmus test. Maybe I'll start saying that when people ask if I'm a dog or cat person. I'm a Fel d 1 one person. But thank you for listening-
Gary Falcetano:
Can f 5 right here.
Luke Lemons:
Yeah, Can f 5. Thanks for listening to ImmunoCAST. We hope you enjoyed the episode. And don't forget to visit thermofisher.com/immunocast. And be sure to share this episode with your fellow providers or even patients. And follow for more allergy insights for medical minds.
Gary Falcetano:
Thanks so much. We'll see you next time.
Luke Lemons:
Bye everyone.
Announcer:
ImmunoCAST is brought to you by Thermo Fisher Scientific, creators of ImmunoCAP™ Specifc IgE diagnostics and Phadia™ Laboratory Systems. For more information on allergies and specific IgE testing, please visit thermofisher.com/immunocast. Specific IgE testing is an aid to healthcare providers in the diagnosis of allergy and cannot alone diagnose a clinical allergy. Clinical history alongside specific IgE testing is needed to diagnose a clinical allergy. The content of this podcast is not intended to be and should not be interpreted as or substitute, professional medical advice, diagnosis or treatment. Any medical questions pertaining to one's own health should be discussed with a healthcare provider.
