Acquired immunity

Acquired Immunity is a type of immunity that is developed in an organism by exposure to a foreign substance, or antigen. This form of immunity can be either natural or artificial, and is characterized by specificity, memory, and self/non-self recognition.

Overview

Acquired immunity is also known as adaptive immunity or specific immunity. It is the third line of defense in the immune system, following the physical and chemical barriers of the skin and mucous membranes, and the innate immune system. Acquired immunity is unique in that it is able to recognize and remember specific pathogens, leading to a stronger immune response upon subsequent exposures.

Types of Acquired Immunity

There are two main types of acquired immunity: active and passive.

Active Immunity

Active immunity is immunity that results from the production of antibodies by the immune system in response to the presence of an antigen. This can occur naturally, when a person is exposed to a pathogen and their immune system responds, or artificially, through vaccination.

Passive Immunity

Passive immunity is the transfer of active humoral immunity in the form of ready-made antibodies. This can occur naturally, such as the transfer of antibodies from mother to child during pregnancy and breastfeeding, or artificially, through the administration of antiserum or monoclonal antibodies.

Mechanisms of Acquired Immunity

Acquired immunity involves the activation of lymphocytes, which are a type of white blood cell. There are two main types of lymphocytes involved in acquired immunity: B cells and T cells.

B Cells

B cells are responsible for producing antibodies in response to an antigen. These antibodies bind to the antigen, marking it for destruction by other cells of the immune system.

T Cells

T cells are responsible for a variety of functions in the immune system, including killing infected cells, activating other immune cells, and regulating immune responses.

See Also

• Innate immunity
• Immune system
• Vaccination
• Antibody
• Antigen