Immunology

Question 1

Skin provides a barrier and front line defence between us and what?

Answer 1

Pathogens, chemical insults and physical trauma

Question 2

Factors that contribute to the skin as an immunological system

Answer 2

Structure
Cell types
Cytokines, chemokines, eicosanoids and antimicrobial peptides
Genetics

Question 3

How does the structure of the skin contribute to the skin as an immunological system?

Answer 3

Has a keratin layer and stratification

Question 4

Function of cytokines

Answer 4

Proteins which encourage migration between cells

Question 5

Function of chemokines

Answer 5

Attract migration of cells

Question 6

What happens to an infection in a normal immune response?

Answer 6

It is controlled

Question 7

Hypersensitivity

Answer 7

Overreaction to antigen

Question 8

Immunodeficiency - is the infection controlled?

Answer 8

Infection not controlled and tumours may arise

Question 9

Autoimmunity

Answer 9

Reaction to host tissue causing chronic inflammation

Question 10

Stratum corneum

Answer 10

Keratin layer - formed by terminal differentiation of keratinocytes to corneocytes

Question 11

Important structural proteins in the stratum corneum

Answer 11

Fillagrin, involucrin, keratin

Question 12

Functions of keratin in the epidermis

Answer 12

Sense pathogens via cell surface receptors and help mediate an immune response
Produce antimicrobial peptides that directly kill pathogens
Produce cytokines and chemokines

Question 13

How can keratinocytes be activated?

Answer 13

UV light and sensitizers

Question 14

Main skin resident immune cell

Answer 14

Langerhans cells

Question 15

Birbeck granule

Answer 15

Tennis racket shaped characterisation of the antigen presenting cells Langerhans cells

Question 16

Function of Langerhans cells

Answer 16

Process lipid antigen and microbial fragments and present them to effector T cells
Help activate T cells

Question 17

What type of T cells are mainly found in the epidermis?

Answer 17

CD8+ T cells

Question 18

What type of T cells are mainly found in the dermis?

Answer 18

CD4+ T cells and CD8+ T cells

Question 19

CD4+ T cells associated with inflammation

Answer 19

TH1 (psoriasis), TH2 (atopic dermatitis) and TH17 (psoriasis and atopic dermatitis)

Question 20

Where are T cells produced and sensitised?

Answer 20

Produced in bone marrow, sensitised in the thymus

Question 21

What does antigen recognition and T cell activation involve interaction between?

Answer 21

T cell receptor and major histocompatibility complex, enhanced by co-receptors

Question 22

2 co-receptors in interaction between T cell receptor and major histocompatibility complex

Answer 22

CD4+ helper T cells and CD8+ cytotoxic T cells

Question 23

Function of TH1

Answer 23

Activate macrophages to destroy microorganisms

Question 24

Function of TH2

Answer 24

Help B cells to make antibodies

Question 25

Function of CD8+ cytotoxic T cells

Answer 25

Kill infected cells directly

Question 26

Dendritic cells found in the dermis

Answer 26

Dermis dendritic cell and plasmacytoid dendritic cell

Question 27

What is produced by plasmacytoid dendritic cell?

Answer 27

IFN-alpha

Question 28

True or false: plasmacytoid dendritic cells are found in healthy skin

Answer 28

False - they are found in diseased skin

Question 29

What transmits information from dendritic cells to T and B cells?

Answer 29

Antigen presenting cells

Question 30

True or false: macrophages, neutrophils and mast cells are found in the dermis

Answer 30

True

Question 31

Where is the major histocompatibility complex found?

Answer 31

Chromosome 6

Question 32

Class I histocompatibility complex: - Which cells is it present on? - Which T cells does it present the antigen to? - What type of antigen does it present? - What can it detect?

Answer 32

Present on almost all cells Presents antigen to cytotoxic T cells Presents androgynous antigen Can detect intracellular antigens

Question 33

Class II histocompatibility complex: - Which cells is it present on? - Which T cells does it present the antigen to? - What type of antigen does it present?

Answer 33

Present on antigen presenting cells Presents antigen to helper T cells Presents exogenous antigens

Question 34

True or false: the major histocompatibility complex is involved in immunological recognition and transplant rejection

Answer 34

True

Question 35

Examples of skin conditions associated with inappropriate immune responses/inflammation

Answer 35

``` Psoriasis Atopic dermatitis Bullous pemphigoid Contact dermatitis Morphea/systemic sclerosis Urticaria SLE Skin infections Skin tumours ```

Question 36

Which CD4 cells make IL-17?

Answer 36

TH1 and TH17

Question 37

What things can lead to autoimmunity?

Answer 37

``` Lymphocyte abnormalities Intercell communication Genetic predisposition Anatomic alterations Hormonal influence Infections ```

Question 38

Examples of skin conditions that are autoimmune

Answer 38

Psoriasis, vitiligo and systemic lupus erythematosus

Question 39

Primary immunodeficiency is __ and secondary immunodeficiency is __ (acquired and genetic)

Answer 39

Primary immunodeficiency is genetic | Secondary immunodeficiency is acquired

Question 40

Causes of secondary immunodeficiency

Answer 40

``` AIDS Malignancy Ageing Diabetes Renal malfunction Burns Alcoholic cirrhosis Malnutrition ```

Question 41

Type I hypersensitivity is __ mediated

Answer 41

Antibody - IgE

Question 42

Describe type I hypersensitivity - early exposure and later exposure

Answer 42

Early exposure to antigen causes IgE production, which binds to FcεR1 receptor on mast cells. Later exposure causes rapid cross-linking of the receptors, signal transduction and degranulation of the mast cell

Question 43

Type II and type III hypersensitivity reactions are __ mediated

Answer 43

Antibody - IgG and IgM

Question 44

When are type II hypersensitivity mechanisms important?

Answer 44

Autoimmunity and transplantation e.g. haemolytic disease of the newborn and blood transfusion recipients

Question 45

Skin testing in type III hypersensitivity reaction leads to what?

Answer 45

An Arthus reaction

Question 46

Type IV hypersensitivity is __ mediated

Answer 46

T cell

Question 47

Describe type IV hypersensitivity reactions

Answer 47

Delayed type hypersensitivity is based on T-cell mediated response, which then recruits other cells to the site and peaks 24-48 hours after contact with antigen

Question 48

Factors that can affect skin immune response

Answer 48

Organ transplant, UV, ageing

Question 49

How does organ transplant affect the skin immune response?

Answer 49

Immunosuppression

Question 50

How does UV affect the skin immune response?

Answer 50

Immunosuppression | Affects the structure of the skin

Question 51

How does ageing affect the skin immune response?

Answer 51

Changes in skin structure Decreased ability to detect malignant cells Decreased ability to detect antigen infection risk Decreased ability to distinguish self from non-self - autoimmunity