Inflammation and the Immune System Flashcards
What are the roles of the immune system?
- Prevention of infection:
1. Physical Barriers–e.g. epithelium
2. Innate Immunity–Natural immunity that exists prior to sensitisation–Non-specific phagocytosis
3. Adaptive immunity–Acquired immunity following sensitisation with antigen
————–Highly specific, generation of an immunological memory
What is an antigen?
Protein molecule recognised as foreign against which antibodies generated.
What is an antibody?
Antigen-specific proteins produced by B-Lymphocytes (B-cells) in response to antigen
What are Lymphocytes?
Type of white blood cells:
* B cells and plasma cells
* T cells
* Natural killer cells
What is inflammation?
Physiological response to injury-heat, pain, redness, swelling
What is Hypersensitivity?
Reaction that leads to reproducable symptoms in a susceptible individual
What is an allergy?
Hypersensitivity reaction initiated by immune system
What is the structure of the immune system?
Major lymphoid organs and tissues
(See PP for diagram)
What is the lymphatic system?
Lymph nodes occur at junctions of draining lymph vessels
What is the Spleen?
- The largest lymphoid tissue
- Filters blood-borne pathogens and antigens
- Contains B cells and T cells
What are Antibodies-immunoglobins?
What are the 5 main classes of immunoglobins?
- IgG–monomer
- IgM–Pentamer
- IgA–Dimer
- IgE–Monomer
- IgD–Monomer
Describe the IgG immunoglobin.
- 75% of blood
- Most common, opsonization for phagocytosis
- Also neutralises toxins
- Crosses placenta
- Provides long term immunity (i.e. memory)
Describe the IgM immunoglobin.
- 10% of blood
- First to be made in response to antigen, large molecule
- Antigen receptor of naive B cells
Describe the IgA immunoglobin.
- 15% of blood
- Antigen receptor for B cells
- Found in secretions
- Mucosal immunity- secretory IgA in lumens of gut and respiratory tracts
Describe the IgE immunoglobin.
- < 1% of blood
- Binds to mast cells
- Leads to activation of allergic responses (e.g. asthma)
Describe the IgD immunoglobin.
- < 1% of blood
- Antigen receptor of naive B cells
Why is IgE important?
- Mast cell bound IgE responsiblefor mast cell degranulation in allergy e.g. asthma
- Binds to mast cells through Fc e receptor
- Atopic individuals produce more IgE–correlates with inc susceptibility to asthma, eczema, hay fever.
What is Clonal selection? (B cells)
- When immune system attacked effector cells produce immune response
- But also memory cells produce future response
What is the difference between Primary and secondary response?
Primary:
* First encounter with the organism, either as a disease-causing infection OR preferrably a vaccine
Secondary:
* Subsequent encounter with same organism
* Secondary response is much faster and stronger than primary due to T and B memory lymphocytes
What are the cells of the immune system?
What is adaptive immunity?
- Humoral immunity: Immune response mediated by antibodies and complement
* Mediated by B cells
* Complement - Group of blood proteins that enhance the immune system - Cell-mediated immunity: Immune response mediated by immune cells, e.g. T lymphocytes
What are Antigen presenting cells?
Cells that present antigen to T-cells. They include:
1. Macrophages
2. B cells
3. Dendritic cells
What are Macrophages?
- Engulf and digest a pathogen
- Presents antigen on surface of cell, which is recognised by other immune cells.
- Macrophages are also known as:
1. Alveolar cells–Lungs
2. Kupffer cells–Liver
3. Microglial cells–Brain
4. Osteoclasts–In the bone
5. Mesangial Cells–In the kidney
