Immunology 3

Question 1

IRAK-4 deficiency - what infections prone to?

Answer 1

Pyogenic infections

Question 2

Major receptors to capture fungal?

Answer 2

Dectin 1/2 - then stimulate Th17 differentiation

Question 3

NOD-like receptors function?

Answer 3

Assemble inflammasome and signal Nf/MAPK pathway

Inflammasome senses DAMP/PAMP and activate caspase 1 = releases IL1

Question 4

Familial Mediterranean fever mutation and pathogenesis?

Clinical features?

Answer 4

Mutation of Pyrin gene - pyrin is inflammasome = triggers pyroptosis

Clinical features
-Fever/Serositis/Arthritis

Question 5

Hyper Ig-D syndrome pathogenesis?

Answer 5

Defective RHoA = Pyrin very active and inflammasome = pyroptosis

Eg. of HAMP = Homeostasis altering molecular process

Question 6

How NOD2 contributes to Crohn’s disease?

Answer 6

NOD2 in Paneth cells of terminla ileum = produces AMP - antimicrobial peptide duhhh ( products against bacteria) and cause Autophagy of bacteria

Crohns has dysfunctional NOD2

Question 7

IL1 function in innate immune?

Answer 7

Increases expression of adhesion molecules - transmigration leucocytes to infection site = fever!

Question 8

Most potent source of Interferon?

Answer 8

Plasma Dendritic Cells

Question 8

Most potent source of Interferon?

Answer 8

Plasmacytoid Dendritic Cells

Question 9

Summary of Innate immune system components and function?

Answer 9

CLR = Glue ( stick to pathogens)
NLR = Inflammasomes - caspase 1 releases IL1
TLR = cell activators (Gram -ve, stimulate B cells)
RLR = RNA sensors in cytoplasm - release IL1
AIM2/cGAS = DNA sensors in cytoplasm

Question 10

Chronic granulomatous disease

• Nitroblue tetrazolium check what?
• Flow cytometry check what?

Answer 10

• Nitroblue checks activated neutrophils

- Flow cytometry checks dihydrorhodamine ( burst neutrophils)

Question 11

What are chemokines?

Answer 11

directs movement of leucocytes eg. CCR5/CXCR4

Question 12

What activates NK cell to kill?

Answer 12

ADCC - antibody dependent ( Ig G and Ig E)
Activating receptors - bind to viral proteins
Devoid of MHC I ( cancer/virus) - so NK will attack yum yum
Cytokines - chemokines

Question 13

Ig G does what?
Ig M does what?
Ig A does what?

Answer 13

Ig G - complement, Opsonisation/neutralisation
Ig M - complement, Agglutination ( low affinity, high avidity)
Ig A - inhibit colonisation and binds to mucus to trap pathogens

Question 14

what site of Antigen binding on Ig most variable?

Memory B cells express what CD?

Answer 14

CDR3

Memory B cells = CD27

Question 15

what is Hapten?

Answer 15

Small molecule ( no immune response) but when linked to large molecule ( carrier ) = elicits immune response

Question 16

Common variable immunodeficiency (CVID) a/w what Ig?

Answer 16

Ig A deficiency

Question 17

Ig G subclass deficiency - treatment?

Ig A subclass deficiency - important to take note regarding infusion?

Answer 17

Ig G - tx is IVIG

Ig A - mucosal defect, if give infusion needs Ig A deficient donor or triple wash product

Question 18

2 types of Antibody forming cells from B cells ie;
Plasmablasts
Plasma cells
-function and characteristics?

Answer 18

Plasmablasts = Rapid activation, short lived, Ig M secretion

Plasma cells = activated from germinal centre, long lived, reside in bone marrow, secretes all antibodies!

Question 19

B-cell lymphoma means?

Answer 19

clone of identical B cells having = Identical VDJ rearrangement ( heavy chain)

Question 20

Heavy chain ( VDJ rearrangement) mediated by? and B cell becomes?

Light chain ( VJ rearrangement) mediated by? and B cells becomes?

Answer 20

Heavy Chain - RAG genes = Pre-B cell

Light chain - Rag-mediated = Immature naive B cell ( express surface Ig M)

Question 21

B Agamaglobulinemias vs X-linked agammaglobulinemia?

Answer 21

B-agamma = Btk deficiency = No B cells, No Ig

X-linked agamma = Btk MUTATION = No B cells, No IgG, EPG = hypogamma

Question 21

B Agamaglobulinemias vs X-linked agammaglobulinemia?

Answer 21

B-agamma = Btk deficiency = No B cells, No Ig

X-linked agamma = Btk MUTATION = No B cells, No IgG, EPG = hypogamma

Question 22

Mature B cells have what expression Ig?

Answer 22

Mature B cell = Ig M and Ig D

Question 23

Mature B cell needs T cell co-stimulation to do what?

Answer 23

Activation and proliferation
Differentiate into memory B cells and Antibody forming cells
Undergo somatic hypermutation to gain isotype switching and affinity maturation

Question 24

What happens in Hyper Ig M syndrome?
clinical features?
Tx?

Answer 24

Absence of CD40 and CD40L stimulation - so no somatic hypermutation/no isotype switching/ no Immunoglobulin/ no memory B cells

• Neutropenia and recurrent bacterial infections ( PJP!)
• Low Ig A,G,E
• Ig M Very HIGH, Ig D normal

Tx- IVIG and bactrim prophylaxis

Question 25

Ig M is what affinity, avidity?

Ig G is what affinity, avidity?

Answer 25

Ig M is low affinity ,HIGH avidity

Ig G is HIGH affinity, HIGH avidity

Question 26

EBV enters and infect B cell via CD what?

Answer 26

CD21 - 3D receptor

Question 27

How B cell activated without T cells?

Answer 27

TLR

Multiple repetitive polysaccharides

Question 28

Which T cells facilitate allograft rejection?

Answer 28

CD4 - T helper cells

Question 29

T cells undergo what type of somatic changes?

Answer 29

Somatic rearrangement

Question 30

How T cell activated without APC/MHC presentation?

Answer 30

Super-antigens bind to MHC: peptide groove

• Toxic shock syndrome
• Staphylococcus enterotoxins