immunology

Question 1

what factors contribute to skin as an immunological system

Answer 1

structure
cell type
cytokines, chemokine, antimicrobial peptides
genetics

Question 2

what is non specific innate immunity

Answer 2

Immediate defence
No memory
Non specific
First line

Question 3

what is specific adaptive immunity

Answer 3

Memory
Highly specific
Tolerance
Self limiting

Question 4

what is hypersensitivity

Answer 4

overreaction to antigen

Question 5

what is autoimmunity

Answer 5

Reaction to host tissue. Autoimmunity is the system of immune responses of an organism against its own healthy cells, tissues and other body normal constituents.

Question 6

how is a keratin layer/epidermis formed

Answer 6

Its a physical barrier formed by terminal differentiation of keratinocytes to corneocytes. Important structural proteins in the keratin layer and epidermis include filaggrin/involucrin/keratin

Question 7

how are keratinocytes activated

Answer 7

by UV (sunlight) and sensitisers (allergic contact dermatitis)

Question 8

what is the function of keratinocytes

Answer 8

Structural and functional cells of the epidermis

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

Produce antimicrobial peptides (AMPs) that can directly kill pathogens

Produce cytokines and chemokines

Question 9

what is the function of langerhans cells in the epidermis

Answer 9

The main skin resident immune cell

Antigen presenting cells characterised by Birbeck granule

• they act as sentinels in the epidermis
• they produce lipid AG and microbial fragments and present them to effector cells
• they help to activate T cells

Question 10

what are the main T cells in the epidermis and dermis

Answer 10

EPIDERMIS
CD8+T cells

DERMIS
CD4+ and CD8+T cells

other subset of T cells are found

Question 11

what CD4+TH cells are associated with inflammation

Answer 11

TH1 = psoriasis 
TH2 = atopic dermatitis 
TH17 = psoriasis and atopic dermatitis

Question 12

what is the function of dendritic cells in the dermis

Answer 12

Dermal DC are involved in Ag presenting and secreting cytoplasms/chemokines

Plasmacytoid DC produce IFNalpha and is found in diseased skin

APCs transmit information to T and B cells

Secrete cytoplasms/chemokines during the inflammatory (immune) response. Chemical signals modulate the immune response and recruit/activate different cell types to the locus

Question 13

what is major histocompatibility complex class 1

Answer 13

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

Question 14

what is major histocompatibility complex class 2

Answer 14

Found of APC (B cells and macrophages)
Present to TH cells
Present exogenous Ag

Question 15

explain Type I hypersensitivity

Answer 15

• Antibody mediated: IgE
• Early exposure to the allergen causes the production of IgE which binds to a receptor on mast cells. Later exposure causes rapid cross linking of the receptors, signal transduction and degranulation of mast cell

Question 16

explain Type II and III hypersensitivity

Answer 16

• Antibody mediated IgG and IgM

- Type II mechanisms important in autoimmunity and transplantation

Question 17

explain type IV hypersensitivity

Answer 17

• Cell mediated THI cell
• Delayed type hypersensitivity is based on a T cell mediated response, which then recruits other cells to site
• peaks at 24-48 hrs after contact with Ag