White blood cells Flashcards Preview

Module 103, Theme 2: Formation, composition, function and disorders of the blood. > White blood cells > Flashcards

Flashcards in White blood cells Deck (31)
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1

Lymphocytes

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

2

Phagocytes

Includes:
Mononuclear phagocyte
Neutrophil
Eosinophil

Part of the innate immune system.

Mononuclear phagocytes release cytokines and activates complement pathways.

3

Mast cells

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.

4

Axillary cells

Includes:
Basophils
Mast cells
Platelets

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

5

Number of neutrophils per mm3

7.3 x 10^3

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

6

Basophils

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.

7

Eosinophils

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.

8

Toxin in the large granules of eosinophils

Ribonuclease- antiviral.

Cationic protein- apoptosis.

Peroxidase- reactive oxygen species

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

9

Products synthesised by eosinophils which amplify inflammatory responses

Prostaglandins

Leukotrienes

Cytokines

10

Neutrophils

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

11

Monocytes

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.

12

Macrophages

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

13

Myeloperoxidase

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.

14

What wbc main increase in bacterial infection

Neutrophils

Monocytes when infection is chronic.

15

Main wbc involved in viral infections

Mainly lymphocytes

Monocytes also involved

16

Main wbc in parasitic infections

Eosinophils

Mast cells also activated

17

Main wbc involved in fungal infections

Monocytes

18

Main Wbcs involved in allergic reactins

Basophils

Mast cells

Eosinophils- when chronic.

19

Cytokines

Low molecular weight regulatory proteins that act as chemical messengers.

Generally act via paracrine signalling.

20

Chemokines

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

21

MCP-1

Monocyte chemotactic protein-1

Chemokine that attracts monocytes.

22

Initial contact of leukocytes to the endothelium

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

This forms a temporary attraction between the cells.

23

Tight contact of leukocytes to the endothelium

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

24

LFA-1

Lymphocyte function-associated antigen-1

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

25

VLA-1

Very late antigen-1

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

26

VCAM-1

An adhesion molecule on endothelium cells and found in atheromas-

They bind to monocytes and lymphocytes.

27

Cytokines released from activated macrophages.

IL-1 beta

TNF- alpha

IL-6

28

Macrophage mannose receptor

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

These ligands activate the macrophage to undergo phagocytosis.

29

Scavenger receptors

A PRR that recognises:
- Anionic polymers
- Acetylated and oxidised LDL

Recognition of these ligands lead to phagocytosis.

30

Chronic vs acute inflammation

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.