Monday - Diebel - Immunology of skin

Question 1

TLR 4 recognizes what?

Answer 1

Lipopolysaccharide (LPS) (Gram neg.)

Question 2

TLR 9 & 3 recognize what?

Answer 2

Unmethylated viral DNA

Question 3

What do MHC class II antibodies do?

Answer 3

They are used by dendritic cells to hold on to bacterial proteins that they “caught.”

These proteins are then presented to CD4 T-cells.

Question 4

What changes TH0 CD4+ T-cells into:
TH1
TH2

What stops the change into:
TH1
TH2

Answer 4

IL - 12 changes them into TH1
IL - 4 changes them into TH2

INF gamma stops TH0 –> TH2
IL - 4 stops TH0 –> TH1

Question 5

What do TH1 CD4+ T-cells produce?

Answer 5

INF gamma, IL - 2, TNF beta (proinflam).

Question 6

What do TH2 CD4+ T-cells produce? What do they do?

Answer 6

IL - 4, IL - 5. activate eosinofils and mast cells; force class switch antibodies to IgE

Question 7

IgE. Where is it produced? What does it cause? What receptors and what cells are they found on when they are working/overworking?

Answer 7

By B cells in response to TH 2 CD4+ T-cells
Type 1 hypersensitivity, or an allergic reaction.
Found on Fc epsilon receptors on mast cells.

Question 8

Type II immune hypersensitivity

Answer 8

Occur when IgG or IgM antibodies are produced against surface antigens on cells of the body. These antibodies can trigger reactions either by activation compliment or by facilitating the binding of natural killer cells.

Question 9

Type III immune hypersensitivity

Answer 9

When there are too many immune complexes that are not getting cleared by macrophages or other cells of the reticuloendothelial system.

Question 10

Type IV immune hypersensitivity and examples

Answer 10

Delayed hypersensitivity that is caused by cells, not antibodies. Usually it’s specific T cells. (NOT IgE)

Examples: Tuberculosis
leprosy
schistosomiasis
sarcoidosis
crohn's disease

Question 11

Hapten

Answer 11

A small particle <1kDa that binds to protein and antagonizes MHC II T-cells, causes Type IV hypersensitivity. Lipophilic, can enter through the dermis.

Question 12

Three variants of type IV hypersensitivity

Answer 12

Contact (haptens touching the skin),

tuberculin type (induced by CD4 T-cells in response to soluble antigens that may come from infectious agents)

Granulomatous (most important type, persistence of antigen leads to chronic t cell activation via TNF. Macrophages differentiate into epithelioid cells and fuse to form giant cells.)

Question 13

What are keratinocyes? How do they affect the immune response?

Answer 13

Providers of the structural integrity of the epidermis. They can produce cytokines such as
TNF, IL-1, GM-CSF - activates DCs
IL-3 - activates DCs and co-stimulates T cell proliferative responses. Recruits mast cells to induce secretion of TGF-beta (turns off TH1)