Immune Function Learning Objectives (L32) Flashcards
What is the role of phagocytes in the non-specific immune response?
Phagocytosing and destroying foreign particles, such as bacteria, viruses, and cellular debris. They are the first line of defence against pathogens in the body
What are the immune cells that make up the specific (or adaptive) immune system?
T-Cells and B-Cells
When a new foreign pathogen enters the body, what is the first response? What cells are involved?
a) Recognition: Immune cells recognize common features of pathogens on their surface. These receptors are like general alarms that trigger a response when they detect potential threats.
b) Activation of innate immune cells + phagocytosis: Upon recognition of pathogens, immune cells such as macrophages, neutrophils, dendritic cells, and natural killer (NK) cells become activated.
When a new foreign pathogen enters the body, innate immune cells react. What do they do to help overcome and neutralise the pathogen?
a) Activated immune cells release chemical signals called cytokines (such as IL1, IL10, TNF-a) which cause chemotaxis, signalling neighbouring immune cells to become more alert and active in their defences (chain reaction).
b) Inflammation (via inflammatory cytokines) cause vasodilation and increased permeability of blood vessels, allowing more immune cells to be recruited to the site of infection.
How are antibodies created after initial exposure to pathogen?
- Antigen presenting cells (dendritic cells and macrophages) detect and engulf pathogens
- They process the pathogen and present them on their cell membrane (MHC molecule)\
- APCs present to T-cells which activate them
- Activated T-cells interact with B-cells which activate them
- Activated B-cells proliferate into plasma cells
- Plasma cells are specialised factories for producing antibodiesW
What do antibodies do to fight an infection (cause by pathogen)?
Specificity:
- Antibodies are specific to the antigen encountered by the B cell in the non-specific immune response.
- Antibodies are released into the bloodstream and tissues to combat the infection.
Pathogen interaction mechanism:
- Antibodies can bind to the surface of pathogens, such as viruses or bacteria, and neutralize their ability to infect host cells.
- Antibodies can mark pathogens for destruction by phagocytes
- They can activate the complement system
What is the cell that is associated with long-term immunity and remembering the initial antigen. Explain this mechanism.
Memory B-Cells. Upon re-exposure to the same antigen, memory B cells quickly respond by proliferating and differentiating into plasma cells, producing a rapid and robust production of antibodies.
What %age of total blood volume is made up of white blood cells?
1%
Where do WBCs typically originate?
Bone marrow
The immune system is like a specialised military team, operating on a ‘seek and destroy’ strategy. Which cells would be synonymous with;
a) the reconnaissance team (provide general surveillance and quick elimination)
b) the intelligence agents (seeking threats based on identifying markers)
c) the specialized operatives (trained and equipped to directly engage and eliminate specific threats)
a) NK cells provide general surveillance and quick elimination of abnormal or infected cells
b) B-cells seek out threats based on identifying markers and produce antibodies to neutralize specific pathogens
c) T-cells directly engage and eliminate specific threats, including infected or abnormal cells
Where are T-cells derived?
Thalmus
Where a B-cells derived?
Bone
What are the %ages of NK, B, and T cells in circulation?
~ 80% T cells
~ 10-15% B cells
~ 5-10% NK cells
What is the configuration of the IgA antibody?
Dimer
Where are IgA antibodies normally found?
Mucous membranes:
– GIT
– Respiratory tract
– Genito-urinary tracts
– Milk & tears
