Antibacterial response

Question 1

What are defensins?

Answer 1

• Anti-microbial peptides capable of killing by penetrating microbial membranes thus disrupting their integrity.
• They are active against bacteria, fungi and many enveloped and non-enveloped viruses.

Question 2

What are the two types of defensins?

What are the functions of them?

Answer 2

• There are two types: 𝛂-defensins and β-defensins.
• 𝛂-defensins are secreted mainly by neutrophils and by Paneth cells
• β-defensins are secreted by a broad range of epithelial cells, in particular, those in the respiratory tract, the skin and the urogenital tract.

Question 3

What can the complement system recognise?

Answer 3

LPS and peptolygylcan to activate the alternate complement pathway

Mannose can be detected to activate the lectin pathway

Question 4

What are the 3 pathways of the complement system?

Answer 4

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Question 5

What are the 3 functions of the complement system?

Answer 5

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Question 6

What are the role of complement receptors in phagocytosis

Answer 6

Bacteria can bind to complement receptors on phagocytes and then be engulfed leading to phagocytosis.

They can also bind to signalling receptors on macrophages to induce the synthesis of inflammatory cytokines

Question 7

How does the interaction between PRRs and PAMPS lead to inflammation?

Answer 7

1. PAMP binding by PRRs activates phagocyte
2. Phagocyte ingests microbes, englarges and increases metabolic activity
3. Activated phagocytes elevate antimicrobial activity

Question 8

What initiates inflammation in tissues?

Answer 8

Tissue damage

Question 9

Briefly describe the humoral and cellular immune response

Answer 9

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Question 10

Describe how The MHC class II pathway presents bacterial antigens derived from extracellular infections to helper CD4 T cells

Answer 10

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