Questions tagged [antigen]

An antigen is a substance which causes the the body to produce a reaction of the adaptive immune system. Contact of the immune system to antigens results in the production of highly specific (antigen specific) antibodies.

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What is the smallest molecule that can present as an antigen to the immune system in the context of allergies?

People often claim, in a colloquial sense, that they are "allergic to everything". Is it possible to have a full-fledged IgE mediated allergic response to very small molecules? I was always under ...
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What is a positive epitope fragment

What is a positive epitope fragment? I found one paper on the subject: COBEpro: a novel system for predicting continuous B-cell epitopes by Michael J. Sweredoski and Pierre Baldi
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What is cross-immunoreactivity, and how does it impact vaccine development?

What I understand about cross-immunoreactivity is that the antibody induced by one specific antigen is also fairly effective against another antigen. How would this be used for vaccine development? ...
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Synthesis of immunoglobulin Fab fragments: Where can I learn about Fab?

I wanted to know the chemical reaction involved in Fab synthesis. I looked everywhere for it. No luck. I know I will find it here. All I know for now is: Fab is a monovalent fragment that is ...
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What happens when you mix type A with type B blood (and v.v)

What happens when you mix different blood types that are not compatible? For example, if a patient has type A blood and receives type B blood, or v.v.?
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How do scientists discover a new antigen and its epitope?

I've found some database on the internet that list all discovered antigens and their epitopes. So how do scientists discover a new antigen? Do they try to inject them into the body to see if it ...
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How is a T lymphocyte specific to an antigen but not specific to an epitope?

In my immunology notes, it states that B lymphocytes (and other APCs) capture and present antigens to T lymphocytes that is specific for an antigen, but that the T cells do not necessarily recognise ...
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Minimum size for a peptide/protein to be immunogenic in human?

What is the minimum size for an (injected) peptide/protein to cause immunogenic response in human? A reference is very helpful, as well. Thanks in advance
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Autoimmunity and central tolerance

Where in the body are self antigens important? In terms of central tolerance and autoimmunity, but also in terms of T cell activation?
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Can we produce synthetic red blood cells lacking antigens?

I had an idea come to me during Biology class and I immediately asked my teacher, but she couldn't really answer the question, so I'll ask it here. What are the limiting factors in the production of ...
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Immune reaction to “new” protein

I read in Bruce Alberts Molecular Biology of the cell : Normal mice,for example, cannot make an immune response against one of their own protein components of the complement system called C5. ...
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Autoimmunity - negative selection of T-cells - APC

Through negative selection of T-cell in the thymus T-cells lose the possibility to react to antigens which are "body own" -> self antigens. Though there are more than just this negative selection for ...
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How does adjuvant enhance the immunogenicity of antigen? [closed]

My question is, How does adjuvant enhance immunogenicity of antigen? I just want to know deeply about it , Any suggestions will be helpful!
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Can more than one antibody bind the same antigen

I'd like to clear something up about antibodies that I'm not sure I've understood in the articles I've read. Looking at concepts such as "affinity maturation", "monovalent antigens" and "polyvalent ...
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How to inhibit formation of specific antibodies (to antisera)?

Is there a way to inhibit an antibody response to a specific antigen using immunosupression? I am interested in reducing the anti-antibody formation to animal antibodies such as murine antibodies in ...
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Are there any antigen electronic sensors? [closed]

Is it possible somehow to attach antibody to silicon or to other electronic component chemical, and have electronic detector of correspondent antigen? Does such devices exist?
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Can multiple antibodies bind the same antigen?

Given the size difference between small molecule antigens and antibodies is it ever possible for multiple antibodies to bind to the same antigen if they recognize different domains on that antigen? ...
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CD4 Proteins & Antigen presenting cells

If Helper T-Cells express CD4+ proteins on their surface to bind to MHC Class ll proteins on antigen presenting cells, why do antigen presenting cells also have CD4+ Proteins?
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Can you Transfer Cancer Between People via Saliva or other Bodily Fluids?

This may sound like a strange question. But could a Cancerous cell be transferred from one person to another from Oral contact e.g. Through Saliva, or other exchange of bodily fluids? I know that ...
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human anti-mouse antibody

I have heard about human anti-mouse antibodies (HAMAs) and read that HAMAs neutralize murine antibodies, therefore decreasing the effectiveness of those murine antibodies. Is this true that HAMAs ...
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Agglutination test using antibodies

Agglutination test Latex agglutination using bound antigens : by coating soluble (non - particulate ) antigens on to microscopic latex spheres, their reaction with a particular antibody can be ...
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Can MHC class I be used for presenting peptides of extracellular origin by non-professional APCs?

Wikipedia says that: "The antigens presented by MHC class II are derived from extracellular proteins (not cytosolic as in MHC class I)." So does this mean that MHC class I cannot be used for ...
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How does one predict how large of an effect on antigenic drift a substitution in the amino acid sequence of a surface protein of influenza has?

I know that some amino acid substitutions are more effective in causing antigenic drift than other substitutions based on their location in the 3d structure of the HA protein (proximity to the ...
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Why does the blood not clump and result in death?

In this question's accepted answer, it is said that the blood type will slowly change to that of the donor's. When the blood in the person is about 50% his own and 50% that of the donor's. i.e, 50% A ...
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What attracts cells to: pathogens, professional antigen-presenting cells, and cells with an antigen on its MHC-1 protein?

I have a few questions in regards to attraction/stimulation in the immune system. What attracts leukocytes and antibodies to pathogens in the first place? What attracts CD4+ cells to professional ...
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Vaccines against bacterial endotoxins

Today in class, there was a discussion going on about what part of pathogens(which can act as an antigen) can be used to make vaccines. There was this point where our teacher said that bacterial ...
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How does HBeAg change to Anti-HBe in acute hepatitis

I am thinking this figure which can also be drawn like this How does HBeAg change to Anti-HBe? There are some triggers that stimulate Anti-HBe production after HBeAg level is done. I think they ...
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What is meant by 'fixing' of an antigen presenting cell?

Can someone please explain what does 'fixing' of an antigen presenting cell mean?
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Do allergens have structural similarities to pathogens?

The conventional popular explanation of allergies is that the immune system confuses allergens with pathogens and reacts to them as such. Is there any merit to this explanation? If so, I would ...
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O-Group names of Salmonella serotypes?

What liposaccharides are represented by the O-group designations of Salmonalla serovars in the Kauffman-White classification scheme? I mean to ask, how do the numbers in a Sal serovar (1, 9, & 12 ...
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What are blood group determinants? [closed]

I am trying to understand if they are the same as the blood antigens. The books I have tried to read say something about them being the antigens on the surface of the red blood cell.
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Could transfusion of a different blood type cure blood-based cancers?

Different antigen detection triggers an immune system response that could perhaps stimulate mitochondria and such in killing cancer cells - something like chemo without the hair-loss?
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Choosing viruses for influenza vaccine

When scientists choose viruses for the influenza vaccine based on biological and clinical data, what indicates that a certain strain will circulate and likely be dominant in a certain season? Does a ...
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Will a sandwich assay work with a GST 26 antibody/protein?

I have a GST 26 kda antibody, and want to use it in a sandwich lateral flow assay. Are there enough epitope regions for both antibodies to bind to the protein?
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Detect which antigen binds to IgE

Assume that a patient has chronic hives (itchy) on the skin. I understand that he has an antigen, which binds to IgE and eventually triggers histamine release, causing an allergic reaction. So is ...
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Are antibodies and hepatitis viruses of similar adaptability?

Antibodies and Hepatitis viruses both have hypervariable regions. Is one more adaptable than the other? Precisely how adaptable are they? I have read that antibodies can be trained to bind to ...
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Why are vaccines a successful treatment of allergy?

As I understand the answer to Allergic rhinitis vaccine, the vaccine facilitates immune response against the antigen. Given that allergy is an overreaction of the immune system against harmless ...