Lecture 5: Leucocytes and Inflammation Flashcards
What is the immune system?
A collection of cells, tissues and molecules that mediate protection against infection.
What is haematopoeisis?
Production of blood cells from stem cells that develop increased specialisation and decreased plasticity until they become mature blood
What is lucopoesis?
Production of leucocytes (white blood cells) from a common leucocyte precursor
What is the purpose of lymphoid tissue?
Lymphoid tissues are collections of leucocytes, and serve as meeting points for cells of the immune system.
What are the 2 major leucocyte lineages?
- Lymphoid
2. Myeloid
What immune cells does the lymphoid lineage produce?
Lymphocytes- T cells, B cells and NK cells
What immune cells does the myeloid lineage produce?
Neutrophils, eosinophils, basophils, monocytes, mast cells and macrophages.
What are macrophages?
APCs that are responsible for phagocytosis and activation of bacterial mechanisms
What are dendritic cells?
APCs in the lymph nodes that are responsible for antigen uptake in peripheral sites.
What are neutrophils?
Immune cells responsible for phagocytosis and activation of bacterial mechanisms.
What are eosinophils?
Immune cells responsible for killing antibody-coated particles.
What are basophils?
Immune cells with unknown function, however, participates in phagocytosis and releases histamine
What are mast cells?
Immune cells that release granules containing histamine, etc.
What are the 2 types of T-cells?
CD4+ (T-helper cells)
CD8+ (T-effector cells)
Where are T cells produced?
T-cell precursors are produced in the bone marrow and they complete maturation in the thymus where they undergo somatic hypermutation to become selective
What is the role of CD4+ T cells?
CD4+ (helper) T cells are needed to direct the activity of the immune system
What is the role of CD8+ T cells?
CD8+ (effector) T cells are particularly important in dealing with intracellular infection (viral infection)
What is the role of B cells?
B cells produce antibodies specific to antigen of infection. Adaptive immune response. Particularly important in dealing with extracellular infections such as bacteria.
What is the role of NK cells?
Natural killer cells destroy cells are particularly useful in dealing with intracellular infection and tumours.
How do immune cells communicate with one another?
- Chemokines
- Cytokines
- Cell-cell contact (juxtacrine or contact-dependent signalling)
What are cytokines?
Cytokines are small proteins released by cells that have an effect on another cell and trigger migration of immune cells towards the site of infection.
What are chemokines?
Chemokines are similar to cytokines except they have different protein structures and different receptors. Mainly involved in temporal and spatial organisation.
How do immune cells communicate via cell-to-cell contact?
Immune cells need to be in close proximity and they either make contact or send signals (juxtacrine).
What are the signs of inflammation?
- Pain
- Heat
- Redness
- Swelling
- Loss of function.
What causes inflammation?
- Macrophage migrates to infection site and phagocytoses’ organism.
- Macrophage releases release soluble mediators such as cytokines (eg. TNF-alpha, IL-1, IL-6) and chemokines.
- Soluble mediators promote local inflammation by attracting other immune cells
- Soluble mediators also act on blood vessels to cause vasodilation, increased permeability, and increased adhesion molecules
What causes the redness, heat and swelling during inflammation?
Vasodilation and increased vascular permeability
What causes the pain during inflammation?
• Inflammatory cells migrating to tissue and releasing inflammatory mediators
What are some examples of cytokines?
TNF-alpha, IL-1, and IL-6
What is the role of soluble mediators such as cytokines and chemokines?
- To attract other immune cells to the site of infection
- To act on blood vessels to cause vasodilation, increased permeability, and increased adhesion molecules on blood vessel endothelium.
What does systemic inflammation lead to?
SEPSIS
What are the signs of systemic inflammation (sepsis)?
Fever, fatigue, muscle pain, loss of muscle and fat, and anorexia.
Systemic inflammation also causes damage to healthy tissue (‘bystander damage’)
