Molecules Produced by the Immune System Flashcards
List the three leukocytes with granules in their cytoplasm.
Neutrophils
Eosinophils
Basophils
What do neutrophil granules contain?
5
Defensins
Lysozyme
Myeloperoxidase
NADPH
Oxidase
What do the chemicals present in neutrophil granules do?
2
They kill bacteria by lysis of their cell walls
They also kill bacteria by producing reactive oxygen species
Comment on the granules in both eosinophils and basophils.
They contain toxic granules that are released from the cell
List some of the chemicals present in the granules of eosinophils and basophils.
(7)
Enzymes
Reactive oxygen species
Leukotrienes
Prostaglandins
Cytokines
Histamine
Heparin
What is leukotrienes?
It is a pro-inflammatory molecule
What is prostaglandins?
Its a pro-inflammatory molecule
What does histamine do?
It causes vasodilation and smooth muscle contraction (it causes inflammation)
What does heparin do?
Its an anti-coagulant that causes tissues to swell
What do eosinophils release their granules in response to?
Large, extracellular invaders like parasites
Where do cytokines get their name?
3
‘Cyt’ meaning cell
‘kine’ coming from kinesis - i.e. moving
They were named first because they were though to encourage white cells to move
What are cytokines?
They are protein molecules secreted by cells of the immune system
How do cytokines work?
They bind to receptors on the target cells and initiate signalling cascades that ultimately alters gene expression
Give four effects that cytokines can have.
Proliferation
Differentiation
Activation
Secretion
What is the main difference between cytokines and hormones?
Hormones are usually made by an organ while cytokines can be made by many different immune cells
Explain how cytokines can work in an autocrine factor.
The cells can produce the cytokine it is affected by
Explain cytokines using Type 1 interferons as an example.
4
Virus infected cell
Infected cell releases interferon
Interferon binds to nearby cells
Cells stimulated by interferon make antiviral proteins that prevent viral replication
What is an interleukin?
A cytokine from one white blood cell to another white blood cell
What does interleukin 1 do?
It can tell your brain to increase body temperature and to cause inflammation
List the four things interferon causes in the target cell.
Cells activate factors that interfere with viral replication
Cells produce RNase enzymes
Cells downregulate protein translation
Cells upregulate pro-apoptotic proteins
What is a cytokine storm?
When way too many cytokines are produced in response to infection
Where do interferons get their name?
They were named as they were first known to interfere with viruses
What happens when cells upregulate pro-apoptotic proteins?
Apoptosis occurs
Organised/planned death
What are complement proteins?
5
A collection of over 30 proteins found in the bloodstream
Produced during inflammation
Some cause opsonization
Some cause lysis
Some cause inflammation
Where are complement proteins produced?
4
Most produced in the liver
Monocytes
Macrophages
Epithelial cells
What are the three functions of complement proteins?
Opsonization
Inflammation
Lysis
What is opsonization?
The marking of pathogens for uptake by phagocytes
What is inflammation?
Activated complement proteins cause swelling, vascular permeability, contraction of smooth muscle and degranulation of basophils and mast cells
How are complement proteins used in inflammation?
3
Mast cells release their granules to fight infection
Activated complement components bind to receptors on mast cells and basophils
This causes them to release chemicals including histamine (degranulation)
What is the endpoint of complement activation?
The formation of the membrane attack complex (MAC)
What does MAC stand for?
Membrane attack complex
What does the membrane attack complex do?
3
It makes a pore in the bacterial surface
this allows water to enter the cell
The combination of multiple pores formed and the stress of water influx causes the cell to lyse
What type of cells produce inflammatory granules?
3
Eosinophils
Basophils
Neutrophils
What type of cells produce type 1 interferons?
All nucleated cells infected with viruses
What type of cells produce complement?
3
Hepatocytes
Macrophages
Epithelial cells
