L33

Question 1

What is antigen?

Answer 1

Anything (foreign or self) that has the potential to be recognised by the immune system

Question 2

How does an autoimmune disease occur and what is an example?

Answer 2

The immune system is usually tolerant of self-antigen, but when it recognises self-antigen and attacks it as if it is foreign. This is an autoimmune disorder.

A good example is Rheumatoid arthritis.

Question 3

What is the purpose of antigen uptake?

Answer 3

• Clearance of pathogens (innate response)

- For presentation to T cells (adaptive response)

Question 4

What type of immunity do invertebrates, vertebrates and jawless fish have?

Answer 4

Invertebrates - only innate immunity
Vertebrates - Both innate and adaptive immunity
Jawless fish - Both innate and adaptive (but their adaptive system is based on different structures compared to vertebrates)

Question 5

How do antigen presenting peptides of pathogens?

Answer 5

Bacteria/fungi are swallowed by an antigen presenting cell. The material ends up in a destructive vesicle inside the phagolysosome. Some fragments are recycled, these fragments are the peptides from proteins of the ingested bacteria/fungi. The peptides are loaded on MHC-II and sent to the cell surface to present them as a peptide-MHC complex.

Question 6

Where are the peptides found that each MHC binds to?

Are they exogenous or endogenous?

Answer 6

MHC-I presents endogenous antigen
It presents material found inside the cytoplasm

MHC-II presents exogenous antigen
It presents peptides coming from outside the cell

Question 7

What are the two arms of the adaptive immune system?

Answer 7

CD4 and CD8