Lec 45: Adaptive Immunity II (NSD) Flashcards

1
Q

What are the two subsets of helper T cells?

A

Th1 and Th2

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2
Q

What type of cells to Th1 cells attach to?

A

Dendritic cells and Macrophages

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3
Q

What receptors do Th1 cells directly bind to?

A

MHC II-antigen complexes; CD40

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4
Q

What are the primary cytokines secreted by TH1 cells?

A

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

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5
Q

What does interferon gamma do?

A
  1. Activates “resting” macrophages

2. Inhibits Th2 activity

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6
Q

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

A

Interleukin-12 (IL-12)

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7
Q

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

A
  1. CD8+ and NK cells: More IFN-gamma secretion and increased cytolytic activity
  2. Naive CD4 cells –> Th1 cells –> increased IFN-gamma secretion
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8
Q

What type of cells to Th2 cells attach to?

A

B cell presenting specific antigen

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9
Q

What receptors do Th2 cells directly bind to?

A

MHC II-antigen complexes; CD40

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10
Q

What are the primary cytokines secreted by TH2 cells?

A

IL-4; IL-5

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11
Q

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

A
  1. B-cell differentiation and antibody production

2. Inhibition of Th1 cells

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12
Q

What is the primary function of CD8 cells?

A

Induce apoptosis in cells infected with viruses/intracellular pathogens

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13
Q

What happens to a virus once inside a dendritic cell?

A
  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
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14
Q

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

A
  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

  1. Nearby CD4 T cell helps CTL binding by inducing B7 expression on surface of APC
  2. Nearby CD4 T cell helps CTL binding by releasing IL-2
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15
Q

What types of cells can naive CD8 cells differentiate into?

A

Effector T cells or memory T cells

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16
Q

How do naive T cells differentiate and reach infected sites?

A
  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
Q

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

A
  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)