Immunodeficiency

Question 1

Primary immunodeficiency

Answer 1

Inherent defect within the immune system, usually genetic and rare

Question 2

Secondary immmunodeficiency

Answer 2

Immune system is affected due to external causes

Question 3

Secondary causes of immmunodeficiency

Answer 3

• Breakdown of physical barriers - cystic fibrosis
• Protein loss
• Malignancy
• Drugs
• Infection

Question 4

Pathogen recognition receptors

Answer 4

Recognise conserved pathogen associated patterns (PAMPS)

- Phagocytes used receptors to detect pathogens

Question 5

Examples of pathogen recognition receptors

Answer 5

TLR4 - lipopolysaccharide

TlR5 - Flagellin

Question 6

IRAK4 deficiency features

Answer 6

• Cant recruit more immune cells very well
• Can recognise bug but can’t produce response
• Recurrent bacterial infection - pneumonia

Question 7

IRAK4 treatment

Answer 7

• Prophylactic antibiotics

- IV immunoglobin if severe

Question 8

What occurs in the phagolysosome to kill the pathogen

Answer 8

• Oxygen is reduced to superoxide which forms hypochlorous acid
• Acid kills pathogen

Question 9

Chronic Granulomatous disease features

Answer 9

• Macrophages cannot destroy pathogen as acid is not produced
• Stops NADPH complex
• Women typically carriers, men affected - X linked
• Chronic abscesses

Question 10

What is granuloma

Answer 10

A collection of macrophages

Question 11

Treatment of Chronic Granulomatous disease

Answer 11

Hemopoietic stem cell transplant

Question 12

Test for Chronic Granulomatous disease

Answer 12

• Neutrophil function test
• Nitro blue tetrazolium dye - electron released by NADPH is not reducing oxygen so it ca be detected.
• Healthy neutrophils turn clear to purple - unhealthy remain clear

Question 13

What is Complement

Answer 13

• Non immunoglobin proteins that contribute to:
• Cell lysis
• Control of inflammation
• Stimulate phagocytosis

Question 14

Complement function

Answer 14

Complement should lyse foreign cells

- patients serum should lyse sheep erythrocytes

Question 15

Complement deficiency

Answer 15

• C2,C4 deficiency = SLE, infections, myositis
• C5-C9 deficiency = form membrane attack complex
• Recurrent bacterial meningitis

Question 16

Treatment of Complement deficiency

Answer 16

Prophylactic penicillin B + vaccinated against meningitis

Question 17

X-Linked agammaglobulinaemia

Answer 17

• Defect in Burtons Tyrosine Kinase
• BTK needed for B cell signalling and maturation
• B cell maturation not completed in bone marrow
• normal T cells, No B cells

Question 18

IgA deficiency

Answer 18

• IgA not produced- more prone to autoimmune disease

-

Question 19

X linked hyper IgM syndrome

Answer 19

patients cannot switch from IgM to IgG during immune response so get left with high levels of IgM

Question 20

Defects in B cells

Answer 20

• Loss of antibody secretion

- Leads to recurrent bacterial infection with pus-forming organisms

Question 21

Secondary antibody deficiency due to drugs

Answer 21

• Rituximab kills B cells
• Methotrexate hits fast growing cells - can attack neutrophils
• Azathioprine works on B/T cells
• Prednisolone works on whole organism

Question 22

How does HIV create immunodeficiency

Answer 22

HIV kills CD4 cells

Question 23

Chicken pox clinical features

Answer 23

Mild disease forms typical vesicles

• Severe = fulminant disease
• Haemorrhagic lesions + can get into lungs

Question 24

Severe combined Immunodeficiency (SCID)

Answer 24

• No T cells

- B cells don’t function without T cells

Question 25

SCID treatment

Answer 25

• Treated with antibiotics, antifungals, antivirals

- Only cure is a stem cell transplant

Question 26

SCID causes

Answer 26

• Defect/absence of critical T receptors - TCR common gamma chain
• Loss of communication - MHCII deficiency in B cells means cannot get T cell help
• Adenosine deaminase deficiency - no enzyme so metabolite accumulate and it toxic to lymphocytes