White blood cells

Question 1

Lymphocytes

Answer 1

Includes:
B cells
T cells
Large granular lymphocyte (NK cells).

B cells and T cells are antigen specific because of their receptors.

B cells release antibodies.
T cells and NK cells release cytokines.

NK cells are not antigen specific

Question 2

Phagocytes

Answer 2

Includes:
Mononuclear phagocyte
Neutrophil
Eosinophil

Part of the innate immune system.

Mononuclear phagocytes release cytokines and activates complement pathways.

Question 3

Mast cells

Answer 3

Axillary cells ONLY found in the tissue- where they differentiate and mature.

They release granules containing histamine and other active agents- affects vascular permeability.

Expresses FceRI- which binds to IgE, form of opsonisation.

Question 4

Axillary cells

Answer 4

Includes:
Basophils
Mast cells
Platelets

They release inflammatory mediators and are part of the innate immune system.

Question 5

Number of neutrophils per mm3

Answer 5

7.3 x 10^3

This accounts for 50-70% of the total number of leukocytes.

Question 6

Basophils

Answer 6

A type of axillary cell that circulates in the blood and contains:
Lobed nuclei
Heavily granulated cytoplasm

Function:
Does not undergo phagocytosis.

Releases pharmacologically active agents from their granules:

• Histamine
• IL-13
• IL-4

Expresses Fc(e)RI which binds to IgE—> binds to allergens.

Question 7

Eosinophils

Answer 7

A phagocyte that is mainly located in the tissues and contains:

• Bilobed nuclei.
• Granulated cytoplasm- granules release toxin proteins and free radicals.

Function:

• Can migrate from blood to tissue.
• Expresses Fc(e)RI when activated.
• Involved in allergic reactions and release toxins to attack parasites in GI, respiratory and genitourinary tracts.

Question 8

Toxin in the large granules of eosinophils

Answer 8

Ribonuclease- antiviral.

Cationic protein- apoptosis.

Peroxidase- reactive oxygen species

Hypobromous acid (HOBr)- dissociates into hypobromite ion, a strong oxidising agent.

Question 9

Products synthesised by eosinophils which amplify inflammatory responses

Answer 9

Prostaglandins

Leukotrienes

Cytokines

Question 10

Neutrophils

Answer 10

Phagocytes found in the blood contains:
- Myeloperoxidase and reactive oxygen species (ROS)

Function:
- First leukocytes recruited to the sites of infection/ injury.

Has a short lifespan

Question 11

Monocytes

Answer 11

A mononuclear phagocytes that is the premature form of a macrophage.

Features:

• Kidney shaped nucleus.
• Circulate the blood stream and enlarge.
• Reservoir located in the spleen.

Question 12

Macrophages

Answer 12

A mononuclear phagocytes that is tissue specific- differentiated monocyte.

5-10 times larger than monocytes and contains more organelles than them.

Includes:
Alveolar macrophage- lung
Histiocytes- connective tissue
Kupffer cells- liver
Osteoclasts- bone
Microglial cells- brain

Question 13

Myeloperoxidase

Answer 13

An enzyme commonly found in neutrophils which produced hypochlorous acid:

This acid is a strong oxidising agent that kills pathogens, especially bacteria.

It is stored in the granules of neutrophils and since it has a haem pigment it appears green in pus and some mucus.

Question 14

What wbc main increase in bacterial infection

Answer 14

Neutrophils

Monocytes when infection is chronic.

Question 15

Main wbc involved in viral infections

Answer 15

Mainly lymphocytes

Monocytes also involved

Question 16

Main wbc in parasitic infections

Answer 16

Eosinophils

Mast cells also activated

Question 17

Main wbc involved in fungal infections

Answer 17

Monocytes

Question 18

Main Wbcs involved in allergic reactins

Answer 18

Basophils

Mast cells

Eosinophils- when chronic.

Question 19

Cytokines

Answer 19

Low molecular weight regulatory proteins that act as chemical messengers.

Generally act via paracrine signalling.

Question 20

Chemokines

Answer 20

Cytokines which are directly involved in chemokines- attracts monocytes and neutrophils to site of infection.

Question 21

MCP-1

Answer 21

Monocyte chemotactic protein-1

Chemokine that attracts monocytes.

Question 22

Initial contact of leukocytes to the endothelium

Answer 22

P-selectin and E-selectin on endothelium recognise sulfated sialyl-Lewis ^x on leukocytes.

This forms a temporary attraction between the cells.

Question 23

Tight contact of leukocytes to the endothelium

Answer 23

Intracellular adhesion molecules (ICAMs) on the endothelium recognise integrins on leukocytes.

Question 24

LFA-1

Answer 24

Lymphocyte function-associated antigen-1

An integrin that binds to ICAM-1 (CD54): tight adhesion

Question 25

VLA-1

Answer 25

Very late antigen-1

An integrin that binds to VCAM-1 (CD106) in a tight adhesion during chemotaxis.

Question 26

VCAM-1

Answer 26

An adhesion molecule on endothelium cells and found in atheromas-

They bind to monocytes and lymphocytes.

Question 27

Cytokines released from activated macrophages.

Answer 27

IL-1 beta

TNF- alpha

IL-6

Question 28

Macrophage mannose receptor

Answer 28

A pattern recognition receptor on macrophages that recognise conserved carbohydrate structures on pathogens.

These ligands activate the macrophage to undergo phagocytosis.

Question 29

Scavenger receptors

Answer 29

A PRR that recognises:

• Anionic polymers
• Acetylated and oxidised LDL

Recognition of these ligands lead to phagocytosis.

Question 30

Chronic vs acute inflammation

Answer 30

Length- acute is the first rapid response to pathogen. Chronic lasts weeks-months.

Leukocytes involved:
Acute= neutrophils
Chronic= macrophages, lymphocytes

Resolution:
Acute inflammation resolves once stimulus is removed.
Chronic inflammation can cause tissue destruction and lead to fibrotic healing.

Question 31

Overview of inflammation

Answer 31

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