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103T2- Formation, composition, function and disorders of the blood > WBC's > Flashcards

Flashcards in WBC's Deck (16):

Describe the cell lineage that produces neutrophils and monocytes

Self renewing stem cell

Pluripotent stem cell

Myeloid progenitor

Granulocyte-monocyte CFU (colony forming units)

Neutrophils, Monocytes


State 5 cells the form part of the immune system





Auxillary cells


What are natural killer cells?

How do mast cells differ?

Large granular lymphocytes
They make up around 5% of somatic lymphocytes
They do not have specific receptors

Mast cells have granules but are not granulocytes


What are mast cells and how do they function?

Found in tissues not blood- prominent in mucosal and epithelial tissues
Release substances that affect vascular permeability (histamine)
Express FcεRI (binds IgE)
Differentiation and maturation of mast cells occurs in tissues


What are basophils and how do they function?
What do they look like?

Lobed nuclei and heavily granulated cytoplasm
Non-phagocytic: they function by releasing pharmacologically active substances from cytoplasmic granules
They circulate in blood and are recruited to sites of allergic reaction or ectoparasite infection

Express FcεRI (binds IgE)- when activated causes degranulation of effector mediators (inc. histamine, IL-3 and IL-4)


What are eosinophils and how do they function?
What do they look like?

Bilobed nuclei and granulated cytoplasm (freckled Sun)
Motile phagocytic cells that can migrate from the blood to tissues
Defence against parasites
Majority found in tissues

Function by
1. Releasing highly toxic granule proteins and free radicals to kill parasites and tissue damage in allergic reactions

2. Synthesis and release prostaglandins, leukotrienes and cytokines in order to amplify inflammatory response by activating epithelial cells


What are neutrophils (polymorphonuclear cells) and how do they function?
What do they look like?

Multiblobed nucleus
Found in the blood (60% of circulation leukocytes)
Rapidly recruited to sites of inflammation (1st to arrive)
Short lifespan
Secrete myeloperoxidase which release hypochlorous acid, and ROS which release oxygen free radicals to damage microorganisms.


What are monocytes and how do they function?
What do they look like?

Kidney shaped nucleus
They are precursors to macrophages known as "blood bones phagocytes"
Reservoir of monocytes in spleen, in blood stream they enlarge
Migrate intro tissues approximately 8 hours after release from bones


What are macrophages?

Mature monocytes found in tissues. They are TISSUE SPECIFIC

5-10x larger than monocytes and contain organelles.


Describe the three processes that occur in atherogenesis that lead to atherosclerosis

1. Dysregulation of lipid (cholesterol) metabolism
2. Endothelial cell dysfunction
3. Inflammation as in a response of vascularised tissue to infections & damaged tissue characterised by pain, redness, swelling, heat and loss of function


How does acute inflammation differ to chronic ?

An acute event is the initial event and rapid response
It lasts hours/days
Predominantly mediated by neutrophils and resolves once stimulus is removed

Chronic inflammation lasts weeks/months
Predominantly mediated by mononuclear cells (macrophages, lymphocytes)
Leads to tissue destruction
Attemps to heal (fibrosis)


Outline the process of inflammation

1. Blood vessels dilate and become more permeable
2. Circulating leukocytes migrate into tissues
3. Leukocytes are activated
4. Activated leukocytes destroy microbes and unwanted material


What are cytokines and how do they differ to

MCP1 is an important monocyte chemokine. What does it do?

Low weight proteins/ glycoproteins
Messenger molecules secreted by WBC's
Local response
Involved in development of immune effector cells

Chemokines are a type of cytokine that induce chemotaxis by acting as an attractant for monocytes and neutrophils.

causes adhering monocytes to cross endothelium and lodge in the intima


Cell adhesion to endothelium by circulating cells can occur via two pathways, initial contact and tight adhesions. Outline the two

Adhesion via initial contact involves P-selectin and E-Selectin on endothelium which is recognised by oligosaccharides on leukocytes.

Adhesion via tight junctions involves intercellular adhesion molecules (ICAMs) on the endothelium recognising INTEGRIN on leukocytes.


What is the effect of activated platelets on monocytes?

Adherent/activated platelets can recruit and inflame monocytes


Consider the following pattern recognition receptors. Suggest a ligand for each.

Macrophage mannose receptors
Scavenger receptors
Toll like receptors

Conserved carbohydrate structures

Anionic polymers, acetylated and oxidised LDL