Immunology

Question 1

what are the chemical signals/ molecules in the skin that influence cell behaviour or help target pathogen

Answer 1

cytokines, chemokines, eicosanoids, antimicrobial peptides

Question 2

what is an antigen

Answer 2

any chemical structure (usually a protein/peptide) that can illicit an immune response via an antibody or t cell

Question 3

what is hypersensitivity

Answer 3

overreaction to an antigen

Question 4

what is autoimmunity

Answer 4

reaction to host tissue- chronic inflammation

Question 5

what forms the keratin layer

Answer 5

terminal differential of keratinocytes to corneocytes

Question 6

name three important structural proteins in the keratin layer and epidermis

Answer 6

filaggrin

involucrin

keratin

Question 7

what is the stratum corneum

Answer 7

a.k.a keratin layer

Question 8

what are the 3 main roles of keratinocytes in the epidermis

Answer 8

sense pathogens via cell surface receptors and help mediate an immune repsonse

produce antimicrobial peptides (AMPs) that directly kill pathogens

produce cytokines and chemokines

Question 9

what can activate keratinocytes

Answer 9

UV and sensitisers (e.g. allergic contac dermatitis)

Question 10

what are langerhans cells and where are they in the skin

Answer 10

a dendritic cell (the main skin immune cell) that is interspersed with keratinocytes in the epidermis

Question 11

name the antigen presenting cell in the cell that has birbeck granules

Answer 11

antigen presenting cells

Question 12

what is the role of langerhans

Answer 12

process lipid Ag and microbial fragments and present them to effector T cells- helping to activate them

Question 13

where in the skin are CD8+T cells mostly found

Answer 13

in the epidermis

Question 14

where in the skin are CD4+T and CD8+T found

Answer 14

dermis

Question 15

what inflammation condition is associated with the CD4+TH cell TH1

Answer 15

psoriasis

Question 16

what inflammation condition is associated with the CD4+TH cell TH2

Answer 16

atopic dermatitis

Question 17

what inflammation condition is associated with the CD4+TH cell TH17

Answer 17

psoriasis and atopic dermatitis

Question 18

where are t cells produced and matured (sensitised)

Answer 18

bone marrow

thymus

Question 19

what are t cells the basis of

Answer 19

cell mediated immunity

Question 20

what is the role of CD4+T cells and the roles of the different types

Answer 20

helper t cells- release chemical mediators or signalling molecules such as interleukins and interferons

TH1 activate macrophages to destroy microorganisms (IL2 and IFNy)

TH2 help B cells to make Ab (IL4, IL5, IL6)

Question 21

what is the role of CD8+T cells

Answer 21

cytotoxic T cells- can kill infected cells, viruses and cancer cells directly

Question 22

what connects triggers the immune response when it can not be made

Answer 22

connection between cells to recognise each other involving MHC

Question 23

what are the different types of dendritic cells found in the dermis and their role

Answer 23

dermal DC- Ag presetation and secretion of cyto/chemokines

plasmacytoid DC- produce IFNa, found in diseased skin

Question 24

what is the role of dendritic cells

Answer 24

antigen presenting cells

transmit information to T and B cells

secrete cyto/chemokines during the inflammatory immune response

Question 25

why would neutrophils be in the skin

Answer 25

as circulating leukocytes (neutrophils, basophils, eosinophils) are attracted to tissue by chemokines

Question 26

what is the role of mast cells in the skin

Answer 26

effectors of IgE mediated immune response (allergy), when activated release inflammatory mediators

Question 27

what are the preformed inflammation mediators released by mast cells

Answer 27

TNF, tryptase, chymase, histamine

Question 28

what else can activate mast cells

Answer 28

physical trauma, drugs, micro-organisms

Question 29

what chromosome encodes MHC

Answer 29

chromosome 6

Question 30

what is the role of MCH1 and where is it found

Answer 30

on almost all cells present Ag to cytotoxic T cells present endogenous Ag

Question 31

what is the role of MHC2 and where is it foun

Answer 31

found on antigen presenting cells (B cells, macrophages) present to TH cells present exogenous AG (1= present to cytotoxic 2= present to TH cells)

Question 32

are NK cells in the dermis

Answer 32

yes

Question 33

what causes psoriasis

Answer 33

environmental factors (bacterial pharyngitis, mild trauma of skin, HIV, stress, B blockers, ingestion of lithium) in genetically susceptible individuals

Question 34

who is most likely to get atopic eczema

Answer 34

children

Question 35

what is the cause of atopic eczema

Answer 35

genetic and environmental factors= impairment of barrier function - mutatino in fillagrin gene - decreased AMP in skin immune cells actracted to stressed KC, like in psoriasis defective barrier allows access/sensitisation to allergen- promotes colonisation

Question 36

name 3 autoimmune skin conditions

Answer 36

psoriasis, vitiligo, systemic lupus erythematosus

Question 37

what causes skin problems with lupus

Answer 37

faulty apoptosis causes DNA and antigens to accumulate resulting in antibodies against own DNA

Question 38

what are causes of secondary immunodeficiency

Answer 38

AIDs, malignancy, aging, diabetes, renal malfunction, burns, alcoholic cirrhosis, malnutrition, obesity

Question 39

what mediates type 1 hypersensitivity

Answer 39

IgE

Question 40

describe the process of allergies

Answer 40

early exposure to allergen causes production of IgE which binds to FCER1 on mast cells. later exposure causes rapid crosslinking of receptors, signal transduction and degranulation of the mast cells

Question 41

what mediates type 2 and 3 hypersensitivity

Answer 41

IgG and IgM

Question 42

what mediates type 4 hypersensitivity

Answer 42

TH1 cells

Question 43

what hypersensitivity reaction is important in autoimmunity and transplantation

Answer 43

type 2

Question 44

what is an arthus reaction

Answer 44

type 3 hypersensitivity reaction (slower than type 1 but faster than type 4)

Question 45

which hypersensitivity reaction is delayed, give examples

Answer 45

type 4; contact allergy