Lec 45: Adaptive Immunity II (NSD) Flashcards Preview

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Flashcards in Lec 45: Adaptive Immunity II (NSD) Deck (17):
1

What are the two subsets of helper T cells?

Th1 and Th2

2

What type of cells to Th1 cells attach to?

Dendritic cells and Macrophages

3

What receptors do Th1 cells directly bind to?

MHC II-antigen complexes; CD40

4

What are the primary cytokines secreted by TH1 cells?

Interferon-gamma (IFN-gamma); Interleukin-2 (IL-2)

5

What does interferon gamma do?

1. Activates "resting" macrophages
2. Inhibits Th2 activity

6

What major cytokine is produced by APCs when they come in contact with intracellular pathogens?

Interleukin-12 (IL-12)

7

What effect does IL-12 have on T cells and natural killer (NK) cells?

1. CD8+ and NK cells: More IFN-gamma secretion and increased cytolytic activity
2. Naive CD4 cells --> Th1 cells --> increased IFN-gamma secretion

8

What type of cells to Th2 cells attach to?

B cell presenting specific antigen

9

What receptors do Th2 cells directly bind to?

MHC II-antigen complexes; CD40

10

What are the primary cytokines secreted by TH2 cells?

IL-4; IL-5

11

What effect do IL-4 and IL-5 have on their target cells and on Th1 cells?

1. B-cell differentiation and antibody production
2. Inhibition of Th1 cells

12

What is the primary function of CD8 cells?

Induce apoptosis in cells infected with viruses/intracellular pathogens

13

What happens to a virus once inside a dendritic cell?

1. Viral proteins are produced in the cytosol on the cell
2. Viral proteins are degraded
3. Degraded proteins are transported from cytosol to ER
4. Peptide-MHC class 1 complexes formed in ER
5. Complexes move to cell surface
6. Complexes are recognized by CD8 cytolytic lymphocytes

14

What are the differences in the 3 major pathways for activation in naive CD8 (CTL) cells?

1. Without help from CD4 cells
1a. CTL binds to MHC I-antigen complex and B7 on virus-infected cell
1b. IL-2 is produced by CTL and drives its own proliferation and differentiation

2+3 With help from CD4 cells

2. Nearby CD4 T cell helps CTL binding by inducing B7 expression on surface of APC

3. Nearby CD4 T cell helps CTL binding by releasing IL-2

15

What types of cells can naive CD8 cells differentiate into?

Effector T cells or memory T cells

16

How do naive T cells differentiate and reach infected sites?

1. Naive T cells meet dendritic APCs n the lymph node
2. Naive T cells develop into effector cells in the lymph node
3. Effector T cells exit into efferent lymph and travel to infected cells

17

How do CD8+ cells (CTLs) kill the cells they target?

1. Recognize MHC I complex on infected cells
2. CTL releases cytolytic granules on surface of the infected cell
3. Infected cell begins to lyse; apoptosis occurs
4. Recognize MHC 1 complex and Fas on neighboring infected cell and process repeats (if applicable)

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