BIOL 465 Midterm 2 Flashcards

1
Q

What are the 3 main types of T cells in the innate immune system?

A
  • Helper (TH)
  • Regulatory (Treg)
  • Cytotoxic (TC)
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2
Q

What are the 3 main components of the innate (cellular) immune system?

A
  • Antigen-presenting cells (dendritic cells, macrophages)
  • Cytotoxic cells (NK cells, macrophages)
  • Proteins (complement system)
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3
Q

How do Treg cells help to regulate the adaptive immune system?

A

By inhibiting TH and TC cells.

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4
Q

What 2 processes are stimulated by TH cells?

A
  • Proliferation of plasma cells (B cells and other humoral immune cells)
  • Killing of target cells by TC cells
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5
Q

What does HIF stand for (as in HIF1 & HIF2)?

A

Hypoxia-inducible factor.

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6
Q

What type of cell differentiates to become a tumour-associated macrophage (TAM)?

A

Monocytes.

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7
Q

What are the most abundant immune cells involved in tumour development?

A

Macrophages.

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8
Q

How do TAMs initially respond to the levels of hypoxia found in tumours?

A

By upregulating transcription factors, including HIF1 & HIF2, that in turn activate genes that promote tumour growth and proliferation.

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9
Q

What are the 4 main types of genes activated by transcription factors upregulated in macrophages in response to hypoxia in tumours?

A
  • Mitogenic genes
  • Proinvasive genes
  • Proangiogenic genes
  • Prometastatic genes
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10
Q

What are the 2 main molecules recognized by anti-tumour macrophages as part of normal innate immunity?

A
  • Lipopolysaccharide (LPS)
  • Interferon-γ (INF-γ)
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11
Q

What is the main function of anti-tumour macrophages (MACs) in the normal innate immune response?

A

To recognize LPS or INF-γ as a marker of foreign or abnormal material and to phagocytize an infectious pathogen or tumour cell once recognized.

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12
Q

What type of macrophage responds to LPS or INF-γ?

A

Anti-tumour macrophages (MACs).

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13
Q

What type of macrophage responds to hypoxia with an area of rapid tissue growth?

A

Tumour-associated macrophages (TAMs).

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14
Q

Why does hypoxia trigger an innate immune response by TAMs?

A

TAMs recognize the hypoxic tissue as a wound site and are attracted to it in order to fix the wound.

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15
Q

What is interleukin-10 (IL-10)?

A

A proangiogenic cytokine, released by TAMs in areas of hypoxia, that stimulates HIF1α and VEGF to promote angiogenesis.

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16
Q

What is the combined effect of TAM cytokines, such as IL-10, and glucocorticoids in a tumour microenvironment?

A

The cytokines are anti-inflammatory and the combination is immunosuppressive, resulting in lympocyte levels that are too low to resolve the invasion of tumour cells.

17
Q

What are the effects of IL-6 and TGF-α released by TAMs in a tumour microenvironment?

A

They promote growth, division, and proliferation of cancer cells.

18
Q

How do MACs attack unusual cells that may become cancerous?

A

By releasing TNF-α at low local levels, which induces apoptosis in target cells.

19
Q

What is the effect of TNF-α released locally by MACs in a tumour microenvironment?

A

It induces apoptosis in cancer cells.

20
Q

Which 3 metalloproteases are released by MACs to help phagocytize unusual, potentially cancerous cells?

A
  • MMP-7
  • MMP-9
  • MMP-12
21
Q

Why is the release of ROS by TAMs more dangerous than the release of ROS by MACs?

A

MACs release relatively low levels of ROS that are easily managed by antioxidant enzymes and vitamins; TAMs release much higher levels that are

22
Q

What is tissue factor?

A

A small protein that attracts wound-healing TAMs into a tumour microenvironment.

23
Q

What 2 classes of molecules recruit TAMs to a tumour microenvironment?

A
  • Tissue factor
  • Chemokines
24
Q

What is the role of metalloproteases released by TAMs in a tumour microenvironment?

A
25
Q

What types of pathways are stimulated by cytokines released by TAMs in a tumour microenvironment?

A

Mitogenic/growth factor pathways.

26
Q

What is the estimated number of antigens that T and B cells could theoretically recognize, given their diversification by DNA rearrangement?

A

1015.

27
Q

What are T-cell receptors (TCRs)?

A

Antibody-like molecules developed on the surface of cytoxic T (TC) cells that display an antigen-like recognition for a specific pathogen and allow the TC cell to recognize and bind target cells for removal.

28
Q

What happens to Langerhans cells once they have taken up antigens?

A

They migrate to the lymphatic system and enter the lymph node to mature into dendritic cells, where they expose their found antigens to T cells.

29
Q

What are MHC class II receptors?

A

Intracellular receptors in antigen-presenting cells that move oligopeptides from phagocytized foreign bodies to the cell surface.

30
Q
A