Immunology

Question 1

What structure of the skin contributes to immune defence?

Answer 1

The keratin layer

Question 2

What is hypersensitivity?

Answer 2

Overreaction to an antigen

Question 3

What is immunodeficiency?

Answer 3

An infection is not controlled

Question 4

What is autoimmunity?

Answer 4

Reaction to host tissue causing chronic inflammation

Question 5

What are some important structural proteins found in the stratum corneum?

Answer 5

Filaggrin, involucrin, keratin

Question 6

What is the immune function of the keratin layer?

Answer 6

Sense pathogens via cell surface receptors and help mediate an immune response

Question 7

What happens to the anti-microbial peptides found in the keratin layer in psoriasis?

Answer 7

They are produced in excess

Question 8

What is the role of cytokines and chemokines released from the keratin layer?

Answer 8

Recruit and regulate cells of the innate and adaptive immune systems

Question 9

What are the main immune cell of the skin? What type of cell is this?

Answer 9

Langerhans cells- a type of dendritic cell

Question 10

What characterises the Langerhans cell?

Answer 10

Birbeck granule

Question 11

Where are CD8+ T cells found?

Answer 11

Mainly in the epidermis but also in the dermis

Question 12

Where are CD4+ T cells found?

Answer 12

In the dermis

Question 13

What are the subtypes of CD4+ T cells which are associated with inflammation?

Answer 13

Th1, Th2, Th17

Question 14

Th1 cells are associated with what condition?

Answer 14

Psoriasis

Question 15

Th2 cells are associated with what condition?

Answer 15

Atopic dermatitis

Question 16

Th17 cells are associated with what condition?

Answer 16

Psoriasis and atopic dermatitis

Question 17

Where are T cells produced? Where are they sensitised?

Answer 17

Produced in the bone marrow and sensitised in the thymus

Question 18

What cells are the basis of cell mediated immunity?

Answer 18

T cells

Question 19

What are CD4+ T cells?

Answer 19

Helper cells

Question 20

What is the function of Th1 cells? What do they release?

Answer 20

They activate macrophages to destroy microorganisms. They release IL2 and interferon gamma.

Question 21

What is the function of Th2 cells? What do they release?

Answer 21

They help B cells make antibodies. They release IL4/5/6

Question 22

What is the function of CD8+ T cells?

Answer 22

These are cytotoxic T cells which directly kill infected cells and are important in defence against viruses and cancer.

Question 23

What is the function of dermal dendritic cells?

Answer 23

Involved in antigen presenting and secretion of cyto/chemokines

Question 24

What is the function of plasmacytoid dendritic cells?

Answer 24

Produce interferon alpha and are found in diseased skin

Question 25

Apart from T cells, what are 3 other types of immune cell which are found in the dermis?

Answer 25

Macrophages, neutrophils and mast cells

Question 26

Mast cells are effectors of immune responses mediated by what? Give examples.

Answer 26

IgE- allergies and parasites

Question 27

Which chromosome are MHC proteins found on?

Answer 27

6

Question 28

On what cells is MHC class I found? What type of antigens do they present and to where?

Answer 28

Found on almost all cells. They present endogenous antigens to cytotoxic T cells.

Question 29

On what cells is MHC class II found? What type of antigens do they present and to where?

Answer 29

Found only on antigen presenting cells. They present exogenous antigens to helper T cells.

Question 30

Psoriatic plaques can be treated by blocking what?

Answer 30

Cytokines

Question 31

What is the immunological cause of atopic eczema?

Answer 31

Impairment of skin barrier function caused by a mutation on the filaggrin gene and decreased anti-microbial peptides in the skin

Question 32

What does the filaggrin break down product act as? What will happen if you don't have this?

Answer 32

It acts as a natural moisturiser- if you don't have this you will develop dry skin (not necessarily eczema)

Question 33

What mediates types II and III hypersensitivity?

Answer 33

IgM and IgG

Question 34

Type II hypersensitivity is of importance when?

Answer 34

Autoimmune disease and transplantation

Question 35

Type III hypersensitivity is often implicated in what common cause of skin problems?

Answer 35

Drug reactions

Question 36

What specific cell is the main mediator of type IV hypersensitivity reactions?

Answer 36

Th1 cells

Question 37

What types of hypersensitivity reactions most commonly involve the skin?

Answer 37

Types I and IV

Question 38

What is urticaria?

Answer 38

Red wheels develop caused by dilated blood vessels and and leakage of fluid into surrounding tissue.

Question 39

What is angioedema?

Answer 39

A deeper reaction than urticaria causing swelling of subcutaneous tissues including mucus membranes

Question 40

What is anaphylaxis? What are some features?

Answer 40

Life threatening reaction- urticaria, angioedema, throat swelling, bronchospasm, hypotension, shock

Question 41

What preformed substances do mast cells produce in response to IgE?

Answer 41

Histamine, tryptase, heparin

Question 42

What synthesised substances do mast cells produce in response to IgE?

Answer 42

Leukotrienes, prostaglandins, cytokines

Question 43

What are three things that secretion of substances from mast cells can cause?

Answer 43

Increased blood flow, contraction of smooth muscle, increased vascular permeability

Question 44

What are some defining features of anaphylaxis?

Answer 44

A: laryngeal oedema, B: bronchospasm, tachypnoea, C: tachycardia, hypotension, potential collapse

Question 45

What are some common features of anaphylaxis?

Answer 45

Urticaria, angioedema, allergic rhinitis, allergic conjunctivitis

Question 46

What is auto-infection?

Answer 46

Infection by a bacteria you are colonised with