10.17.2022. Study Questions

Question 1

Describe the role of dendritic cells in T cell activation.

Answer 1

collect antigens, travel to regions where naive T cells gather, and simultaneously
1. present various pieces of the antigen
2. produce surface proteins called co-stimulatory molecules if the antigen being presented is microbial or otherwise represents “danger,” ie SIRENS!

Question 2

Which cells express MHC class I, to which T cell type do they present antigen, and which antigen do they present?

Answer 2

• All body cells except RBCs (aka all nucleated cells) are the waiters that present endogenous antigen food on an MHC I plate to cytotoxic T cells
• Dendritic cells are waiters that present either type of food on either plate

Question 3

Which cells express MHC class II, to which T cell type do they present antigen, and which antigen do they present?

Answer 3

• Macrophages/B cells are the waiter that serve exogenous antigen food on an MHC II plate to helper T cells
• Dendritic cells are waiters that present either type of food on either plate

Question 4

How does a Tc cell determine if a “self” cell is infected/corrupt?

Answer 4

by inspecting portions from inside the cell (endogenous proteins) that are presented on MHC I molecules

Question 5

Compare and contrast the outcome of antigen recognition by a Tc cell versus a Th cell

Answer 5

Tc: reads endogenous antigens on MHC I and says “this cell is likely infected and should be destroyed via apoptosis
Th: reads exogenous antigens on MHC II and says “there is likely an infection, and immune response should be activated via B cells, T cells, and macrophages

Question 6

What is the outcome of B cell activation?

Answer 6

plasma cells –> secrete antibodies
memory B cells to fight infection faster next time

Question 7

What is the outcome of T cell activation?

Answer 7

Tc : induce apoptosis in affected cell
Th: activate immune response

Question 8

How do NK cells protect against certain viruses? (2)

Answer 8

• mediate antibody-dependent cellular cytotoxicity
• induce apoptosis in host cells that are not bearing MHC I molecules on their surface

Question 9

Compare and contrast T-dependent antigens and T-independent antigens

Answer 9

Dependent: B cells that recognize them require help from Th cells, aka you can only get the immune response with the help of Th cells
Independent: antigens that can activate B cells without the assistance of a Th cell