L5 Leucocytes and Inflammation Flashcards
(22 cards)
What is haematopoeisis?
production of blood cells
What is leucopoeisis?
production of leucocytes
What happens during haematopoeisis?
Increasing specialisation (commitment) -Decreasing plasticity
What are the two major leucocyte lineages?
Lymphoid (Lymphocytes) – small, bland-looking cells
Myeloid – larger cells; most have prominent cytoplasmic granules and are called granulocytes
What is the activated function of macrophage?
Phagocytosis and activation of bactericidal mechanisms
Antigen presentation
What is the activated function of dendritic cells?
Antigen uptake in peripheral sites
Antigen presentation in lymph nodes
What is the activated function of neutrophils?
Phagocytosis and activation of bactericidal mechanisms
What is the activated function of eosinophils?
Killing antibody coated parasites
What is the activated function of mast cells?
Release granules containing histamine and other active agents
Lymphoid lineage
Small, bland-looking cells
All look similar by basic light microscopy
Various types with different functions
Special stains needed to resolve
different types on light microscopy
B cells
produce antibodies
Antibodies are proteins that bind to antigens
Particularly important in dealing with extracelllular infections such as bacteria
T cells
Precursors are produced in the bone marrow; complete maturation in the thymus during gestation
CD8 T cells are particularly important in dealing with intracellular infection (viral infection)
CD4 (helper) T cells are needed to direct the activity of the immune system
What is a cytokines?
Cytokines are small proteins released by cells that have an effect on another cell
They are important for communication between cells of the immune system and between immune system cells and other cells and tissues
What is a chemokine?
Very different protein structure
Very different receptors
Mainly involved in temporal and spatial organisation
What are the cardinal features of inflammation?
Pain (Dolor) Heat (Calor) Redness (Rubor) Swelling (Tumor) (Loss of function – added later)
How does inflammation occur?
For many infections, the first step is to breach a barrier such as the skin and enter the tissue
The first cell that will be met is a tissue macrophage
Tissue macrophages will engulf and kill organisms by a process called phagocytosis
What is phagocytosis?
Organism phagocytosed into a phagosome, which then fuses with a lysosome containing digestive enzymes. The organism is killed in this ‘phagolysosome’ by low pH, digestive enzymes, toxic free radicals and hydrogen-oxygen products
Cytokines involved in local inflammation
Tumour necrosis factor alpha (TNF-alpha)
Interleukin-1 (IL-1)
Interleukin-6 (IL-6)
The role of chemokines in local inflammation
Attracting other cells, particularly neutrophils
Acting on blood vessels to cause:
Vasodilation
Increased permeability
Increased adhesion molecules on blood vessel endothelium
What are the outcomes of acute inflammation?
Resolution: insult removed, tissue heals completely
Fibrosis: insult removed, but tissue is scarred
Chronic: insult cannot be removed
Abscess formation
Benefits of inflammation
Amplifies the immune response
Small stimulus creates large local & systemic response
Focuses the immune response
Brings in cells required to contain infection and activate healing process when infection is cleared
Activates the next stages of immunity (B cells/ T cells)
This is the next line of defence, and also how the immune system learns (memory)
Negatives of inflammation
May damage healthy tissue
May be activated inappropriately (without infection)
May be activated in an uncontrolled manner: septic shock
