Cells of the Immune System Flashcards
What is the immune system composed of?
Cells
Tissues
Organs
Where can cells of the innate immune system be found?
In the blood or in tissues
What are the two main types of blood cells?
Red and white blood cells
What is the scientific name for red blood cells?
Erythrocytes
What is the scientific name for white blood cells?
Leukocytes
What does whole blood consist of?
2
Plasma
Formed elements
What are the formed elements that make up whole blood?
Platelets
White blood cells
Red blood cells
Name the five different types of white blood cells.
Neutrophils
Lymphocytes
Monocytes
Eosinophils
Basophils
List the white blood cells that make up the innate immune system.
(6)
Neutrophils
Eosinophils
Basophils
Monocytes
Dendritic cells
Natural killer cells
What whit blood cells make up the adaptive immune system?
Lymphocytes - B and T
List the three granulocytes - granular wbcs.
Neutrophils
Eosinophils
Basophils
List the agranulocytes - agranular wbcs.
4
Monocytes
Dendritic cells
Natural killer cells
Lymphocytes
What are polymorphonuclear granulocytes?
Granulocytes with multi-lobed nuclei
What is haematopoiesis?
The formation of blood cells
What cells mature in the marrow?
3
Red blood cells
White blood cells
Platelets
What is the most commonly used cell staining technique?
H&E staining
What does the H&E stand for?
Haematoxylin and eosin
What is haematoxylin?
Basic dye that stains acidic structures blue/purple
What is eosin?
An acidic dye that stains basic structures in the cytoplasm red/pink
Which part of the H&E stain dyes blue/purple?
Haematoxylin
Which part of the H&E stain dyes red/pink?
Eosin
How do neutrophils stain with H&E?
They don’t take up either H or E -> they are neutral
Write a note on neutrophils.
8
Polymorphonuclear granulocyte
3-5 lobes
Phagocytic
Most abundant immune cell type in the body
Slightly bigger than rbcs
They make puss yellow - involved in puss formation
Usually the first to arrive at an infection site
Most abundant immune cell - make up 50-70% of all leucocytes
What leukocyte is the most abundant?
Neutrophils
What are the main roles of neutrophils?
2
Phagocytosis - engulfing bacteria
Formation of NETs
What percentage of leukocytes are neutrophils?
50-70% of leukocytes
How can neutrophils indicate infection?
Yellow pus - sputum - indicates infection - as neutrophils are what gives pus this yellow colour
What are NETs?
2
Neutrophil extracellular traps
Sticky webs released by neutrophils to capture bacteria
What is phagocytosis?
The engulfment and destruction of microorganism
How can you tell someone’s sex by looking at their neutrophils?
(2)
A “Barr-body” can be seen in a females neutrophils
This is part of one of the two unused X chromosomes in females
Write a note on eosinophils.
6
polymorphonuclear granulocytes
2-3 lobed nucleus
Slightly larger than neutrophils - so they can fight parasites
Indicators of a parasitic infection
Indicator of allergies
Capable of phagocytosis (can only take in one or two bacterial cells while neutrophils can take in many)
How many lobes do eosinophils have?
2-3 lobes
How do eosinophils stain with H&E?
Their granules are strongly stained with eosin
How do eosinophils fight parasites?
Eosinophils contain toxins in their granules which are released when a parasite is near
What does high levels of eosinophils indicate?
2
Parasitic infection
Allergies
Write a note on basophils.
6
Polymorphonuclear granulocytes
2-3 lobed nucleus
Affinity for haematoxylin/basic dyes
Function unknown
Circulate in blood
Release chemicals that enhance inflammation (including histamine)
Contain heparin, an anticoagulant
How many lobes do basophils have?
2-3 lobes
How do basophils dye with H&E?
Dyed with haematoxylin
What do basophils do?
2
Release chemicals that enhance inflammation (including histamine)
They contain heparin (anticoagulant)
What coagulant is found in basophils?
Heparin
Write a note on monocytes.
7
Found in circulation
Distinctive horseshoe-shaped nucleus
No lobes
Live for months
Phagocytic
Antigen-presenting cell
Agranular cytoplasm
Where are monocytes found?
In circulation
Describe the nucleus of monocytes.
No lobes
Horseshoe shaped
How long do monocytes live?
They live for months
What two things can monocytes do?
Phagocytosis
Antigen presentation
How do monocytes present antigens?
Monocytes engulf foreign materials, break them down and then show peptides to T cells to see if an immune response is activated
Describe the cytoplasm of monocytes.
Agranular
What are monocytes often called?
Scavengers
Write a note on macrophages.
9
Cells derived from blood monocytes
Found in tissues
Their name depends on their location in the body
Name means ‘big eater’ - Voracious phagocytosis
Live for months
Antigen presenting cells
Flattens out and becomes star shaped - form pseudopodia
Can change shape and deform
Has lots of lysosomes - break down of pathogens
What are macrophages often called?
Garbage disposal cells
What cells are often called scavengers?
Monocytes
What cells are often called garbage disposal cells?
Macrophages
What do macrophages do?
3
Search for pathogens between tissues using their pseudopodia and ability to change shape
They phagocytose any pathogens they find - breaking them down with lysosomes
They present peptides that they have broken down to lymphocytes
Write a note on dendritic cells.
5
Motile
Phagocytic
Best antigen present cell
Resemble dendrites of nerve cells
Different names depending on location in the body - e.g. Langerhans cells
How do dendritic cells present antigens?
3
Dendritic cells display NHC molecules which contain peptides from invading organisms on their cell surface
Dendritic cell then moves around to find the right T cell
T cells dock with the dendritic cell and decide on a response
What cell gives rise to macrophages and dendritic cells?
Peripheral blood monocytes
Write a note on Lymphocytes.
6
Two types: T cells and B cells
Part of the acquired immune system
Large, round nucleus
Very little cytoplasm visible
Perfectly round cell with round nucleus
Unable to determine if a B or T lymphocyte using only a microscope
Write a note on T lymphocytes.
3
Killers or Helpers
Killers - tell infected cells to kill themselves by apoptosis
Helper T cells coordinate immune responses - help make antibodies
How do killer T cells make other cells kill themselves?
Cells shrink and keep their contents inside
Write a note on B cells.
B cells become plasma cells which excrete antibodies
How do antibodies prevent covid infections?
Antibodies bind to spike proteins of covid which prevent the virus from binding to normal cells
Write a not on natural killer cells.
4
Large granular lymphocytes
Specialised type of lymphocyte
Attack and kill virus-infected cells and cancerous cells
Not specific - don’t care what type of virus or what type of cancer
How do natural killer cells work?
3
They approach all cells
They feel the surface of the cell
Is there anything there that shouldn’t be? Has the cell been flagged with an antibody?
If so, the natural killer cells cause the cells to kill themselves.
What is the main use of natural killer cells?
They can be used to treat cancers
Write a note on mast cells.
6
Not found in circulation
Immune system “gatekeepers”
Located in the skin, mucosae and connective tissue
Non-motile
Release granules that contain chemicals that enhance inflammation such as histamine
Activated by complement proteins and antibodies
What are mast cells often called?
“gatekeeper cells”
How do mast cells enhance inflammation?
mast cells release their granules that contain chemicals that enhance inflammation such as histamine
How do you remember the order of leukocytes from most abundant to least?
Never Let Monkeys Eat Bananas
Neutrophils Lymphocytes Monocytes Eosinophils Basophils
What percentage of leukocytes are neutrophils?
40-75%
What percentage of leukocytes are eosinophils?
1-6%
What percentage of leukocytes are basophils?
Less than 1%
What percentage of leukocytes are monocytes?
2-10%
What percentage of leukocytes are lymphocytes?
20-50%
What do CD molecules stand for?
Cluster of differentiation molecules
What do immunologists use CD molecules for?
To differentiate between cells
How do immunologists use CD molecules to differentiate between cells?
On the basis that different cells express different molecules on their cell surfaces
How are CD molecules names?
They are named with only a number in the order in which they were found
How many CD molecules are there to date?
371 CD molecules
What CD molecules do T cells express?
CD3
What CD molecules are expressed by natural killer cells?
CD56
What CD molecules are expressed by B cells?
CD20
