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1. Introduction to immunology: Difference between revisions
→Antigen
(Created page with "== Antigen == An antigen is any molecule that can be recognized by special receptors on the T and B-cells or antibodies, and they induce either an immune response or immune tolerance. The last part is important, because an antigen isn’t just something foreign that triggers an immune attack. We mostly think of antigens as something that’s only found on pathogens like bacteria or viruses. However, every protein in your body is an antigen, but none of the proteins in yo...") |
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== Antigen == | == Antigen == | ||
[[File:Antigen vs epitope.png|thumb|The difference between antigen and epitope. The light blue squares are similar antigens, each of which have three different epitopes; one red square, one purple circle and one orange triangle. The purple antibodies can only bind the squares, the yellow ones can only bind to the circles.]] | |||
An antigen is any molecule that can be recognized by special receptors on the T and B-cells or antibodies, and they induce either an immune response or immune tolerance. The last part is important, because an antigen isn’t just something foreign that triggers an immune attack. We mostly think of antigens as something that’s only found on pathogens like bacteria or viruses. However, every protein in your body is an antigen, but none of the proteins in your body will induce an immune response, luckily! This is a part of the immune system tolerance. When tolerance is impaired the body will attack itself and there will be an autoimmune disease. | An antigen is any molecule that can be recognized by special receptors on the T and B-cells or antibodies, and they induce either an immune response or immune tolerance. The last part is important, because an antigen isn’t just something foreign that triggers an immune attack. We mostly think of antigens as something that’s only found on pathogens like bacteria or viruses. However, every protein in your body is an antigen, but none of the proteins in your body will induce an immune response, luckily! This is a part of the immune system tolerance. When tolerance is impaired the body will attack itself and there will be an autoimmune disease. | ||
Immune cells bind antigens from your own cells all the time, to check if they’re infected with a virus or are cancerous. If they are, they are killed, but if not, they are ''tolerated,'' so no response is given. Structurally, they can be anything, any protein in either your own cells or in a bacteria cell. Anything you can find in and on the outside of a cell can be an antigen. The name comes from antibody generator. | Immune cells bind antigens from your own cells all the time, to check if they’re infected with a virus or are cancerous. If they are, they are killed, but if not, they are ''tolerated,'' so no response is given. Structurally, they can be anything, any protein in either your own cells or in a bacteria cell. Anything you can find in and on the outside of a cell can be an antigen. The name comes from antibody generator, as antigens are recognised by so-called antibodies. | ||
=== Epitope === | |||
Strictly speaking, an antibody doesn’t bind to an antigen, it binds to a specific site on the antigen called the <abbr>epitope</abbr>. While an antigen is a molecule, the epitope is the specific part of the molecule that the antibody can bind to. One antigen can have many epitopes, so many antibodies can bind to the same antigen. | |||
== The immune system == | == The immune system == | ||