Active immunity

Active Immunity

Active immunity is a form of acquired immunity that develops in response to exposure to an antigen. This type of immunity involves the activation of the immune system to produce antibodies and memory cells, which provide long-term protection against specific pathogens. Active immunity can be acquired naturally through infection or artificially through vaccination.

Mechanism of Active Immunity

Active immunity involves the recognition of antigens by the immune system, leading to the activation of B cells and T cells. Upon exposure to an antigen, B cells differentiate into plasma cells that produce specific antibodies. These antibodies bind to the antigen, neutralizing it or marking it for destruction by other immune cells. T cells, on the other hand, can directly kill infected cells or help coordinate the immune response.

The key feature of active immunity is the formation of memory cells. These cells "remember" the specific antigens and can mount a rapid and robust response upon subsequent exposures. This memory response is the basis for the long-lasting protection provided by active immunity.

Types of Active Immunity

Natural Active Immunity

Natural active immunity occurs when an individual is exposed to a pathogen and the immune system responds by producing antibodies and memory cells. For example, recovering from diseases such as measles or chickenpox results in natural active immunity.

Artificial Active Immunity

Artificial active immunity is achieved through vaccination. Vaccines contain antigens that stimulate the immune system without causing the disease. This process leads to the production of antibodies and memory cells, providing protection against future infections. Common vaccines include those for influenza, hepatitis B, and human papillomavirus (HPV).

Advantages of Active Immunity

- Long-lasting protection: Active immunity provides long-term protection due to the presence of memory cells. - Specificity: The immune response is specific to the pathogen, ensuring targeted defense. - Boostable: Immunity can be enhanced through booster vaccinations.

Limitations of Active Immunity

- Time to develop: It takes time for active immunity to develop after initial exposure to an antigen. - Initial vulnerability: Individuals may be susceptible to infection before immunity is fully established.

Also see

- Passive immunity - Immune system - Vaccination - Antibody - Memory cell