Intro to immunology

Question 1

What are the major physical barriers to infection? [5]

Answer 1

Saliva
Mucocilliary Escalator
Gastric Acid
Natural Flora
Flushing & urine pH

Question 2

What cell types are involved in innate immunity?
In blood [4]
In tissue [3]

Answer 2

In blood:

• NK cells
• Basophils
• Eosinophils
• Monocytes

In Tissue

• Mast Cells
• Macrophages
• Dendritic Cells

Question 3

By what mechanisms does the innate immune system function? [6]

Answer 3

1) Inflammation
2) Recruiting immune cells
3) Complement Activation
4) Opsonisation
5) Phagocytosis
6) NK cytotoxicity

Question 4

What are cytokines?

Answer 4

Molecules that regulate the nature, duration & intensity of immune responses by binding to specific receptors
E.g. Interleukins, TNF-alpha, chemokines & TGF-beta

Question 5

Where are cytokines made? [2]

Answer 5

Th cells & Macrophages

Question 6

Which cytokines are pro and anti-inflammatory?

Answer 6

Pro-inflammatory = TNF-alpha, IL-1, IL-6 & chemokines

Anti-inflammatory = IL-10 & TGF-beta

Question 7

Describe what happens during inflammation? [6]

Answer 7

Pattern Recognition Receptors (PRR) detect a breach in defence/foreign body and trigger:

• Vasodilation
• Vascular permeability
• Cell Adhesion Molecules
• Chemotaxis
• Sensitivity to Pain

Question 8

How is complement activated? [2]

Answer 8

C3 is activated first. By any of the 3 pathways, Classical/Lectin/Alternative

Question 9

What are the functions of complement? [4]

Answer 9

Chemotaxis of phagocytes
Opsonisation
Lysis of micro-organisms
Maintain solubility of Ab/Ag complexes

Question 10

What is Opsonisation? [2]

Answer 10

Tagging cells for phagocytosis

Done by complement C3b/C4b, antibodies & plasma cells

Question 11

What do NK cells do in innate immunity? This mechanism is also used in another cell in adaptive immunity.

Answer 11

Perforin-induced Apoptosis

Question 12

Define an antigen vs antibody?

Answer 12

Antigen is any molecule that induces an immune response. An antibody is a glycoprotein made by b cells that binds antigens

Question 13

How do adaptive immune cells recognise antigens?

Answer 13

B cells/Abs detect BCR directly

T cells detect MHC on antigen presenting cells

Question 14

Immune Tolerance is a process of ensuring our Lymphocytes are tolerant towards our own tissues. Where does this occur?

Answer 14

Central Tolerance:
T = Thymus
B = Marrow

Peripheral Tolerance:
- 2nd lymphoid organs & circ

Question 15

What happens during central tolerance? [3]

Answer 15

B cells assessed for self-reacting BCR in the marrow.

T cells undergo +ve (can they recognise foreign antigen?) & -ve (Do they not recognise self-antigens) tolerance testing in the thymus.

Any failures die

Question 16

How does peripheral tolerance work?

Answer 16

Regulatory T cells destroy self-reactive lymphocytes

Question 17

What are the major types of T cells? [3]

Answer 17

Cytotoxic (CD8+)
Helper (CD4+)
Regulatory

Question 18

Which type of Th cell attacks which type of pathogen?

Answer 18

Th1 targets intracellular pathogens

Th2 & Th17 target extracellular pathogens

Question 19

Other than peripheral tolerance, what else do regulatory T cells do? [2]

Answer 19

Secrete anti-inflammatory Cytokines (IL-10 & TGF-beta)

Suppress Th & cytotoxic T cells

Question 20

What are the major causes of Secondary Immune Deficiency?

Answer 20

Environmental e.g. malnutrition or trauma

Disease e.g. HIV, DM, malignancy or renal failure

Drugs e.g. Glucocorticoids, cyclosporin or Rituximab