Specific immunity may be either genetic - an inherited ability to resist certain diseases because of one's species, race, sex, or individual genetics - or acquired. Specific immunity is dependent on the body's ability to identify a pathogen and prepare a specific response (antibody) to only that invader (antigen). antibodies are also referred to as immunoglobulins (lg). The acquired form can be further divided into natural and artificial forms, which in turn can each be either active or passive. After a description of the specific immune process, each of the four types is discussed. Did You Know?
Specific immunity is dependent on the agraulocytes (lymphocytes and monocytes) for its function. The monocytes metamorphose into macrophages, which dispose of foreign substances. The lymphocytes differentiate into either T lymphocytes (they mature in the thymus) or B lymphocytes (they mature in the bone marrow or fetal liver). Although both types of lympocytes take part in specific immunity, they do it in different ways.
The T cells neutralize their enemies through a process of cell-mediated immunity. This means that they attack antigens directly. They are effective against fungi, cancer cells, protozoa, and unfortunately, organ transplants. B cells use a process of humoral immunity (also called antibody-mediated immunity). This means that they secrete antibodies to "poison" their enemies.
Types of Acquired Immunity
Acquired immunity is categorized as active or passive and then is further subcategorized as natural or artificial. All describe ways that the body has acquired antibodies to specific diseases.
Active acquired immunity can take either of the following two forms:
- Natural: Development of memory cells to protect the individual from a second exposure.
- Artificial: Vaccination (immunization) that uses a greatly weakened form of the antigen, thus enabling the body to develop antibodies in response to this intentional exposure. Examples are the DTP and MMR vaccines.
Passive acquired immunity can take either of the following two forms:
- Natural: Passage of antibodies through the placenta or breast milk.
- Artificial: Use of immunoglobulins harvested from a donor who developed resistance against specific antigens