Related topics: immune system · hiv · vaccine · protein · virus

Fungi in the gut prime immunity against infection

Common fungi, often present in the gut, teach the immune system how to respond to their more dangerous relatives, according to new research from scientists at Weill Cornell Medicine. Breakdowns in this process can leave people ...

Detecting COVID-19 antibodies in 10 seconds

Researchers at Carnegie Mellon University report findings on an advanced nanomaterial-based biosensing platform that detects, within seconds, antibodies specific to SARS-CoV-2, the virus responsible for the COVID-19 pandemic. ...

How to use antibodies to control chemical reactions

In a collaborative effort a group of international scientists has recently demonstrated a way to control different synthetic chemical reactions with specific antibodies. Their work has been now published in Nature Communications.

'Nanobodies' could hold clues to new COVID-19 therapies

WEHI researchers are studying 'nanobodies' – tiny immune proteins made by alpacas—in a bid to understand whether they might be effective in blocking SARS-CoV-2, the virus that causes COVID-19.

Chromatin regulation enables generation of diverse antibodies

We need a variety of antibody types to help fight off invading foreign pathogens and our genome is exquisitely tuned to produce them to meet emerging needs. A new study finds that not just our DNA, but its configuration and ...

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Antibody

Antibodies (also known as immunoglobulins, abbreviated Ig) are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacteria and viruses. They are typically made of basic structural units—each with two large heavy chains and two small light chains—to form, for example, monomers with one unit, dimers with two units or pentamers with five units. Antibodies are produced by a kind of white blood cell called a plasma cell. There are several different types of antibody heavy chains, and several different kinds of antibodies, which are grouped into different isotypes based on which heavy chain they possess. Five different antibody isotypes are known in mammals, which perform different roles, and help direct the appropriate immune response for each different type of foreign object they encounter.

Although the general structure of all antibodies is very similar, a small region at the tip of the protein is extremely variable, allowing millions of antibodies with slightly different tip structures, or antigen binding sites, to exist. This region is known as the hypervariable region. Each of these variants can bind to a different target, known as an antigen. This huge diversity of antibodies allows the immune system to recognize an equally wide diversity of antigens. The unique part of the antigen recognized by an antibody is called an epitope. These epitopes bind with their antibody in a highly specific interaction, called induced fit, that allows antibodies to identify and bind only their unique antigen in the midst of the millions of different molecules that make up an organism. Recognition of an antigen by an antibody tags it for attack by other parts of the immune system. Antibodies can also neutralize targets directly by, for example, binding to a part of a pathogen that it needs to cause an infection.

The large and diverse population of antibodies is generated by random combinations of a set of gene segments that encode different antigen binding sites (or paratopes), followed by random mutations in this area of the antibody gene, which create further diversity. Antibody genes also re-organize in a process called class switching that changes the base of the heavy chain to another, creating a different isotype of the antibody that retains the antigen specific variable region. This allows a single antibody to be used by several different parts of the immune system. Production of antibodies is the main function of the humoral immune system.

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