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Flashcards in Immunology Deck (40):
1

What factors contribute to the skin as an immune system

Structure - keratin layer and stratification
Cells - immune cells and keratinocytes
Cytokines, chemokines etc
Genetics

2

What is autoimmunity

When there is a reaction to host tissue
Leads to chronic inflammation

3

What can activate keratinocytes

UV light
Sensitisers - such as in allergic contact dermatitis

4

How do Langerhans cells trigger the immune response

The process antigens and migrate away from the epidermis to the lymph system to present them to T cells

5

What do Birbeck granules look like

Tennis rackets

6

What T cells are found in the epidermis

CD8+

7

What T cells are found in the dermis

CD4+ and CD8+

8

Where are T cells produces

Bone marrow

9

How does T cell activation and antigen recognition occur

Through interaction with the T cell receptor (TCR) and the Major Histocompatibility Complex (MHC)

10

Describe the function of Mast cells

Effectors of the IgE mediated response - allergy
IgE binding causes activation of mast cells and release of inflammatory mediators
The degranulate and release many mediators such as histamine, interleukins and TNF

11

What are MHC proteins

An identity tag protein that sticks out of every cell and allows the body to identify it as self
Can also show which proteins are present in the cell
If a cell lacks MHC it is attacked by the immune system

12

Describe MHC class 1 proteins

Found on almost all cells
Present antigens to cytotoxic T cells
Present endogenous antigens

13

Describe MHC class 2 proteins

Found on antigens presenting cells - B cells and macrophages
Present to Th cells
Present exogenous antigen

14

List 4 conditions that are associated with inappropriate immune responses

Psoriasis
Atopic and contact dermatitis
Bullous pemphigoid
Urticaria

15

List some features of autoimmunity

Lymphocyte abnormality
Genetic predisposition
Hormonal influence
Anatomical alteration

16

Which skin conditions are autoimmune

Vitiligo - melanocytes attacked by T cells
Psoriasis
SLE - autoantibodies are formed for your own DNA

17

What is a primary immunodeficiency

One of genetic causes - inherited defect
Can be specific or non-specific

18

What is a secondary immunodeficiency

One that is acquired
E.g. AIDS, Ageing, cancer, malnutrition, diabetes

19

What mediates a Type I hypersensitivity reactions

IgE antibodies

20

Describe how type I hypersensitivity begins

Early exposure to the antigen causes the production of IgE
This binds to receptors on mast cells
On second exposure the receptors are rapidly activated and the mast cell degranulates - causing the allergic reaction

21

What mediates type II and III hypersensitivity reactions

IgG and IgM antibodies

22

Where is type II hypersensitivity significant

Autoimmunity and transplantation
Haemolytic disease of the newborn
Blood transfusion

23

What mediates a type IV hypersensitivity reaction

Th1 cells
They recruit other cells to the site, hence the delayed response

24

Which factors affect the skins immune response

Organ transplants - immunosuppressed
UV - damages structure
Ageing - change in structure, decreased effectiveness of immune system

25

What is the definition of hypersensitivity

Immune response that causes collateral damage to self
Exaggerated immune response

26

What is an allergy

Hypersensitivity disorder of the immune system
A persons immune system reacts to normally harmless substances

27

Allergy is declining in the UK true/false

False
It is on the increase

28

Describe a type 1 allergy

Immediate reaction - within minutes to 2 hours
Consistent reaction with every exposure

29

What is the clinical presentation of an allergy

Urticaria - itchy rash
Angioedema
Wheezing - asthma
Anaphylaxis

30

Describe urticaria

A very itchy rash
Forms hives or weals
Usually appears within one hour of allergen exposure and lasts a few hours

31

What is angioedema

localised swelling of mucous membrane or subcutaneous tissue
Face and lips

32

What is anaphylaxis

Life-threatening hypersensitivity reaction
Characterised by rapidly developing issues
Involves the airways closing, due to oedema, bronchospasm, hypotension, tachycardia etc

33

How can you investigate allergy

HISTORY!!
IgE blood test
Skin prick test
Patch test - for contact
Challenge test
Check serum mast cell tryptase levels during anaphylaxis

34

What is the skin prick test

Introduce allergen via small needle in the skin
Cheap and quick results
Good specificity and sensitive

35

What is the challenge test

The patient is directly exposed to the allergen
e.g. wear latex gloves or eat peanut butter
Only done in clinical setting if anaphylaxis risk is low

36

What is the management of allergy

Allergen avoidance
Education
May wear alert bracelet
Step 1 - anti-histamine
Step 2 - corticosteroids
Step 3 - epi-pen

37

What are non-allergic reactions

Non IgE mediated
Mast cell granulation is directly caused - e.g. by drugs
Can be metabolic - lactose
Can be caused by toxins
Coeliac disease

38

Describe type IV hypersensitivity

Delayed reaction - 24-48 hours after exposure
Antigen specific
mediated by T cells
often a contact dermatitis

39

How do you test for allergic contact dermatitis

Patch test
Common allergens are places into small discs and stuck to the back
Then left for 48 hours and taken off
Assess reaction after 48 and 96 hours to look for allergic reaction
Tells you which allergen is the cause

40

What is irritant contact dermatitis

Not an immunological process
Contact with irritant agents causes skin irritation
Doesn't need previous sensitisation
Examples: Nappy rash (urine) and lip lick dermatitis (saliva)