IHO: Week 3

Question 1

What cytokines induce formation of Th1 cells? What lymphokines do Th1 cells secrete?

Answer 1

Induce formation: IL-12, IFNg

Lymphokines: IFNg –> activate classical macrophages (M1)

Question 2

What cytokines induce formation of Th17 cells? What lymphokines do Th17 cells secrete?

Answer 2

Induce formation: IL-6, TGF-B, IL-23

Lymphokines: IL-17, IL-22

Question 3

What cytokines induce formation of Th2 cells? What lymphokines do Th2 cells secrete?

Answer 3

Induce formation: IL-4

Lymphokines: IL-13, IL-4 –> activate alternative macrophages (M2)

Question 4

What lymphokines do Treg cells secrete to inhibit Th1, Th2, and Th17 cells?

Answer 4

IL-10 and TGF-B

Question 5

How does a CTL signal to an infected cell to undergo apoptosis?

Answer 5

First, the CTL binds to the infected cell’s Fas death receptor (CD95) with the CTL’s CD95L. Then the CTL also secretes granzymes and perforins to break open the infected cell’s membrane and degrade the infected cell’s contents.

CTLs are activated by IL-2 secretion from activated T helper cells and are converted into memory CTLs by IL-12.

Question 6

What are the other co-receptors found at TCR - MHC/peptide binding junction?

Answer 6

• CD2 binds to LFA-3 (co-stimulatory molecule)
• LFA-1 (leukocyte functional antigen (integrin)) binds to ICAM-1 (intercellular adhesion molecule).
• CD28 binds to B7 (aka CD80/CD86)
• CD45R binds to CD22

co-receptors add to binding affinity

Question 7

Antigen presented on MHC class I molecules was…?

Answer 7

processed in the presenting cell (typically via proteases) and is commonly referred to as an endogenous antigen. These antigens include viral genomes.

Question 8

Antigen presented on MHC class II molecules was …?

Answer 8

endocytosed from the surrounding environment and is commonly referred to as an exogenous antigen. These antigens are endocytosed by DCs and presented to Th cells

Question 9

What is the best APC and why?

Answer 9

DCs because the constitutively express both MHC I and II as well as B7 (one of the co-receptor stimulatory molecules needed to enhance binding affinity)

Question 10

What are some important structural features of MHC class I molecules?

Answer 10

B2 microglobulin
Closed binding cleft
Recognizes CD8+ surface markers

Question 11

What are some important structural features of MHC class II molecules?

Answer 11

a subunit and B subunit
Open binding cleft
Recognizes CD4+ surface markers