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medical health vaccines

What is an exogenous antigen?

Last Updated: 19th February, 2020

Exogenous antigens are antigens that have entered the body from the outside, for example, by inhalation, ingestion or injection. By endocytosis or phagocytosis, exogenous antigens are taken into the antigen-presenting cells (APCs) and processed into fragments.

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People also ask, what is the difference between endogenous and exogenous antigens?

The difference is that the peptides originate from different sources – endogenous, or intracellular, for MHC class I; and exogenous, or extracellular for MHC class II. Endogenous antigens can also be presented by MHC class II when they are degraded through autophagy.

One may also ask, which is an example of an endogenous antigen? Endogenous antigens are antigens found within the cytosol of human cells such as viral proteins, proteins from intracellular bacteria, and tumor antigens. Exogenous antigens are antigens that enter from outside the body, such as bacteria, fungi, protozoa, and free viruses.

In this manner, what is exogenous antigen processing?

The exogenous pathway is utilized by specialized antigen-presenting cells to present peptides derived from proteins that the cell has endocytosed. The peptides are presented on MHC class II molecules. Proteins are endocytosed and degraded by acid-dependent proteases in endosomes; this process takes about an hour.

What are 3 types of antigens?

Antigens are generally proteins. But they can be lipids, carbohydrates or nucleic acids. Antigens can be of three types – Exogenous, endogenous and autoantigens. Antigens can also be foreign bodies that stimulate the immune system of the body.

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Are antigens bad?

The immune system protects the body from possibly harmful substances by recognizing and responding to antigens. Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Your immune system learns to see these antigens as normal and usually does not react against them.

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Is a virus an antigen?

A virus antigen is a toxin or other substance given off by a virus which causes an immune response in its host. A viral protein is an antigen specified by the viral genome that can be detected by a specific immunological response. Viruses are complexes consisting of protein and an RNA or DNA genome.

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What are the types of antigens?

Types of Antigen On the basis of order of their class (Origin)
  • Exogenous antigens. These antigens enters the body or system and start circulating in the body fluids and trapped by the APCs (Antigen processing cells such as macrophages, dendritic cells, etc.)
  • Endogenous antigens.
  • Autoantigens.

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How many antigens are there?

All humans and many other primates can be typed for the ABO blood group. There are four principal types: A, B, AB, and O. There are two antigens and two antibodies that are mostly responsible for the ABO types.

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What is an example of an exogenous infection?

Disease can occur when microbes included in normal bacteria flora enter a sterile area of the body such as the brain or muscle. This is considered an endogenous infection. A prime example of this is when the residential bacterium E. coli of the GI tract enters the urinary tract. This causes a urinary tract infection.

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What is the meaning of endogenous and exogenous?

Exogenous comes from the Greek Exo, meaning “outside” and gignomai, meaning “to produce.” In contrast, an endogenous variable is one that is influenced by other factors in the system. In this example, flower growth is affected by sunlight and is therefore endogenous. Exogenous variables…

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Which antibody type is largest?

IgM is the largest antibody and the first one to be synthesized in response to an antigen or microbe, accounting for 5% of all immunoglobulins present in the blood. IgM typically exists as polymers of identical subunits, with a pentameric form as the prevalent one.

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How are antigens produced?

Antigens are proteins that are found on the surface of the pathogen. When an antigen enters the body, the immune system produces antibodies against it. Antibodies are always Y-shaped. It is like a battle with the army (antibody) fighting off the invader (antigen).

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What is mhc1 and mhc2?

MHC I glycoproteins are present in all nucleated cells. MHC II glycoproteins are only present on specialised antigen-presenting cells (APCs), including macrophages that engulf foreign particles such as bacteria, dendritic cells that present antigen to T cells, and B cells that produce antibodies.

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How do T cells recognize antigens?

T cells recognize antigens with their antigen receptor, a complex of two protein chains on their surface. They do not recognize self-antigens, however, but only processed antigen presented on their surfaces in a binding groove of a major histocompatibility complex molecule.

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What is the purpose of antigen presentation?

Antigen presentation describes a vital immune process which is essential for T cell immune response triggering. If there has been an infection with viruses or bacteria, the cell will present an endogenous or exogenous peptide fragment derived from the antigen bound to MHC molecules.

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What is the process of antigen presentation?

Antigen presentation. Antigen presentation is the process by which protein antigen is presented to lymphocytes in the form of short peptide fragments. These are associated with antigen-presenting molecules such as MHC class I or MHC class II on the surface of antigen-presenting cells (APCs).

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Why is antigen important in fighting infection?

Why is antigen-presentation important in fighting infection? Infected cells actively make viral proteins and present it on their surface. Cytotoxic T cells have TCR's and CD8 receptors on their surface. When their TCR's match the viral antigen, they proceed to kill the infected cells.

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How are B cells activated?

B-cells are activated by the binding of antigen to receptors on its cell surface which causes the cell to divide and proliferate. Some stimulated B-cells become plasma cells, which secrete antibodies. Others become long-lived memory B-cells which can be stimulated at a later time to differentiate into plasma cells.

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What is the role of MHC class 1?

MHC class I. Their function is to display peptide fragments of proteins from within the cell to cytotoxic T cells; this will trigger an immediate response from the immune system against a particular non-self antigen displayed with the help of an MHC class I protein.

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How does cross presentation work?

Cross-presentation is the ability of certain antigen-presenting cells to take up, process and present extracellular antigens with MHC class I molecules to CD8 T cells (cytotoxic T cells). The MHC I pathway is normally used to present endogenous antigens that have infected a particular cell.



How do helper T cells activate cytotoxic T cells?

Helper T cells do not directly kill infected cells, as cytotoxic T cells do. Instead they help activate cytotoxic T cells and macrophages to attack infected cells, or they stimulate B cells to secrete antibodies. Helper T cells become activated by interacting with antigen-presenting cells,…

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What is the difference between antigen and epitope?

An epitope (also known as the antigenic determinant) is that part of the antigen to which antibodies bind. While the antigen evokes the antibody response in the host, the antibody doesn't bind to the entire protein, but only to that segment called the epitope.

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What is a characteristic of antigens?

Most antigens have a large molecular weight and are chemically composed of proteins or polysaccharides, but may also be lipids, polypeptides, or nuclear acids, among others. There are low-molecular weight substances which are capable of producing an immune response, called haptens.