Antigene

Antigene is a term used in the field of immunology and molecular biology to describe a substance or molecule that, when introduced into the body, triggers an immune response by causing the production of an antibody as part of the body's defense against disease and infection. Antigenes are typically foreign substances to the body, such as bacteria, viruses, fungi, parasites, or chemical substances, and can also include allergens and other compounds that can induce an allergic reaction.

Types of Antigenes

Antigenes can be classified into several types based on their source and the immune response they elicit:

• Exogenous antigenes: These are external antigenes that enter the body from the environment, such as those found in microbes or chemicals. They are processed by antigen-presenting cells (APCs) and presented to T cells.
• Endogenous antigenes: These antigenes are generated within normal or cancerous cells and are presented by Major Histocompatibility Complex (MHC) molecules on the cell surface to T cells.
• Autoantigenes: These are the body's own proteins that are recognized as foreign by the immune system, leading to autoimmune diseases.

Antigene Recognition

The specific recognition of antigenes by the immune system is a critical aspect of the immune response. B cells and T cells are the primary lymphocytes involved in antigen recognition. B cells recognize antigenes through their B cell receptors (BCRs), while T cells recognize fragments of antigenes that are presented on the surface of cells by MHC molecules through their T cell receptors (TCRs).

Antigene Presentation

Antigene presentation is a process where antigenes are displayed on the cell surface by MHC molecules. This process is crucial for the activation of T cells, which play a significant role in the immune response. There are two main pathways for antigen presentation:

• MHC class I pathway: This pathway presents endogenous antigenes to CD8+ T cells.
• MHC class II pathway: This pathway presents exogenous antigenes to CD4+ T cells.

Role in Vaccination

Antigenes are key components in the development of vaccines. Vaccines contain antigenes that stimulate the immune system to produce antibodies and memory cells without causing the disease. This prepares the immune system to recognize and fight the specific pathogen in the future.

Autoimmune Diseases and Allergies

In some cases, the immune system may mistakenly recognize the body's own cells or harmless substances as antigenes, leading to autoimmune diseases or allergies. In autoimmune diseases, such as rheumatoid arthritis or type 1 diabetes, the immune system attacks the body's own cells. In allergies, the immune response to harmless substances, such as pollen or certain foods, can cause symptoms ranging from mild to severe.

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