Lecture 6: Adaptive Immunity 3- Part 1

Question 1

Why do T cells need antigen presentation?

Answer 1

T cells do not recognise native antigen

Question 2

Name the three antigen presenting cells?

Answer 2

1) Dendritic cells
2) Macrohphages
3) B cells

Question 3

Which co-stimulatory molecules does the activated dendritic cells?

Answer 3

CD80 and CD86

Question 4

How does the macrophages and B cells present antigens?

Answer 4

1. Macrophages-engulf pathogens and process them into immunogenic peptides
2. B Cells internalize the antigen which binds to its BCR and present it incorporated to MHC II molecules

Question 5

How are the antigens delivered to the surface?

Answer 5

MHC

Question 6

Which cells does MHC I and MHC II found on?

Answer 6

-MHC I- all nucleated cells- intracellular antigens such as viruses.
MHC II- found APC and typically extracellular antigens such as bacteria

Question 7

What is antigen processing and what does it require?

Answer 7

• Enzymatic process of DEGRADING proteins through PROTEASES into antigenic peptides
• Requires ATP and movement of endocytic vesicles

Question 8

what are the intracellular peptides presented by and how?

Answer 8

Intracellular antigens are presented by MHC I: via PROTEASE and the PROTEASOMES in the cytosol then TRANSPORTED into ER to be further processed.

Question 9

Antigens presented by MHC I are recognised by?

Answer 9

CD8 and cytotoxic T cells

Question 10

what are the extracellular peptides presented by and how?

Answer 10

• MHC II
• ENDOCYTOSIS of the antigen
• ENCASED in endosomes that acidify and activate protease to degrade the antigen
• antigen TRANSPORTED into endocytic vesicles where they bind peptide antigen then travel to the cell surface

Question 11

Antigens presented by MHC II are recognised by?

Answer 11

CD4 Helper T cells