Active

Active Immunity

Active immunity is a type of immunity that results from the production of antibodies by the immune system in response to the presence of an antigen. It is the immunity that occurs after exposure to an infectious disease or through vaccination.

Mechanism of Action

Active immunity is achieved when the body's immune system produces antibodies or T cells in response to an antigen. This can occur naturally, when a person is exposed to a pathogen, or artificially, through vaccination. The immune system's response to an antigen involves a complex series of events known as the immune response.

When an antigen enters the body, it is recognized by antigen-presenting cells (APCs), which engulf the antigen and present fragments of it on their surface. These fragments are recognized by T cells, which then stimulate B cells to produce antibodies. These antibodies bind to the antigen, neutralizing it and marking it for destruction by other immune cells.

Types of Active Immunity

There are two types of active immunity: natural and artificial.

• Natural active immunity occurs when a person is exposed to a live pathogen, develops the disease, and becomes immune as a result of the primary immune response. This is long-lasting and often lifelong immunity.

• Artificial active immunity is induced by a vaccine, a substance that contains the antigen. Vaccines stimulate a primary response against the antigen without causing symptoms of the disease.

Benefits and Risks

Active immunity provides long-term protection against diseases, as it involves the production of memory cells that can quickly respond to subsequent exposures to the same antigen. However, it takes time to develop, and there may be discomfort from symptoms of the immune response.

The main risk of active immunity is that the immune response it triggers may be too strong, leading to an immune system disorder. This is rare, but can be serious when it occurs.

Diagram showing the process of active immunity

See Also

• Passive immunity
• Herd immunity
• Vaccination
• Immunology

References

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