Immuno 1: Immune Response To Infection/primary Immune Deficiencies 1

Question 1

List 4 ways in which the skin is able to act as a barrier to infection ?

Answer 1

tightly packed keratinised cells
Low PH
Low oxygen tension
Sebaceous glands- hydrophobic oils, lysosymes, ammonia, defensins

Question 2

List 4 ways in which the mucous membrane acts as a barrier to infection ?

Answer 2

Secretory IgA in the mucous- prevents bacteria from attaching and penetrating

Lysosymes
Lactoferrin- starves bacteria of iron
Cilia- actively traps and removes bacteria

Question 3

Which receptors allow cells of the innate immune system to recognise pathogens ?

Answer 3

PRRs - pattern recognition receptors

Question 4

List 3 polymorphonuclear cells ?

Answer 4

Neutrophils
Eosinophils
Basophils

Question 5

How do Neutrophils detect immune complexes ?

Answer 5

They have Fc receptors for the Immunoglobulin (antibody) in the complex

Question 6

Give one example of how neutrophils and Macrophages differ in function ?

Answer 6

Macrophages can also phagocytose pathogens but they are able to process the antigen and present the antigen to T cells

Question 7

Give 2 examples of PPRs ?

Answer 7

Toll like receptors

Mannose receptors

Question 8

Give 3 examples of opsonins ?

Answer 8

Antibodies
Complement
Acute phase proteins - CRP

Question 9

Give 2 examples of enzymes involved in oxidative killing of pathogens ?

Answer 9

NADPH oxidase - converts oxygen into reactive oxygen species

Myeloperoxidase- catalysts the production of HCL acid

Question 10

Give 2 examples of enzymes involved in non-oxidative killing of pathogens ?

Answer 10

Lactoferrin

Lysozyme

Question 11

What is pus ?

Answer 11

Collection of dead and dying neutrophils in infected tissues

Question 12

Which inhibitory receptors stop NK cells from destroying self cells ?

Answer 12

HLA receptors

Question 13

Which activating receptor causes NK cells to become cytotoxic ?

Answer 13

Heparan sulphate receptors

Question 14

Which chemokine receptor mediates the migration of dendritic cells into the lymphatics to lymph nodes ?

Answer 14

CCR7

Question 15

What is the role of Dendritic cells ?

Answer 15

They reside in peripheral tissue and can phagocytose pathogens.
They then migrate into the lymphatics and present the processed antigen to T cells to prime the Adaptive immune system.

Question 16

Where does lymph re enter the circulation ?

Answer 16

Thoracic duct

Question 17

How do NK cells recognise infected cells ?

Answer 17

The infected cell (e.g dendritic cell )will down-regulate inhibitory molecules such as HLA and up-regulate activatory molecules such as modified pathogen antigen.

The NK cell can now recognise the cell as altered cell and starts cytotoxic killing

Question 18

List 2 organs that are considered primary lymphoid organs ?

Answer 18

Bone marrow

Thymus

Question 19

Where does T cell maturation occur ?

Answer 19

Thymus

Question 20

Where do B cells undergo affinity maturation and isotope switching ?

Answer 20

Germinal centres

Question 21

Give 3 examples of secondary lymphoid organs ?

Answer 21

Lymph nodes
Spleen
MALT- mucosal associated lymphoid tissue

Question 22

What does the TCR do ?

Answer 22

Recognises peptide presented by the target or antigen presenting cell (APC)

Question 23

Which T cells recognise peptide presented by HLA Class 1 ?

Answer 23

CD8+ T cells

Question 24

Which T cells recognise peptide presented by HLA Class 2 ?

Answer 24

CD4+ T cells

Question 25

Which T cells are thought to be associated with Autoimmune disease ?

Answer 25

Th17 T cells

Question 26

Give 2 ways in which CD8+ T cells cause cytotoxic killing of cells infected by intracellular pathogens e.g viruses

Answer 26

Perforin (forms a pore into cell ) and granzyme

Express Fas Ligands

Question 27

Which T cells express Foxp3 and CD25 ?

Answer 27

T reg cells

Question 28

Which T cell helps in B cell maturation ?

Answer 28

Tfh cells (follicular helper)

Question 29

What is somatic hypermutation ?

Answer 29

The variable region of the B cell antibodies / receptor are edited

Question 30

What are the 3 pathways of complement activation ?

Answer 30

Classical
Alternative
MBL- mannose binding leptin

Question 31

How is the classical complement pathway activated ?

Answer 31

Immune complexes

Question 32

How is the MBL complement pathway activated ?

Answer 32

MBL binds to a microbial carbohydrate such as mannose

Question 33

How is the alternative complement pathway activated ?

Answer 33

Bacterial cell walls components bind directly to C3z

Question 34

What triggers the formation of the MAC (membrane attack complex) ?

Answer 34

activation of C3 convertase (common pathway of all 3 complement pathways)