Bacteriology

Question 1

What forms the keratin layer?

Answer 1

terminal differentiation of keratinocytes to corneocytes

Question 2

What do keratinocytes produce, and what does the produce do?

Answer 2

antimicrobial peptides (AMPs) that directly kill pathogens

Question 3

What else do keratinocytes produce?

Answer 3

cytokines and chemokines

Question 4

Describe Langerhans cells

Answer 4

a type of dendritic cell that intersperse with keratinocytes in the epidermis
Main skin resident immune cell
Antigen presenting cells (APC), characterised by Birbeck ganule.

Question 5

What do Langerhans process?

Answer 5

Lipid Ag and ,icrobial fragments and present them to effector T cells

Question 6

Where are CD8+ T cells found?

Answer 6

mainly epidermis

Question 7

CD4+ and CD8+T cells are found where?

Answer 7

dermis

Question 8

What disease is CD4+TH cells associated with?

Answer 8

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

Question 9

Where are T cells (a) produced and (b) sensitised?

Answer 9

(a) bone marrow

(b) thymus

Question 10

Dermal DC cells are involved in…?

Answer 10

secreting cyto/chemokines

Question 11

Mast cells are involved in what allergy response?

Answer 11

IgE - mediated immune response

Question 12

Describe the Major Histocompatibility Complex on chromosome 6 (class 1 )

Answer 12

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

Question 13

Describe the Major Histocompatibility Complex on chromosome 6 (class 1 ) (class 2)

Answer 13

Found on APC (B cells, macrophages)
Present to TH cells
Present exogenous Ag

Question 14

What gene mutation can cause eczema?

Answer 14

Fillagrin gene is assoc. with early/severe onset disease

Question 15

Describe a type 1 hypersensitivity reaction

Answer 15

IgE mediated,
igE binds to FCER1 on mast cells,
rapid repsonse = wheal and flare
Late response = cellular infiltration, nodule

Question 16

Describe type 2 and 3 hypersensitivity

Answer 16

IgG and IgM mediated

Skin testing leads to Arthus reaction

Question 17

Describe Type 4 hypersensitivity

Answer 17

TH1 mediated,
Tuberculin reaction, contact allergy,
Peaks at 24-48 hrs after contact

Question 18

What cells are in the epidermis?

Answer 18

keratinocytes
langerhans cells
T cells (esp CD8+)
Melanocytes

Question 19

What cells are in the dermis?

Answer 19

Dendritic cells
Macrophages
T cells (CD4+ & CD8+)
Natural killer cells
Fibroblasts
Lymph/vasculature (transport/access)