Skin Immunology

Question 1

What are the differences between innaate and adaptive immunity?

Answer 1

innate is non-specific and has no memory whereas adaptive has memory and is highly specific

Question 2

What is the keratin layer also known as?

Answer 2

the stratum corneum

Question 3

what are 3 important structural proteins found in the keratin layer and epidermis?

Answer 3

filaggrin; involucrin and keratin

Question 4

How do keratinocytes sense pathogens?

Answer 4

via cell surface receptors

Question 5

What do keratinocytes produce that can directly kill pathogens?

Answer 5

antimicrobial peptides (AMPs)

Question 6

What is the main skin resident immune cell?

Answer 6

Langerhan cells

Question 7

What cell do Langerhan cells present antigen fragments to?

Answer 7

effector T cells

Question 8

What type of T cell is found in the epidermis mainly?

Answer 8

CD8+ T cells

Question 9

What T cells are found in the dermis?

Answer 9

both CD4+ and CD8+ as well as NK cells

Question 10

What types of helper T cell are associated with psoriasis?

Answer 10

Th1 and Th17

Question 11

What types of helper T cell is associated with atopic dermatitis?

Answer 11

Th2 and Th17

Question 12

What is the difference between Th1 and Th2?

Answer 12

Th1 activate macrophages to destroy micoorganisms whereas Th2 help B cells to make Ab. Thye produce different cytokines

Question 13

What are CD8+ important for protection against?

Answer 13

viruses and cancer

Question 14

Where are T cells sensitised?

Answer 14

thymus (hence the name)

Question 15

What are the types of dendritic cell found in the dermis?

Answer 15

dermal DC and plasmacytoid DC

Question 16

What are the dermal DCs involved in?

Answer 16

Ag presenting and secreting cyto/chemokines

Question 17

what do plasmacytoid DCs do?

Answer 17

produces IFNa

Question 18

What chromosome contains the gene for MHC?

Answer 18

chromosome 6

Question 19

What is the difference between MHC class 1 and 2?

Answer 19

Class 1 is found on almost all cells and presents endogenous Ag to CD8+. Class 2 is found on APC and presents exogenous Ag to helper T cells

Question 20

Descrivbe the immunopathogenesis of psoriasis.

Answer 20

Keratinocytes undergo stress which causes them to release factors stimulating the plasmacytoids to present to Th1 nad Th17 helper T cels. T cells are attracted to dermis by chemokines and there stimulate KC proliferation, AMP release and neutrophil- attracting chemokines. Dermal fibroblasts then become involved and release KC and epidermal growth factors.

Question 21

What does filaggrin do?

Answer 21

mother natures moisturiser- holds onto water molecules

Question 22

How is filaggrin involved in atopic eczema?

Answer 22

mutations in the filggrin gene is associated with sever/early onset disease

Question 23

In atopic eczema there is a defective skin barrier, what does this lead to?

Answer 23

access/sensitisation to allergen and promotes colonisation by microbes

Question 24

What is type 2 hypersensitivity?

Answer 24

cytotoxic mediated. IgM or IgG antibody binds to cell surface antigen.

Question 25

What is type 3 hypersensitivity?

Answer 25

immune complex mediated. immune complexes are despoited in small vessels activating complement etc.

Question 26

What investigations are done for allergies?

Answer 26

spefici IgE; skin prick; challenge test; serum mast cell tryptase level (only during anaphylaxis)

Question 27

When is a challenge test done?

Answer 27

Only if the skin prick test in negative

Question 28

What type of hypersensitvity is allergic contact dermatitis caused by>

Answer 28

type 4

Question 29

What is irritant contact dermatitis?

Answer 29

contact with agents that abrade, irritate and traumatize the skin directly. Non-immunological process