Immunology

Question 1

What is the immune system for?

Answer 1

To identify and eliminate micro-organisms and other harmful substances

Question 2

When should you think about iimmune deficiency with a patient?

Answer 2

When a patient presents with SPUR infections: 
Serious
Persistent
Unusual
Recurrent

Question 3

How do you define a serious infection?

Answer 3

Unresponsive to oral antibiotics

Question 4

How do you define a persistent infection?

Answer 4

There is early structural damage

Chronic infections

Question 5

How do you define an unusual infection?

Answer 5

Unusual organisms and sites

Question 6

How do you define a recurrent infection?

Answer 6

Two major or one major and recurrent minor infections in one year

Question 7

Bar SPUR, what are other features that are suggestive of primary immune deficiency?

Answer 7

• Weight loss/failure to thrive
• Eczema
• Chronic diarrhoea
• Mouth ulceration
• Family history

Question 8

How do you classify immunodeficiencies?

Answer 8

Primary - rare

Secondary - common, often subtle, often involves more than one component of the immune system

Question 9

What are the two arms of the immune system?

Answer 9

Innate and Adaptive - detect and destroy pathogen in different ways

Question 10

What cells are involved in the innate immune system?

Answer 10

Macrophages, neutrophils, mast cells and NK cells

Question 11

Which proteins are involved in the innate immune system?

Answer 11

Complement, Acute phase proteins and cytokines

Question 12

What is different about the innate immune system?

Answer 12

Recognises structures that are unique to infectious organisms
Essentially identical responses in all individuals

Question 13

What are the functions off the innate immune system?

Answer 13

• Rapid clearance of micro-organisms
• Stimulates the acquired (adaptive) immune response
• Buys time whilst the acquired immune system is mobilised

Question 14

What are the cells of the acquired immune system?

Answer 14

B & T lymphocytes

Question 15

What are the proteins of the acquired immune system?

Answer 15

Antibodies

Question 16

What is unique about the acquired immune system?

Answer 16

• Repertoire isn’t genetically encoded
• Acquired as a response to exposure to an antigen
• Responsive to an unlimited number of molecules
• Very specific
• Memory

Question 17

Which cells are the phagocytes?

Answer 17

Neutrophils and macrophages

Question 18

What are the functions of phagocytes?

Answer 18

Initiation and amplification of inflamm response
Scavenging of cellular and infectious debris
Ingest and kill micro-organisms
Resolution and repair

Question 19

Phagoyctes are particularly important in defence against which pathogens?

Answer 19

Bacteria and fungi

Question 20

What are the clinical features of phagocyte deficiencies?

Answer 20

Recurrent infections - may affect common and unusual sites

Commonly fungal infections (oral candida)

Question 21

What is Kostmann syndrome?

Answer 21

Rare autosomal recessive disorder

Question 22

What is the clinical presentation of Kostmann syndrome?

Answer 22

Infections usually within 2 weeks after birth - recurrent bacterial infection, systemic or localised infection

Question 23

What are the non specific features of Kostmann syndrome?

Answer 23

fever, irritability, oral ulceration and failure to thrive

Question 24

What are the supportive treatments of Kostmann syndrome?

Answer 24

Prophylactic antibiotics and antifungals

Question 25

What is the definitive treatment of Kostmann syndrome?

Answer 25

Stem cell transplantation | Granulocyte colony stimulating factor - specific growth factor to assist maturation of neutrophils

Question 26

What is leukocyte adhesion deficiency?

Answer 26

Rare primary immunodeficiency that's caused by a genetic defect in leukocyte integrins (CD18)

Question 27

What is the classical clinical presentation of leukocyte adhesion deficiency?

Answer 27

Characterised by marked leukocytosis and localised bacterial infections that are difficult to detect

Question 28

What are the three main types of pathogen recognition receptors?

Answer 28

Toll like receptors Scavenger receptors Lectin receptors

Question 29

What are opsonins?

Answer 29

Molecule that act as binding enhancers for the process of phagocytosis (include complement C3b, IgG antibody and CRP)

Question 30

How do opsonins work?

Answer 30

Bind to receptors on phagocyte surface | Phagocytes express Fc receptors - allow binding of antibody that is also bound to antigen

Question 31

What is chronic granulomatous disease?

Answer 31

Failure of oxidative killing mechanisms - deficiency of the intracellular killing mechanism of phagocytes - inability to generate oxygen free radicals

Question 32

How are the granulomas formed in chronic granulomatous disease?

Answer 32

Inability to clear organisms - excessive inflammation - persistent accumulation of neutrophils, macrophages and lymphocytes

Question 33

What are the features of chronic granulomatous disease?

Answer 33

``` Recurrent deep bacterial infections (especially staphylococcus, aspergillus, pseudomonas cepacia) Recurrent fungal infections Failure to thrive Lymphadenopathy and hepatosplenomegaly Granuloma formation ```