Talk:Antigen

YO! Way To techy

Dudes. How about writing this over in English?--149.152.34.80 (talk) 21:55, 17 May 2009 (UTC)

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Yes, this was written by an idiot. This is wikipedia not your biology textbook. Also, consider the idea of complexity ramp. What idiot hits the reader with this first sentence:

"In immunology, antigens (Ag) are structures (aka substances) specifically bound by antibodies (Ab) or a cell surface version of Ab ~ B cell antigen receptor (BCR)."

--93.73.58.129 (talk) 20:53, 20 April 2019 (UTC)

This is like vandalism. You would have been better not making any addition. Is this autism?

-93.73.58.129 (talk) 20:55, 20 April 2019 (UTC)

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Too technical

1st para is incomprehensible to those who don't already know what an antigen is. And then what would be the point of the Wikipedia? Showing off? --189.130.3.218 (talk) 04:28, 26 July 2015 (UTC)

Should the header Freefloating Antibodies be Freefloating Antigens?

This paragraph doesn't match what I'm reading in other articles. Is this paragraph implying that polyclonal antibodies cannot attack free floating antigens?

I think you'd be dead very soon and very quick if you only had monoclonal antibodies in your bloodstream. (By their nature monoclonal systems are an artificial construct for research/therapy - did that make sense?) Changing that right now, will come back and do a whole overhaul--ZZ 14:59, 1 Oct 2004 (UTC)

Should this article be reworked? The wording is a bit odd and mostly not correct (although it is very easy to read, especially for the non-scientist). User:Stmoran, 14 May 2005

Of course it should be. That's the point of the process. If you revise it in a way we don't like, it is always possible to change or revert it. Also remember to sign yourself using four tildes ~~~~ --Eleassar777 11:17, 14 May 2005 (UTC)

definitions of Endogenous versus Exogenous antigens do not match definitions elsewhere on wikipedia (or the literature)

Source: https://en.wikipedia.org/wiki/Antigen_processing#The_exogenous_pathway Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4026165/ All antigens come from outside the body by the most basic definition (foreign substance). There are of course multiple definitions as other users point out here, but classifying exogenous antigens as foreign (outside the body) suggests endogenous antigens are self-antigens (inside the body), which is incorrect. Exogenous versus endogenous antigens refers to where the antigens are located relative to a cell, not the entire body. This has important implications on how antigens are processed and loaded up onto MHC, then displayed to Tc or Th lymphocytes. Endogenous antigens start from within the cytoplasm (infected cells or nucleotide-based vaccines) and are loaded onto MHCI, while exogenous antigens are those engulfed by Antigen Presenting Cells (such as macrophages or activated B cells), they never enter the cytoplasm, and are loaded onto MHC II. At the very least, it should be mentioned there are multiple definitions of endogenous versus exogenous in the fields of biology, but in immunology there is a special and important set of definitions for these two words. This concept is very important for understanding whether Tc or Th cells are activated (which is a difference in life or death for the cell with an antigen). Laird.sheldahl (talk) 16:45, 10 June 2022 (UTC)

Antigen Correction of DEFINITION

An antigen is ANY BODY that stimulates antibody prouction, from the immune system against it. Source: http://www.nlm.nih.gov/medlineplus/ency/article/002224.htm --Chazz88 22:08, 11 October 2005 (UTC)

Antigen vs. Immunogen

In my immunology course I was given slightly different definitions for antigen and immunogen. According to what I learned, antigens are substances that can bind to components of the immune system, but not necessarily cause an actual immune response. An immunogen, however, was defined as a substance that can cause an acquired immune response. The definition for antigen given in this article is different. Any thoughts? -Campaigner444 00:46, 4 November 2005 (UTC)

I agree, an immunogen is not the same thing as an antigen XApple (talk) 16:13, 7 June 2008 (UTC)

I agree as well. An immunogen is a type of antigen, but not all antigens are immunogens. As you have said, immunogens elicit a response from the immune system, but antigens do not always cause a reaction. There should be some differentiation.--Mcoj87 (talk) 19:10, 9 December 2008 (UTC)

That's what I was taught by my prof. too. 75.155.134.185 (talk) 21:44, 26 December 2008 (UTC)

If they're two separate entities with two different sets of attributes, they should be split. Encyclopedic articles aren't pan-topical.--Cesium_133 (talk) 13:17, 29 April 2009 (UTC)

Removed text

It is widely recognized by medical professionals that menstrual fluid contains a bacteria associated with Daujeszky's Disease, a antigen in men that has gone unrecognized for many years. Known side effects include stomach cramps, nausea, diarrhea, and severe inflammation of the urethra. If not treated properly it could result in urinary infection lasting for up to several days.

A finding of Dr. Joan Hiniesne, a professor at Cambridge University, suggests that Daujeszky’s Disease occurs primarily in young sexual active men. A case study in Austin, Texas followed a man, “Dave” (hiding actual name under privacy clause), for several months after having intercourse during the menstrual cycle of a female participant. The study concluded that symptoms often arise fairly suddenly and last for any number of days; perhaps even weeks depending on severity. “This is a very common effect of intercourse during the menstrual cycle” Reported by Casey Snyder of the Washington Medical Journal in an article entitled: Presumptions of Safety during Sex.

information by User:Kjsogjs (contributions) over four edits 7 February 2007

removal --ZayZayEM 01:19, 7 February 2007 (UTC)

"Origin of poopy", vandalization, right?

that is the result of vandalism, right? 0.0 --TiagoTiago (talk) 10:14, 20 November 2007 (UTC)

I hope it is ok, I reverted the poopy thing--TiagoTiago (talk) 10:24, 20 November 2007 (UTC)

This page contains false information

The basic definition given on this page (i.e. antigen = immunogen) is wrong. There needs to be two separate articles. One is a sub-class of the other.

Immunogens refer to antigens that are able to stimulate a specific adaptive immune response when introduced into the body. Not all antigens are immunogens. To be immunogenic, antigens must fulfil certain criteria, such as i/ being large enough, ii/ chemically complex and iii/ in most of the cases foreign.

For instance a hapten is an antigenic substance but not immunogenic. XApple (talk) 17:24, 8 June 2008 (UTC)

Chemical Composition

This article should discuss the chemical composition of antigens. As well as their structure, capabilities... —Preceding unsigned comment added by 76.106.58.112 (talk) 01:08, 14 May 2009 (UTC)

practical examples

What are practical examples of antigens ? Are they vaccines and antitoxins ? Include to article

Article title

Why is the article entitled "Antibody generator"? "Antigen" is far more commonly used in the UK. Also, the text of the article uses the term "antigen", not "antibody generator". Axl ¤ [Talk] 10:44, 29 August 2009 (UTC)

Agree that "antibody generator" is not a widely used term (although it does make the "antigen" concept explicit). After reading the discussions and the article, I think the title should be "immunogen" and that "antigen" should be a subheading within the article. Immunology is complicated with several overlapping concepts, but to the best of my understanding this is the correct heirarchy Johnfravolda (talk) 14:27, 29 August 2009 (UTC)

Agreed. The term simply isn't used, and probably wouldn't be recognized if it was. Similarly, we have a modem article, not a modulator-demodulator article. – ClockworkSoul 02:56, 30 August 2009 (UTC)

I doubt that the term "antibody generator" has ever been used. It (and the reference) should be dropped. —Preceding unsigned comment added by Rstenutz (talk • contribs) 14:27, 15 July 2010 (UTC)

Definitional issue

I removed my previous comments on the relationship between the concepts of "immunogen" and "antigen" since my case contradicts the authority of accepted text books on the subject.

In reviewing "Kuby Immunology" I read:

"Antigens are defined specifically as molecules that interact with the immunoglobulin receptor of B-cells (or with the T-cell receptor when complexed with MHC)."

This is clearly a bit different from the concept of "antibody generator" from which the term antigen derives (see Antigen#Origin_of_the_term_antigen).

Also, even the Kuby definitions has its caveats, since "molecules that interact with the immunoglobulin receptor" would include molecules that can attach to antibodies (immunoglobulins) in their own right. For example, a molecule like protein A "attacks" antibodies by binding to invariable regions of immunoglobulin molecules without acting as an antigen. Of course, protein A can also act as an immunogenic-antigen since it is a "non-self" molecule that would induce the production of anti-protein A antibodies.

So it seems that it is not easy to arrive at a precise, logical and historically consistent definition of "antigen".

Suggest removing "Split", "Citations" and "Original research" tags from article

Any thoughts on current state of the article?

Making this page accessible to most readers

Here is the current lead paragraph of the article:

An antigen (from antibody generator) originally defined as any molecule that binds specifically to an antibody, the term now also refers to any molecule or molecular fragment that can be bound by a major histocompatibility complex (MHC) and presented to a T-cell receptor. "Self" antigens are usually tolerated by the immune system; whereas "Non-self" antigens are identified as intruders and attacked by the immune system. Autoimmune disorders arise from the immune system reacting to its own antigens.

And here is the definition from the MedlinePlus website of the National Institutes of Health:

"An antigen is any substance that causes your immune system to produce antibodies against it. An antigen may be a foreign substance from the environment such as chemicals, bacteria, viruses, or pollen. An antigen may also be formed within the body, as with bacterial toxins or tissue cells."

Now which one do you think most readers would understand?

This page needs to be seriously reworked by an expert who knows how to write for people who aren't themselves experts already. -- Mwalcoff (talk) 02:02, 10 March 2010 (UTC)

Bravo! Go with the NIH definition.108.65.90.133 (talk) 04:07, 28 June 2013 (UTC)

ANON READER Someone please fix this article. It is amateur at best and half the definitions are incorrect. An antigen isn't defined by presence of a foreign macromolecule alone, it also includes self. — Preceding unsigned comment added by 157.182.148.39 (talk) 16:44, 7 December 2011 (UTC)

Topic sentence

What is the topic sentence even trying to say? To a non-technical reader, this means nothing at all: "In immunology, TCR or BCR or its secreted form antibody." Can someone please either clarify this or remove it? Daemon328 (talk) 16:37, 29 January 2016 (UTC)

I came on here to raise the same point. The opening sentence is not a complete sentence. I don't have the scientific knowledge to figure out what's intended, but it would be wonderful if someone who did could fix it. Tigercompanion25 (talk) 18:07, 5 February 2016 (UTC)

@Daemon328: and @Tigercompanion25:, I just edited the top paragraph and it should now read more clearly. In fact, the first sentence Daemon328 quoted is actually grossly incorrect (BCR is not antigen but antibody, and TCR is a different type of molecule altogether). I had edited this same page not long ago, and so I apologize for not having paid more attention previously; I only noticed this issue after reading your exchange here. _themidget17 | babble 21:19, 5 February 2016 (UTC)

Thank you @Themidget17:, it looks crisp and clear now. :) Tigercompanion25 (talk) 23:48, 5 February 2016 (UTC)

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What's an antigen?

In the light of the coronavirus situation I came here to find out; I'm none the wiser. The article is essentially just techno-babble. Could someone who knows the subject modify the lead so that the layman can understand it? Incidentally, I note the first comment on the Talk page, from 2009, makes a similar request. Arcturus (talk) 12:25, 5 April 2020 (UTC)

Antigen is just something that may induce an immune response, specifically by binding to antibodies. I think perhaps you can explain what it is that you don't understand, then it would help others to explain it further. I don't think the current lead explains it very well, but you can have a look in some older versions and see if you find them better - [1][2], etc. Sometimes technical things are difficult to simplify, if you do it too simple, it might not be accurate (I see a version in Simple English and I'm not sure I'm happy with it). Hzh (talk) 13:55, 8 April 2020 (UTC)

An anti-gen 'gen'-erates an 'anti'-body response (anti-(body response) generator). So often it is something that doesn't naturally belong to the body that the immune system recognises as a potential threat and seeks to deal with. Often it could be a virus or a bacteria. The immune system sees that the antigen has something odd about it, perhaps an unusual protein on the outside, and antibodies are generates that bind to the odd feature. In essence, the antibody tags the foreign body as foreign and the rest of the immune system is alerted by the tagging to deal with it. The immune system is complicated (it is really a number of systems) so this is only a rough and ready account. Acorrector (talk) 15:51, 7 December 2020 (UTC)

I also do not understand the lead. It says an antigen "can bind to a specific antibody or T-cell receptor". But The Structural Basis of Antibody-Antigen Recognition says antibodies "bind specifically to their target antigens". It may be that the binding between two molecules is a joint property of them, but my understanding (and I am not an immunologist) is that an antigen is associated with a disease and an antibody fights the disease. So the antibody "wants" to bind to the antigen, but the disease would "prefer" that the antigen does not bind to an antibody. The lead seems to put this the wrong way round. JonH (talk) 23:12, 15 October 2021 (UTC)

That's an excellent point, and it raises some other points I think are important concepts that have not been addressed adequately for undergraduate students. You (the OP) are correct binding is a joint property. That means the first sentence is technically correct, but is technicality the goal? I think the definition the OP cites is much clearer. I would suggest changing "can bind to" to something more like "could be recognized by".. That would also be technically correct, but hints at functionality in a way that saying antigens bind to antibodies does not. That could therefore help clarify a difference between two very similar (and potentially confusing) words: anti-gen versus anti-body.

The function of antigens is not to bind to antibodies, even if antigens can do that. Antigens are often a small part of larger proteins or carbohydrates that have very specific functions, such as allowing pathogens to infect a specific type of cell (such as HIV infecting Th cells) or otherwise survive and reproduce. To have such a specific function requires a very specific shape, and the human immune system has adapted to target and exploit this specificity. Conversely, molecules with generic shapes, such as plastics or metals used in implants, are not recognized by antibodies or TCRs. Laird.sheldahl (talk) 17:13, 10 June 2022 (UTC)

Antigen source.

Antigen source. I'm assuming that antigens are trigger proteins that are originally found on viruses and vaccines that are introduced from weakened or dead viruses. These are what antibodies are formed from and reside in the body for future infection reaction? Antigens are not created by the body in response to infection being detected? 2601:187:8080:2310:E08E:5137:1C7A:4BBD (talk) 15:26, 1 January 2022 (UTC)