Oncology & Cancer

Scientist designs 'express courier service' for immune cells

Immunotherapy is a promising cancer treatment that uses genetically modified immune cells to fight cancer. It can be used as a primary treatment or in combination with other treatments such as radiation and chemotherapy to ...

Diseases, Conditions, Syndromes

New ATS Clinical Practice Guideline: Diagnosing fungal infections

The American Thoracic Society has published an official clinical guideline on laboratory diagnosis of fungal infections in pulmonary and critical care medicine in the Society's Aug. 30 American Journal of Respiratory and ...

Oncology & Cancer

Prostate-imaging camera captures molecular detail to detect cancer

Getting a close look at the prostate is critical for detecting cancer, but its rather intimate positioning (just in front of the rectum) makes it difficult to image. Now, professor and chair of radiology Sanjiv "Sam" Gambhir, ...

Oncology & Cancer

Super-powered immune cells

The phase 1 clinical trial will test the feasibility and safety of CAR-T cells—genetically modified white blood cells harvested from a patient's own blood with the unique ability to directly attack and kill cancers—to ...

Oncology & Cancer

New vaccine strategy boosts T-cell therapy

A promising new way to treat some types of cancer is to program the patient's own T cells to destroy the cancerous cells. This approach, termed CAR-T cell therapy, is now used to combat some types of leukemia, but so far ...

Oncology & Cancer

Confining cell-killing treatments to tumors

Cytokines, small proteins released by immune cells to communicate with each other, have for some time been investigated as a potential cancer treatment.

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Antigen

An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as pollen or cells such as bacteria. The term originally came from antibody generator and was a molecule that binds specifically to an antibody, but 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 invaders and attacked by the immune system. self antigens.

An immunogen is a specific type of antigen. An immunogen is a substance that is able to provoke an adaptive immune response if injected on its own. An immunogen is able to induce an immune response, whereas an antigen is able to combine with the products of an immune response once they are made. The overlapping concepts of immunogenicity and antigenicity are, therefore, subtly different. According to a current textbook:

Immunogenicity is the ability to induce a humoral and/or cell-mediated immune response

Antigenicity is the ability to combine specifically with the final products of the immune response (i.e. secreted antibodies and/or surface receptors on T-cells). Although all molecules that have the property of immunogenicity also have the property of antigenicity, the reverse is not true."

At the molecular level, an antigen is characterized by its ability to be "bound" at the antigen-binding site of an antibody. Note also that antibodies tend to discriminate between the specific molecular structures presented on the surface of the antigen (as illustrated in the Figure). Antigens are usually proteins or polysaccharides. This includes parts (coats, capsules, cell walls, flagella, fimbrae, and toxins) of bacteria, viruses, and other microorganisms. Lipids and nucleic acids are antigenic only when combined with proteins and polysaccharides. Non-microbial exogenous (non-self) antigens can include pollen, egg white, and proteins from transplanted tissues and organs or on the surface of transfused blood cells. Vaccines are examples of immunogenic antigens intentionally administered to induce acquired immunity in the recipient.

Cells present their immunogenic-antigens to the immune system via a histocompatibility molecule. Depending on the antigen presented and the type of the histocompatibility molecule, several types of immune cells can become activated.

This text uses material from Wikipedia, licensed under CC BY-SA