Granulocytes

Question 1

What does the buffy coat represent in the haemotocrit?

Answer 1

all the white blood cells present in the blood

Question 2

What are white blood cells?

Answer 2

leukocytes- cells of the immune system involved in protecting the body against both infectious disease and foreign invaders

Question 3

Main difference between red and white blood cells

Answer 3

leukocytes are nucleated

Question 4

Two broadest categories of leukocytes

Answer 4

structure- granulocytes

cell lineage- myeloid cells or lymphoid cells

Question 5

3 types of granulocytes

Answer 5

neutrophils, eosinophils and basophils

Question 6

Defining characteristics of granulocytes

Answer 6

• contain polymorphic nucli
• contain cytoplasmic granules- specific and lysozymes
• spherical in blood plasma, amoeboid in tissues
• terminally differentiated with a life span of a few days
• poorly developed golgi and RER

Question 7

What type of cell are neutrophils?

Answer 7

Polymorphonuclear cells that act as phagocytes

Question 8

Polymorphonuclear definition

Answer 8

nuclei are shaped into 3 lobed segments

Question 9

what does this differentiate between/

Answer 9

mononuclear granulocytes

Question 10

What percentage do neutrophils occupy of the total white blood cell count?

Answer 10

60-65%

Question 11

When are neutrophils produced?

Answer 11

During an acute bacterial infection

Question 12

Two types of granules in neutrophils

Answer 12

azurophilic primary and specific secondary

Question 13

azurophilic function

Answer 13

contain proteases and antibacterial proteins such as myeloperoxidase lysozyme and defensins.

lysosomes fuse with ingested phagosome and secrete toxic chemicals into phagolysosome

Question 14

Function of each of the antibacterial proteins

Answer 14

myeloperoxidase- generates hypochlorite and other agents toxic to bacteria

lysozyme- degrades components of the bacterial cell wall

defensins- small cystseine rich proteins that bind and disrupt the cell membranes of many types of bacteria and microorganisms

Question 15

specific granules function

Answer 15

secrete various ECM degrading enzymes, such collagenases

insert new cell membrane components

Question 16

How are neutrophil numbers increased during an immune response?

Answer 16

increased mobilisation from extensive reserves

increased production from progenitors

Question 17

How do neutrophils act during an immune response?

Answer 17

release chemokines that attract other leukocytes and cytokines

adhere to cell walls and transmigrate by diapedesis to areas of infection

engulf bacteria- lead to collateral damage of host cells

Question 18

What is a form of collateral damage?

Answer 18

apoptotic neutrophils, bacteria, semi-digested material and tissue fluid form a viscous fluid of pus

Question 19

Pus definition

Answer 19

an exudate, typically white-yellow, formed at the site of inflammation during bacterial infection

Question 20

How is pus formed?

Answer 20

during infection, macrophages release cytokines which trigger neutrophils to seek the site of infection by chemotaxis.

There, the neutrophils release granules which destroy the bacteria. As the neutrophils die off from toxins and old age, they are destroyed by macrophages forming viscous pus

Question 21

Example of pus

Answer 21

axillary lymphadenitis- swollen, painful lymph node due to infection

Question 22

Eosinophils general features

Answer 22

generally larger than neutrophils- however only slightly

large ovoid granules- very electron dense

Question 23

Eosinophil locations

Answer 23

lungs and gut

Question 24

What type of cell is it + what controls it?

Answer 24

effector cell

T lymphocytes

Question 25

When are they elevated in blood levels?

Answer 25

tropical parasite infections

chronic allergic reactions- allergic airway disease

Question 26

What is contained within the eosinophil granules?

Answer 26

crystalline core with Major basic proteins, eosinophilic peroxidase and other enzymes

Question 27

Function and structure of major basic proteins

Answer 27

arginine-rich factor- similar structure to lectins

act as a cytotoxin and helminthotoxin in immune hypersensitivity reactions

Question 28

Helminths definition

Answer 28

parasitic worms

Question 29

How do eosinophils work?

Answer 29

passively absorb IgE antibodies, attaches receptors to allow them to recognise specific antigens

can exocytose toxic substances. Secrete eosinophil cationic protein

Question 30

Percentage of eosinophils in buffy coat

Answer 30

1-4%

Question 31

percentage of basophils in buffy coat

Answer 31

less than 1%

Question 32

Granule contents

Answer 32

heparin and other sulfated GAGs

histamine

mediators of inflammation: platelet activating factor, eosinophil chemotactic factor, phospholipase A

Question 33

What are the basophils similar to?

Answer 33

mast cells

Question 34

Structure of basophil nuclei

Answer 34

two lobes- chromatin filaments that connect them are not visible

Question 35

Basophil function

Answer 35

released from bone marrow into the site of the infection

when basophils are injured they release histamine, aids inflammatory response

also released prostaglandins

Rapidly produce interleukins IL4 and IL13 on activation

Question 36

Histamine function

Answer 36

causes dilation and increased permeability of capillaries close to the basophil

increases the blood flow to the site of infection which enables blood clotting

Question 37

What receptors are present? + function of IgE

Answer 37

IgE, IgG, complement and histamine

1. IgE binds to the basophil
2. causes crosslinking of bound IgE and the underlying receptor
3. degranulation occurs- secretes mediators and cytokines

Question 38

How does each granulocyte appear once stained with H&E + why?

Answer 38

neutrophil- deep purple lobed nuclei, pale granules

eosinophil- abundant coarse granules that stain mainly orange due to the major basic proteins, which are greatly basophilic. Bilobed nuclei

basophil- granules stain purple- fewer and larger, more irregularly shaped. May obscure nuclei- deep blue due to GAGs

Question 39

diameters of granulocytes

Answer 39

neutrophil- 12-15μm

eosinophil- 12-17μm

basophil- 14-16μm

Question 40

Lifespan of granulocytes

Answer 40

neutrophil- 1-4 days

eosinophil- 1-2 weeks

basophil-months

Question 41

Chemotaxis definition

Answer 41

movement towards a chemical signal

Question 42

chemotaxis of neutrophils explained

Answer 42

cell surface receptors allow neutrophils to detect chemical gradients of molecules, such as interleukin-8, interferon gamma and more

extend pseudopods wen amorphous in structure to look for antigens

Question 43

Main agranulocyte

Answer 43

monocyte

Question 44

Monocyte definition

Answer 44

Largest type of leukocyte that can differentiate into macrophages and myeloid lineage dendritic cells

Question 45

Structure of monocytes

Answer 45

• amoeboid in apperance
• nongranulated cytoplasm
• unilobar, kidney shaped nuclei
• shelter azurophil granules

Question 46

Appearance when stained with H&E

Answer 46

chromatin stains lighter than in large lymphocytes. unable to see azurophilic granules as they require a very high resolution- however give the cytoplasm a blueish-grey tinge

Question 47

Where are monocytes found?

Answer 47

The blood

Question 48

Where are macrophages found?

Answer 48

tissues

Question 49

Examples of macrophages

Answer 49

Langerhan’s cells in skin

Kupffer cells in liver

Question 50

Different types of macrophage

Answer 50

resident- macrophages present in tissue

monocyte derived- replace the resident macrophages

Question 51

How are resident macrophages replaced?

Answer 51

seeded in development and then replaced by proliferation in tissues

Question 52

macrophage function

Answer 52

• phagocytosis
• remove tissue by releasing enzymes such as collagenase
• allow effective repair
• involved in tissue homeostasis and remodelling