CMB1003/L19 Innate Defences against Infection

Question 1

Give 3 elements of the innate immune response.

Answer 1

Barriers
Cellular defences
Molecular defence (humoral factors)

Question 2

Give 3 examples of physical and chemical barriers to infection.

Answer 2

Skin
Mucus membranes
Lysozymes in tears
Acid in stomach

Question 3

Give 3 examples of antibacterial enzymes.

Answer 3

Lysozyme
Secretory phospholipase A2
Tears, saliva, phagocytes

Question 4

What is the role of PRRs (pattern recognition receptors)?

Answer 4

Allow identification of pathogens

Question 5

Describe toll-like receptors. (2)

Answer 5

10 in humans
Each has own repertoire of pathogen-associated molecular patterns (PAMPs)

Question 6

What is a NOD-like receptor? (2)

Answer 6

Intracellular
Nucleotide-binding oligomerisation domain

Question 7

Give the 3 types of PRR.

Answer 7

Toll-like receptors
NOD-like receptors
RIG-I-like helicases

Question 8

What kind of molecules can PAMPs be? (4)

Answer 8

Mannose-ruch oligosaccharides
Peptidoglycans
Lipopolysaccharides
Unmethylated CpG DNA

Question 9

What are leucocytes produced from?

Answer 9

Pluripotent haematopoietic stem cells in bone marrow

Question 10

Give 3 types of granulocytes.

Answer 10

Neutrophils
Eosinophils
Basophils

Question 11

Give 3 types of leucocytes.

Answer 11

Lymphocytes
Monocytes
Granulocytes
Tissue mast cells

Question 12

Give 2 types of cellular defence and their goal.

Answer 12

Phagocytosis
Extracellular killing
Goal - inflammation

Question 13

What can occur if there is a defect in phagocytes? (3)

Answer 13

Bacterial infections
Fungal infections
Recurrent infections

Question 14

Describe neutrophils. (3)

Answer 14

Short-lived (<24hr)
Multi-lobed nucleus
Abundant in sites of acute inflammation

Question 15

Describe mononuclear phagocytes. (3)

Answer 15

Monocytes in blood
Macrophage in tissue
Longer lived cells (months)
Monocyte->macrophage

Question 16

Give the 5 stages of phagocytosis.

Answer 16

Recognition
Internalisation
Fusion
Killing
Digested products released

Question 17

Describe oxygen-dependent killing. (2)

Answer 17

Reactive oxygen intermediates bacteriostatic or bactericidal
H2O2 + myeloperoxidase + halid -> halogenation and killing

Question 18

Give 3 additional functions of macrophages.

Answer 18

Can be activated by bacterial products or cytokines
Secrete soluble factors (cytokines)
Present antigen to lymphocytes

Question 19

What is extracellular killing effective against? (2)

Answer 19

Organisms too large for phagocytosis
Infected cells

Question 20

Give 2 cells involved in extracellular killing.

Answer 20

Eosinophils
Natural killer cells

Question 21

What is the function of eosinophils?

Answer 21

Killing of antibody-coated parasites

Question 22

What is the function of natural killer cells? (2)

Answer 22

Active against viral infected cells
Attack some tumour cells

Question 23

What are NK cells activated by? (3)

Answer 23

IFNa
IFNb (type 1)
IL12

Question 24

What is the function of NK cells? (2)

Answer 24

Produce IFNy
Contain viral infections whilst adaptive/specific response kicks in

Question 25

What is the function of cytokines?

Answer 25

Stimulate or inhibit activity, proliferation or differentiations of other cells

Question 26

Give 3 groups of cytokines.

Answer 26

Interferons
Lymphokines
Interleukins
Chemokines

Question 27

How might a helminth be killed?

Answer 27

Eosinophils secrete chemicals to destroy them