# What is an Allergen? **URL:** \ **Category:** Factual Questions\ **Created:** [September 25, 2013, 4:42pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656 "2013-09-25T16:42:46Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![Knorf](https://avatars.discourse-cdn.com/v4/letter/k/58956e/32.png) [@Knorf](https://boards.straightdope.com/u/Knorf)\ **Post date:** [September 27, 2013, 8:23pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/21 "2013-09-27T20:23:00Z")
I stand semi-corrected. Sulfites! Get with the times, people! ---
**Author:** ![Mgalindo13](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@Mgalindo13](https://boards.straightdope.com/u/Mgalindo13)\ **Post date:** [September 27, 2013, 8:51pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/22 "2013-09-27T20:51:21Z")
> [@Mangetout](#): > > Right, but please could you explain why you said: > > When the middle\* of those three links doesn’t actually seem (to me) to be saying any such thing. > > \*Actually, I can’t really see how you’re getting it from the first one either. > > And the last one is just a link to a book for sale on Amazon - Are you referring to a specific statement made in that book? (Do you own a copy?) From the first link: “A nonparasitic antigen capable of stimulating a type I hypersensitivity reaction in atopic individuals is called an allergen.” From the second link: “the term ‘allergy’ is increasingly being confined to denote type I hypersensitivity reactions” **AND** “allergy is defined as a condition triggered by a specific, acquired immune response to a harmless, non-pathogenic **antigen**.” The last I referred to upthread, it’s “the term allergen refers specifically to nonparasitic antigens capable of stimulating type one hypersensitive responses in allergic individuals.” You can review it by using Google books [here](http://books.google.com/books?id=8281_jkbdhoC&lpg=PA363&ots=Pu6W88fVuw&dq=term%20allergen%20refers%20specifically%20to%20nonparasitic%20antigens&pg=PA363#v=onepage&q=term%20allergen%20refers%20specifically%20to%20nonparasitic%20antigens&f=false). ---
**Author:** ![Mgalindo13](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@Mgalindo13](https://boards.straightdope.com/u/Mgalindo13)\ **Post date:** [September 27, 2013, 9:12pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/23 "2013-09-27T21:12:02Z")
> [@DSeid](#): > > Most of what I read does not limit “allergy” to Type I Hypersensitivity Depends on here you look for the definition. According to [Websters](http://www.merriam-webster.com/dictionary/allergy) an allergy is defined as “a medical condition that causes someone to become sick after eating, touching, or breathing something that is harmless to most people.” Using this definition, lactose would be considered an allergen. Obviously that’s not the case. Using medical (specifically immunological) textbooks we see a more narrowly defined term as I have posted previously. > [@DSeid](#): > > but even accepting that definition it is still true that there are mechanisms by which a non-protein substance can provoke an allergic response. A hapten binding to a self protein which then triggers an allergic cascade is still the non-protein provoking the response. My original contention was that a protein is required to generate a true allergic response. Haptens still fit this category as the must be bound to the protein. No protein, no response. > [@DSeid](#): > > Tobacco smoke provoking TH2 responses and by way of functioning as an extremely effective adjuvant allowing an allergic reaction to occur is still its provoking the allergic response. Moreover, whether or not an IgE response to the proteins in tobacco smoke has been ever documented is immaterial to the statement that such “can” occur. I don’t think it’s correct to say that because something is theoretically in the realm of possibility that it positively exists. > [@DSeid](#): > > Finally such have been documented. [MJH Life Sciences® | Transforming Care from Discovery to Delivery™](http://www.modernmedicine.com/modern-medicine/news/modernmedicine/welcome-modernmedicine/tobacco-may-trigger-specific-allergic-i-0) Your cite discusses the presence of a tobacco allergy, specifically to the pollen of the plant. There is no evidence (that I can find) that this pollen would survive the manufacturing process of the tobacco into a cigarette or incineration during the process of smoking. Again, I understand you point and stipulate that it’s _possible_, but there’s still no data proven to show it’s true. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 27, 2013, 9:56pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/24 "2013-09-27T21:56:52Z")
> [@Knorf](#): > > I stand semi-corrected. Sulfites! Get with the times, people! I’m English and have always spelt it with the ‘ph’. I’ll switch to spelling it with an F when America goes metric, deal? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 27, 2013, 10:07pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/25 "2013-09-27T22:07:54Z")
> [@Mgalindo13](#): > > My original contention was that a protein is required to generate a true allergic response. Haptens still fit this category as the must be bound to the protein. No protein, no response. That wasn’t exactly your original contention. Your original contention was that the root cause itself had to contain a protein: [QUOTE=Mgalindo] You may want to avoid using that excuse considering cigarette smoke can’t actually cause an allergic reaction as it lacks any protein to cause an immune system response. [/quote] ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 27, 2013, 10:13pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/26 "2013-09-27T22:13:48Z")
> [@Mgalindo13](#): > > From the second link: “the term ‘allergy’ is increasingly being confined to denote type I hypersensitivity reactions” How is this a refutation of anything? The SO2 allergy in question is being described as type I hypersensitivity. ---
**Author:** ![Mgalindo13](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@Mgalindo13](https://boards.straightdope.com/u/Mgalindo13)\ **Post date:** [September 27, 2013, 10:45pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/27 "2013-09-27T22:45:42Z")
> [@Mangetout](#): > > That wasn’t exactly your original contention. Your original contention was that the root cause itself had to contain a protein: How is that different? A protein is required to cause a reaction. Attached to a hapten or not, a protein is still required. It’s congruent with my original statement. > [@Mangetout](#): > > How is this a refutation of anything? > > The SO2 allergy in question is being described as type I hypersensitivity. Did you see the second part I quoted from the same article? “Allergy is defined as a condition triggered by a specific, acquired immune response to a harmless, non-pathogenic **antigen**.” The type one sensitivity to sulfites is still the issue in contention. Thus far the only evidence you’ve supplied is a PDF fact sheet without any references to any medical studies or reports. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 27, 2013, 11:15pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/28 "2013-09-27T23:15:19Z")
> [@Mgalindo13](#): > > How is that different? A protein is required to cause a reaction. Attached to a hapten or not, a protein is still required. It’s congruent with my original statement. You’ve moved the goalposts here. Your assertion was to the effect that the protein would have to be contributed by the smoke. > [@](#): > > Did you see the second part I quoted from the same article? “Allergy is defined as a condition triggered by a specific, acquired immune response to a harmless, non-pathogenic **antigen**.” Yes, and I have to say, what you did there looks like something called Quote Mining - selectively quoting incomplete sentences from a passage to make it better fit your argument. Let’s take a look at the whole definition preamble from your link (your selection is graped - an important bit you omitted is in red): > [@](#): > > Allergy > What is an IgE-mediated allergy? > Allergy is classically defined as an exaggerated, pathological, specific immunologic reaction to foreign (exogenous) substances. > > As the body of evidence in immunology and immunopathology grows, the term ‘allergy’ is increasingly being confined to denote type I hypersensitivity reactions. However, there is as yet no consensus about definitions. In a somewhat narrower sense, allergy is defined as a condition triggered by a specific, acquired immune response to a harmless, non-pathogenic antigen. > [@](#): > > The type one sensitivity to sulfites is still the issue in contention. Thus far the only evidence you’ve supplied is a PDF fact sheet without any references to any medical studies or reports. And the citation provided by **DSeid**. But frankly, I’m not hopeful you would accept the content of an in-depth report even if I did have access to one. ---
**Author:** ![Mgalindo13](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@Mgalindo13](https://boards.straightdope.com/u/Mgalindo13)\ **Post date:** [September 27, 2013, 11:40pm UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/29 "2013-09-27T23:40:47Z")
> [@Mangetout](#): > > You’ve moved the goalposts here. Your assertion was to the effect that the protein would have to be contributed by the smoke. And it would. A protein would still have to be present. Again, how is that different? > [@Mangetout](#): > > Yes, and I have to say, what you did there looks like something called Quote Mining - selectively quoting incomplete sentences from a passage to make it better fit your argument. Let’s take a look at the whole definition preamble from your link (your selection is graped - an important bit you omitted is in red): If I was quote mining I wouldn’t have selected that cite. I can provide a dozen others that supply the same definition. I cropped for ease of reading. Meanwhile you’re still ignoring my other two cites. > [@Mangetout](#): > > And the citation provided by **DSeid**. Nowhere in his cite does it state that sulfites produce an IgE response. Unless I missed something, please feel free to point it out if I did. > [@Mangetout](#): > > But frankly, I’m not hopeful you would accept the content of an in-depth report even if I did have access to one. You’re certainly welcome to provide one and find out. Neither you or DSeid have provided a reliable cite that an IgE response can be derived from a sulfite. We’re really not getting anywhere. I have provided multiple cites with clear cut definitions of what an allergen is (in the medical community) and you appear to be purposely obtuse. You ignore my cites that don’t support your position and attempt to attack my credibility based on editing for ease of reading. And still you have provided nothing of substance to this conversation. Not one study, university research paper or medical journal article. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 28, 2013, 12:01am UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/30 "2013-09-28T00:01:56Z")
> [@Mgalindo13](#): > > And it would. A protein would still have to be present. Again, how is that different? A protein would not have to be present _ **in the smoke itself** _. > [@](#): > > If I was quote mining I wouldn’t have selected that cite. I can provide a dozen others that supply the same definition. I cropped for ease of reading. Meanwhile you’re still ignoring my other two cites. OK, from the first one (bolding mine): > [@](#): > > Allergen > > An allergen is **any substance** (antigen), most often eaten or inhaled, that is recognized by the immune system and causes an allergic reaction. > > Dust, pollen and pet dander are all common allergens, **but it is possible to be allergic to anything.** and > [@](#): > > In atopic individuals, non-parasitic antigens stimulate inappropriate IgE production, leading to type I hypersensitivity. > > A nonparasitic antigen capable of stimulating a type I hypersensitivity reaction in atopic individuals is called an allergen. Sensitivities vary from one person to another and it is possible to be allergic to an extraordinary range of substances. Dust, pollen and pet dander are all common allergens, but it is possible to be allergic to anything from chlorine to perfume\*\*\*\* > [@](#): > > Nowhere in his cite does it state that sulfites produce an IgE response. Unless I missed something, please feel free to point it out if I did. Of course, we only have the abstract, which yes, does not include that specific terminology, however, it does mention life-threatening anaphylaxis, which in most cases is an immune response. > [@](#): > > We’re really not getting anywhere. I have provided multiple cites with clear cut definitions of what an allergen is (in the medical community) and you appear to be purposely obtuse. You ignore my cites that don’t support your position and attempt to attack my credibility based on editing for ease of reading. And still you have provided nothing of substance to this conversation. Not one study, university research paper or medical journal article. You’ve done quite enough to undermine your own credibility on your own. Including the fiasco of selective misreading in the other thread that you never properly acknowledged either. Pot. Kettle. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 28, 2013, 12:28am UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/31 "2013-09-28T00:28:19Z")
Here is a detailed case report of allergic reaction to metabisulphite (including positive skin tests): > **[Allergic response to metabisulfite in lidocaine anesthetic solution.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2007334/?page=1)** > > True allergies to local anesthetics are rare. It is common for practitioners to misdiagnose a serious adverse event to local anesthetics as an allergic reaction. The most likely causes for an allergic response are the preservative, antioxidant, or... Here is a discussion of adverse reactions to sulphites (which acknowledges that the mechanism is not known, but states positive skin test evidence and states that this suggests an immune response): > **[Adverse reactions to sulfites](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1346296/?page=1)** > > Sulfites are widely used as preservatives in the food and pharmaceutical > industries. In the United States more than 250 cases of sulfite-related adverse > reactions, including anaphylactic shock, ... ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [September 28, 2013, 12:49am UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/32 "2013-09-28T00:49:52Z")
Protein is involved somewhere in the allergy response. Yes, that is always true since immunoglobulins are proteins. Proteins are always present and involved in almost every reaction in the body. The claim, as put forth in this op, however was that protein was required in the offending substance. That is clearly not true. From my last cite: a strong correlation between IgE and skin prick positivity to tobacco and bronchial challenge with cigarettes. Again, most people who react badly to passive tobacco smoke are not directly allergic, and in particular not an IgE mediated response, to an antigen in the smoke. But many do have an allergic reaction facilitated by it. And IgE responses are documented. As far as how we physicians use the word, I am not sure that there is a clear consensus. There is an official definition though.[This pdf](http://http://fds.oup.com/www.oup.com/pdf/13/9780199534968.pdf) illustrates that the official definitions by the official bodies use “allergy” to cover all the hypersensitivity classes and use “non-IgE allergy” for those that are not IgE mediated but that the practice of meaning only IgE reactions is very common. Still, [this](http://http://www.worldallergy.org/professional/allergic_diseases_center/nomenclature/english.php) is the official line and how I’ve used it. Not restricted to Type I Hypersensitivity, not exclusively IgE, not exclusively to proteins. Can be IgG or cell mediated. Can be triggered by some carbohydrates. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [September 30, 2013, 7:05am UTC](https://boards.straightdope.com/t/what-is-an-allergen/669656/33 "2013-09-30T07:05:41Z")
Is this matter resolved to everyone’s satisfaction now? [Previous page](https://boards.straightdope.com/t/what-is-an-allergen/669656.md?page=1)