Understanding Cellular and Acquired Immunity: Types, Mechanisms, and Pathologies
Classified in Biology
Written at on 
English with a size of 3.04 KB.
Cellular Immunity
Cellular immunity involves two main types of lymphocytes: T lymphocytes and B lymphocytes. It also involves non-T, non-B cells. This system effectively destroys:
- Foreign cells
- Tumor cells
- Virus-infected cells
- Cells infected by intracellular pathogens
T Lymphocytes
T4 Lymphocytes
TH Lymphocytes: These cells stimulate other T cells and B lymphocytes.
TD Lymphocytes: These cells increase the number and activity of macrophages.
T8 Lymphocytes
TC Lymphocytes: These cells destroy target cells.
TS Lymphocytes: These cells regulate and suppress excessive or inappropriate immune responses. They deactivate lymphocytes once antigenic agents are controlled.
A phagocyte captures a foreign element, digests it, and presents it as an antigen-presenting cell. This complex binds to the T cell antigen receptor, activating the T cell. When TH cells are activated, they also activate TC and TS lymphocytes.
Non-T, Non-B Cells
These cells perform specific responses. There are two main types:
- K cells: Attack antibody-coated cells.
- NK cells: Function similarly to K cells.
Types of Immunity
Innate Immunity
Innate immunity involves non-specific defense mechanisms.
Acquired Immunity
Acquired immunity involves defense mechanisms developed through exposure to antigens.
Acquisition of Acquired Immunity
Active Immunity
Active immunity is acquired after producing an immune response, leading to immunological memory.
Natural Active Immunity: Acquired through an unprovoked immune response.
Artificial Active Immunity: Induced by vaccines.
Passive Immunity
Passive immunity occurs when antibodies conferring immunity are produced by another individual. Its effect is temporary and doesn't create lasting immunological memory.
Natural Passive Immunity: Antibodies naturally pass from mother to child.
Artificial Passive Immunity: Antibodies are introduced into the body from an external source.
Pathologies
Immune Tolerance
A specific state of non-response to an antigen.
Autoimmunity
The immune system fails to recognize its own cells and molecules, producing an immune response against itself.
Hypersensitivity
An exaggerated response against pathogens. Allergy is a response to a normally harmless substance (allergen). Allergic responses vary.
Immunodeficiencies
Absence or failure of the normal function of one or more elements of the immune system.
Tumor Immunity
Tumor cells recognized as foreign trigger an immune response.
Transplant Rejection
Donor antigens can cause an immune rejection response in the recipient.