Hubs191 Immune System

Front 1

What are leukocytes?

Back 1

- White blood cells
- Minor constituent of blood
- Main cells involved in immunity

Front 2

What is an antigen?

Back 2

- Anything that has the potential to be recognized by the immune system.

Front 3

What is a foreign antigen?

Back 3

- Anything from the outside
- This includes transplants, pathogens and some chemicals

Front 4

What is an auto-antigen?

Back 4

- Anything that is from self
- Immune system normally tolerant of auto (self) antigens
- However, in autoimmune disorders these may be recognised.

Front 5

What is the purpose of antigen uptake?

Back 5

- Clearance of pathogens (innate response)
- For presentation to T-cells (adaptive response)

Front 6

What happened 500 million years ago that was the beginning of the adaptive immune response?

Back 6

- Phagocytes evolved to keep remnants of pathogens and display these to other cells of the immune system.

Front 7

Where did the adaptive immune response evolve from?

Back 7

- Jawed fishes

Front 8

What does MHC-I present?

Back 8

- Endogenous (intra-cellular) antigens
- Expressed on all nucleated cells

Front 9

What does MHC-II present?

Back 9

- Exogenous (extra-cellular) antigen
- Expressed only on antigen presenting cells

Front 10

What is displayed on MHC?

Back 10

- Peptides generated from protein antigens

Front 11

What happens after the MHC/peptide complex is formed?

Back 11

- It can then be surveyed by antigen-specific t-cells

Front 12

Describe MHC-I processing

Back 12

- Intracellular (virus)
- Antigenic proteins are degraded to peptides in cytoplasm
- Peptides are imported into the endoplasmic reticulum.
- Peptide loading of MHC-I takes place in the ER (in order for immune surveillance).
- MHC-I = all nucleated cells (therefore most cells except red blood cells).

Front 13

Describe MHC-II antigen processing

Back 13

- Phagocytosis of exogenous antigen
- Forms vesicle - phagolysosome
- Antigenic proteins are degraded in acidic phagolysosome (therefore not directly in the cytoplasm)
- Peptide loading of MHC-II takes place in phagolysosome.

Front 14

What are peptides?

Back 14

- Fragments of protein antigen that are displayed by MHC-I and MHC-II